Network Working Group Jonathan P. Lang (Calient Networks)
Internet Draft Krishna Mitra (Calient Networks)
Expiration Date: September 2001 John Drake (Calient Networks)
Kireeti Kompella (Juniper Networks)
Yakov Rekhter (Juniper Networks)
Lou Berger (Movaz Networks)
Debanjan Saha (Tellium)
Debashis Basak (Accelight Networks)
Hal Sandick (Nortel Networks)
Alex Zinin (Cisco Systems)
Bala Rajagopalan (Tellium)
Link Management Protocol (LMP)
draft-ietf-mpls-lmp-02.txt
Status of this Memo
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all provisions of Section 10 of RFC2026 [RFC2026].
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Abstract
Future networks will consist of photonic switches, optical
crossconnects, and routers that may be configured with control
channels, links, and bundled links. This draft specifies a link
management protocol (LMP) that runs between neighboring nodes and is
used to manage traffic engineering (TE) links. Specifically, LMP
will be used to maintain control channel connectivity, verify the
physical connectivity of the data-bearing channels, correlate the
link property information, and manage link failures. A unique
feature of the fault management technique is that it is able to
localize failures in both opaque and transparent networks,
independent of the encoding scheme used for the data.
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Table of Contents
1. Introduction ................................................ 3
2. LMP Overview ................................................ 4
3. Control Channel Management .................................. 6
3.1 Parameter Negotiation ................................... 7
3.2 Hello Protocol .......................................... 8
3.2.1 Hello Parameter Negotiation ...................... 8
3.2.2 Fast Keep-alive .................................. 9
3.2.3 Control Channel Availability ..................... 10
3.2.4 Taking a Control Channel Down Administratively ... 10
3.2.5 Degraded (DEG) State ............................. 10
4. Link Property Correlation ................................... 11
5. Verfifying Link Connectivity ................................ 12
5.1 Example of Link Connectivity ............................ 14
6. Fault Management ............................................ 15
6.1 Fault Detection ......................................... 16
6.2 Fault Localization Mechanism ............................ 16
6.3 Channel Activation Indication............................ 16
6.4 Examples of Fault Localization .......................... 17
7. LMP Authentication .......................................... 18
8. LMP Finite State Machine .................................... 18
8.1 Control Channel FSM ..................................... 18
8.1.1 Control Channel States ........................... 19
8.1.2 Control Channel Events ........................... 19
8.1.3 Control Channel FSM Description .................. 22
8.2 TE Link FMS ............................................. 23
8.2.1 TE link States ................................... 23
8.2.2 TE link Events ................................... 24
8.2.3 TE link FSM Description .......................... 26
8.3 Data Link FSM ........................................ 27
8.3.1 Data Link States ................................. 27
8.3.2 Data Link Events ................................. 27
8.3.3 Active Data Link FSM Description ................. 29
8.3.4 Passive Data Link FSM Description ................ 30
9. LMP Message Formats ......................................... 30
9.1 Common Header ........................................... 30
9.2 LMP TLV Format .......................................... 33
9.3 Parameter Negotiation ................................... 36
9.4 Hello ................................................... 39
9.5 Link Verification ....................................... 40
9.6 Link Summary ............................................ 48
9.7 Fault Management ........................................ 53
10 Security Conderations........................................ 58
11. References ................................................. 58
12. Acknowledgments ............................................ 60
13. Authors' Addresses ........................................ 60
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Changes from previous version:
o Added LMP length field to the common header.
o Decoupled control channel and TE Link dependence. Removed
control channel switchover procedure.
o Modified the FSMs to align with current procedures.
o Modified ConfigAck & ConfigNack to echo the NodeId received in
the Config message.
o Modified the Test messages to include VerifyId (provided by
remote node) to differentiate test messages from different TE-
links or LMP peers when testing in parallel.
o Added Link Mux Capability to LinkSummary.
o Added flags to LinkSummary indicating status of the ports or
component links.
o Added Channel Activate messages to Fault Management procedure.
o General Text clarification including:
o difference between port and component link
o use of control channels
1. Introduction
Future networks will consist of photonic switches (PXCs), optical
crossconnects (OXCs), routers, switches, DWDM systems, and add-drop
multiplexors (ADMs) that use the Generalized MPLS (GMPLS) control
plane to dynamically provision resources and to provide network
survivability using protection and restoration techniques. A pair
of nodes (e.g., two PXCs) may be connected by thousands of fibers,
and each fiber may be used to transmit multiple wavelengths if DWDM
is used. Furthermore, multiple fibers and/or multiple wavelengths
may be combined into a single traffic-engineering (TE) link for
routing purposes. To enable communication between nodes for
routing, signaling, and link management, a control channel must be
established between the node pair. This draft specifies a link
management protocol (LMP) that runs between neighboring nodes and is
used to manage TE links.
In this draft, we will follow the naming convention of [LAMBDA] and
use OXC to refer to all categories of optical crossconnects,
irrespective of the internal switching fabric. We distinguish
between crossconnects that require opto-electronic conversion,
called digital crossconnects (DXCs), and those that are all-optical,
called photonic switches or photonic crossconnects (PXCs) - referred
to as pure crossconnects in [LAMBDA], because the transparent nature
of PXCs introduces new restrictions for monitoring and managing the
data links (see [PERF-MON] for proposed extensions to MPLS for
performance monitoring in photonic networks). LMP can be used for
any type of node, enhancing the functionality of traditional DXCs
and routers, while enabling PXCs and DWDMs to intelligently
interoperate in heterogeneous optical networks.
In GMPLS, the control channel between two adjacent nodes is no
longer required to use the same physical medium as the data-bearing
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links between those nodes. For example, a control channel could use
a separate wavelength or fiber, an Ethernet link, or an IP tunnel
through a separate management network. A consequence of allowing
the control channel(s) between two nodes to be physically diverse
from the associated data links is that the health of a control
channel does not necessarily correlate to the health of the data
links, and vice-versa. Therefore, a clean separation between the
fate of the control channel and data-bearing links must be made.
Furthermore, new mechanisms must be developed to manage the data-
bearing links, both in terms of link provisioning and fault
localization.
For the purposes of this document, a data-bearing link may be either
a "port" or a "component link" depending on its multiplexing
capability; component links are multiplex capable, whereas ports are
not multiplex capable. This distinction is important since the
management of such links (including, for example, resource
allocation, label assignment, and their physical verification) is
different based on their multiplexing capability. For example, a
SONET crossconnect with OC-192 interfaces may be able to demultiplex
the OC-192 stream into four OC-48 streams. If multiple interfaces
are grouped together into a single TE link using link bundling
[BUNDLE], then the link resources must be identified using three
levels: TE link Id, component interface Id, and timeslot label.
Resource allocation happens at the lowest level (timeslots), but
physical connectivity happens at the component link level. As
another example, consider the case where a PXC transparently
switches OC-192 lightpaths. If multiple interfaces are once again
grouped together into a single TE link, then link bundling [BUNDLE]
is not required and only two levels of identification are required:
TE link Id and port Id. Both resource allocation and physical
connectivity happen at the lowest level (i.e. port level). LMP is
designed to support aggregation of one or more data-bearing links
into a TE link (either ports into TE links, or component links into
TE links).
2. LMP Overview
LMP runs between a pair of nodes and includes a core set of
functions; two additional tools are defined in this draft to extend
the functionality of LMP and are optional. The core function set
includes control channel management and link property correlation.
Control channel management is used to establish and maintain control
channel connectivity between neighboring nodes. This is done using
lightweight Hello messages that act as a fast keep-alive mechanism
between the nodes. Link property correlation consists of a
LinkSummary message exchange that is used to synchronize the link
properties (e.g., local/remote Interface ID mappings) between the
adjacent nodes.
LMP requires that a pair of nodes have at least one active bi-
directional control channel between them. This control channel may
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be implemented using two uni-directional control channels that are
coupled together using the LMP Hello messages. All LMP messages are
IP encoded [except, in some cases, the Test Message which may be
limited by the transport mechanism for in-band messaging]; the link
level encoding of the control channel is outside the scope of this
document.
In LMP, multiple control channels may be active simultaneously
between a pair of nodes. Each control channel MUST individually
negotiate the control channel parameters, and each active control
channel MUST exchange LMP hello packets to maintain LMP
connectivity. If a group of control channels share a common node
pair and support the same LMP capabilities, then LMP control
messages MAY be transmitted over any of the active control channels
of that group without coordination between the local and remote
nodes. LMP also allows secondary (or backup) control channels to be
defined. For example, data-bearing may be used as backup control
channels provided control channel traffic has preemptive priority
over the data traffic on the link. Secondary control channels only
become active control channels when the switchover is complete and
they inherit the configuration properties of the primary control
channel that is being switched over to it.
The link property correlation function of LMP is designed to
aggregate multiple ports or component links into a TE link, and to
synchronize the properties of the TE link. As part of the link
property correlation function, a LinkSummary message exchange is
defined. The LinkSummary message includes the local and remote TE
Link Id, a list of all ports or component links that comprise the TE
link, and various link properties. In addition, TLVs may be
included further describing the TE link. A LinkSummaryAck or
LinkSummaryNack message MUST be sent in response to the receipt of a
LinkSummary message indicating agreement or disagreement of the link
properties.
In this draft, two additional tools are defined that extend the
functionality of LMP: link connectivity verification and fault
management. These tools are particularly useful when the control
channel is transmitted out-of-band from the data-bearing links.
Link connectivity verification is used to verify the physical
connectivity between the nodes and exchange the Interface Ids
(either Port Ids or Component Interface Ids, depending on the
configuration); these Ids are used in GMPLS signaling. The
procedure uses in-band Test messages that are sent over the data-
bearing links and TestStatus messages that are transmitted over the
control channel. The fault management scheme uses ChannelActive and
ChannelFail message exchanges between a pair of nodes to localize
failures in both opaque and transparent networks, independent of the
encoding scheme used for the data. As a result, both local span and
end-to-end path protection/restoration procedures can be initiated.
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For the LMP Test procedure, the free (unallocated) data-bearing
links MUST be opaque (i.e., able to be terminated); however, once a
data link is allocated, it may become transparent. The LMP Test
procedure is coordinated using a BeginVerify message exchange over
the control channel. To support various degrees of transparency
(e.g., examining overhead bytes, terminating the payload, etc.), and
hence, different mechanisms to transport the Test messages, a Verify
Transport Mechanism is included in the BeginVerify and
BeginVerifyAck messages. Note that there is no requirement that all
of the data-bearing links must be terminated simultaneously, but at
a minimum, they must be able to be terminated one at a time. There
is also no requirement that the control channel and TE link share
the same physical medium; however, the control channel MUST
terminate on the same two nodes that the TE link spans. Since the
BeginVerify message exchange coordinates the Test procedure, it also
naturally coordinates the transition of the data links between
opaque and transparent modes.
The LMP fault management procedure is based on two message
exchanges: ChannelActive and ChannelFail. The ChannelActive message
is used to indicate that one or more data-bearing channels are now
carrying user data. This is particularly useful for detecting
unidirectional channel failures in the transparent case. Receipt of
a ChannelActive message MUST be acknowledged with a ChannelActiveAck
message, the data-bearing channels MUST move to the ACTIVE state (if
not already there), and fault monitoring SHOULD be verified for the
corresponding data channels. The ChannelFail message is used to
indicate that one or more active data channels or an entire TE link
have failed. Receipt of a ChannelFail message MUST be acknowledged
with either a ChannelFailNack or ChannelFailAck message, depending
on if the channel failure is CLEAR or not in the adjacent node.
The organization of the remainder of this document is as follows.
In Section 3, we discuss the role of the control channel and the
messages used to establish and maintain link connectivity. In
Section 4, the link property correlation function using the
LinkSummary message is described. The link verification procedure
is discussed in Section 5. In Section 6, we show how LMP will be
used to isolate link and channel failures within the optical
network. Several finite state machines (FSMs) are given in Section
7 and the message formats are defined in Section 8.
3. Control channel management
To initiate an LMP session between two nodes, a bi-directional
control channel MUST be established. The control channel can be
used to exchange MPLS control-plane information such as link
provisioning and fault isolation information (implemented using a
messaging protocol such as LMP, proposed in this draft), path
management and label distribution information (implemented using a
signaling protocol such as RSVP-TE [RSVP-TE] or CR-LDP [CR-LDP]),
and network topology and state distribution information (implemented
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using traffic engineering extensions of protocols such as OSPF
[OSPF-TE] and IS-IS [ISIS-TE]). For the purposes of LMP, we do not
specify the exact implementation of the control channel; it could
be, for example, a separate wavelength or fiber, an Ethernet link,
an IP tunnel through a separate management network, or the overhead
bytes of a data-bearing link. Rather, we assign a node-wide unique
32-bit non-zero integer control channel identifier (CCId) to each
direction of the control channel. One possible way to assign a CCId
is to use the IP address or ifindex of the interface. Furthermore,
we define the control channel messages (which have control channel
identifiers in them) to be IP encoded. This allows the control
channel implementation to encompass both in-band and out-of-band
mechanisms; including the case where the control channel messages
are transmitted separately from the associated data link(s).
Furthermore, since the messages are sent directly over IP, the link
level encoding is not part of LMP.
The control channel can be either explicitly configured or
automatically selected, however, for the purpose of this document we
will assume the control channel is explicitly configured. Note that
for in-band signaling, a control channel could be allocated to a
data-bearing link; however, this is not true when the control
channel is transmitted separately from the data links.
Control channels exist independently of TE links and multiple
control channels may be active simultaneously between a pair of
nodes. The control channels may also be used for transmitting and
receiving signaling and routing messages. Each LMP control channel
MUST individually negotiate the control channel parameters, and each
active control channel MUST exchange LMP Hello packets to maintain
LMP connectivity. If a group of control channels share a common
node pair and support the same LMP capabilities, then LMP control
channel messages (except Config, ConfigAck, ConfigNack, and Hello)
may be transmitted over any of the active control channels without
coordination between the local and remote nodes.
For LMP, it is essential that at least one control channel is always
available. In the event of a control channel failure, it may be
possible to use an alternate active control channel without
coordination as mentioned above. Since control channels are
electrically terminated at each node, lower layers (e.g., SONET/SDH)
may also be used to detect control channel failures.
3.1. Parameter Negotiation
For LMP, a generic parameter negotiation exchange is defined using
Config, ConfigAck, and ConfigNack messages. The contents of these
messages are built using TLV triplets. Config TLVs can be either
negotiable or non-negotiable (identified by the N flag in the TLV
header). Negotiable TLVs can be used to let the devices agree on
certain values. Non-negotiable TLVs are used for announcement of
specific values that do not need, or do not allow, negotiation.
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To initiate the configuration procedure, a node MUST transmit Config
messages to the remote node. It is possible that both the local and
remote nodes initiate the configuration procedure at effectively the
same time. To avoid ambiguities, the node with the higher Node Id
wins the contention; the node with the lower Node Id SHOULD stop
transmitting the Config message and respond to the Config messages
it receives.
The Config message MUST be periodically transmitted until (1) it
receives a ConfigAck or ConfigNack message, (2) a timeout expires
and no ConfigAck or ConfigNack message has been received, or (3) it
receives a Config message from the remote node and has lost the
contention (e.g., the Node Id of the remote node is higher than the
Node Id of the local node). Both the retransmission interval and
the timeout period are local configuration parameters.
The Config message MUST include the LMP Capability TLV and the
HelloConfig TLV.
The ConfigAck message is used to acknowledge receipt of the Config
message and express agreement on ALL of the configured parameters
(both negotiable and non-negotiable). The ConfigNack message is
used to acknowledge receipt of the Config message, indicate which
(if any) non-negotiable parameters are unacceptable, and propose
alternate values for the negotiable parameters.
3.2. Hello protocol
Once a control channel is configured between two neighboring nodes,
a Hello protocol will be used to establish and maintain control
channel connectivity between the nodes and to detect control channel
failures. The Hello protocol of LMP is intended to be a lightweight
keep-alive mechanism that will react to control channel failures
rapidly so that IGP Hellos are not lost and the associated link-
state adjacencies are not removed unnecessarily. Furthermore, the
RSVP Hello of [RSVP-TE] is not needed since the LMP Hellos will
detect link layer failures.
The Hello protocol consists of two phases: a negotiation phase and a
keep-alive phase. Negotiation MUST only be done when the control
channel is in the CONFIG state, and is used to exchange the CCIds
and agree upon the parameters used in the keep-alive phase. The
keep-alive phase consists of a fast lightweight Hello message
exchange.
3.2.1. Hello Parameter Negotiation
Before sending Hello messages as part of the keep-alive phase, the
HelloInterval and HelloDeadInterval parameters MUST be agreed upon.
These parameters are exchanged as a HelloConfig TLV object in the
Config message. The HelloInterval indicates how frequently LMP
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Hello messages will be sent, and is measured in milliseconds (ms).
For example, if the value were 100, then the transmitting node would
send the Hello message at least every 100ms. The HelloDeadInterval
indicates how long a device should wait to receive a Hello message
before declaring a control channel dead, and is measured in
milliseconds (ms). The HelloDeadInterval MUST be greater than the
HelloInterval, and SHOULD be at least 3 times the value of
HelloInterval.
When a node has either sent or received a ConfigAck message, it may
begin sending Hello messages. Once it has both sent and received a
Hello message, the control channel moves to the UP state. If,
however, a node receives a ConfigNack message instead of a ConfigAck
message, the node MUST not send Hello messages.
In the event that multiple control channels are run over the same
physical control channel interface, the parameter negotiation phase
is run multiple times. The various LMP parameter negotiation
messages associated with their corresponding control channels are
tagged with their node-wide unique identifiers (CCIds).
3.2.2. Fast Keep-alive
Each Hello message contains two sequence numbers: the first sequence
number (TxSeqNum) is the sequence number for this Hello message and
the second sequence number (RcvSeqNum) is the sequence number of the
last Hello message received over this control channel from the
adjacent node. Each node increments its sequence number when it sees
its current sequence number reflected in Hellos received from its
peer. The sequence numbers start at 1 and wrap around back to 2; 0
is used in the RcvSeqNum to indicate that a Hello has not yet been
seen and 1 is used in the TxSeqNum to indicate a control channel
boot/reboot.
Under normal operation, the difference between the RcvSeqNum in a
Hello message that is received and the local TxSeqNum that is
generated will be at most 1. There are two cases where this
difference can be more than 1: when a control channel reboots and
when switching over to a backup control channel.
Having sequence numbers in the Hello messages allows each node to
verify that its peer is receiving its Hello messages. This provides
a two-fold service. First, the remote node will detect that a
control channel has rebooted if TxSeqNum=1. If this occurs, the
remote node will indicate its knowledge of the reboot by setting
RcvSeqNum=1 in the Hello messages that it sends and SHOULD wait to
receive a Hello message with TxSeqNum=2 before transmitting any
messages other than Hello messages. Second, by including the
RcvSeqNum in Hello packets, the local node will know which Hello
packets the remote node has received.
The following example illustrates how the sequence numbers operate:
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1) After completing the configuration stage, Node A sends a Hello
message with {TxSeqNum=1;RcvSeqNum=0}.
2) When Node A receives a Hello with {TxSeqNum=1;RcvSeqNum=1}, it
sends Hellos with {TxSeqNum=2;RcvSeqNum=1}.
3) After some time, the control channel on Node B reboots.
4) Node A is sending Hellos with {TxSeqNum=45;RcvSeqNum=44} and
receives a Hello from Node B with {TxSeqNum=1;RcvSeqNum=0},
indicating that Node B has rebooted. Node A sends Hello
messages with {TxSeqNum=45;RcvSeqNum=1}.
4) When Node A receives a Hello with {TxSeqNum=2;RcvSeqNum=45}, it
sends Hellos with {TxSeqNum=46;RcvSeqNum=2}.
3.2.3. Control Channel Availability
As mentioned above, LMP requires that a bi-directional control
channel is available, and LMP includes mechanisms to ensure that a
control channel is available. Control channels may need to be
switched as a result of the associated physical control channel
interface or link failure, or for administration purposes (e.g.,
routine fiber maintenance). During these times, peer connectivity
must be maintained to ensure that unnecessary rerouting of user
traffic is avoided and false failures are not reported.
If multiple active control channels share a common node pair and
support the same LMP capabilities, then any of the active control
channels may be used without coordination between the local and
remote nodes.
3.2.4. Taking a Control Channel Down Administratively
To ensure that bringing a control channel DOWN for administration
purposes is done gracefully, a ControlChannelDown flag is available
in the Common Header of LMP packets. When data links (ports or
component links) are still in use between a pair of nodes, a control
channel SHOULD only be taken down administratively when there are
other active control channels that can be used to manage the data
links.
When a node receives LMP packets with ControlChannelDown = 1, it
must first verify that it is able to bring the control channel down
on its end. Once the verification is done, it must set the
ControlChannelDown flag to 1 on all of the LMP packets that it
sends. When the node that initiated the ControlChannelDown
procedure receives LMP packets with ControlChannelDown = 1, it may
then stop sending Hello packets.
3.2.5. Degraded State
A consequence of allowing the control channels and data links to be
transmitted along a separate medium is that the TE link may be in a
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state where no active control channels are available, but the data
links (ports or component links) are still in use. For many
applications, it is unacceptable to tear down a link that is
carrying user traffic simply because the control channel is no
longer available; however, the traffic that is using the data links
may no longer be guaranteed the same level of service. Hence the TE
link is in a Degraded state.
When a TE link is in the Degraded state, routing and signaling
SHOULD be notified so that new connections are not accepted and
resources are no longer advertised for the TE link.
4. Link Property Correlation
As part of LMP, a link property correlation exchange is defined
using the LinkSummary, LinkSummaryAck, and LinkSummaryNack messages.
The contents of these messages are built using TLV triplets.
LinkSummary TLVs can be either negotiable or non-negotiable
(identified by the N flag in the TLV header). Negotiable TLVs can
be used to let both sides agree on certain link parameters. Non-
negotiable TLVs are used for announcment of specific values that do
not need, or do not allow, negotiation.
The LinkSummary message is used to aggregate multiple data links
(either ports or component links) into a TE link; exchange,
correlate, or change TE link parameters; and exchange, correlate, or
change Interface Ids (either Port Ids or Component Interface Ids).
The LinkSummary message can be exchanged at any time a link is UP
and not in the Verification process. The LinkSummary mesasge MUST
be periodically transmitted until (1) the node receives a
LinkSummaryAck or LinkSummaryNack message or (2) a timeout expires
and no LinkSummaryAck or LinkSummaryNack message has been received.
Both the retransmission interval and the timeout period are local
configuration parameters.
If the LinkSummary message is received from a remote node and the
Interface Id mappings match those that are stored locally, then the
two nodes have agreement on the Verification process (see Section
5). If the verification procedure is not used, the LinkSummary
message can be used to verify agreement on manual configuration.
Furthermore, any protection definitions that are included in the
LinkSummary message MUST be accepted or rejected by the local node.
The LinkSummaryAck message is used to signal agreement on the
Interface Id mappings and link property definitions. Otherwise, a
LinkSummaryNack message MUST be transmitted, indicating which
Interface mappings are not correct and/or which link properties are
not accepted. If a LinkSummaryNack message indicates that the
Interface Id mappings are not correct and the link verification
procedure is enabled, the link verification process SHOULD be
repeated for all mismatched free data links; if an allocated data
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link has a mapping mismatch, it SHOULD be flagged and verified when
it becomes free.
It is possible that the LinkSummary message could grow quite large
due to the number of Data Link TLVs. Since the LinkSummary message
is IP encoded, normal IP fragmentation should be used if the
resulting PDU exceeds the MTU.
5. Verifying Link Connectivity
In this section, we describe an optional mechanism that may be used
to verify the physical connectivity of the data-bearing links
(either ports or component links). The use of this procedure is
negotiated as part of the configuration exchange using the
Verification Procedure flag of the LMP Capability TLV. The
procedure SHOULD be done when establishing a TE link, and
subsequently, on a periodic basis for all unallocated (free) data
links of the TE link.
A unique characteristic of all-optical PXCs is that the data-bearing
links are not terminated at the PXC, but instead passes through
transparently. This characteristic of PXCs poses a challenge for
validating the connectivity of the data links since shining
unmodulated light through a link may not result in received light at
the next PXC. This is because there may be terminating (or opaque)
elements, such as DWDM equipment, in between the PXCs. Therefore,
to ensure proper verification of data link connectivity, we require
that until the links are allocated, they must be opaque. To support
various degrees of opaqueness (e.g., examining overhead bytes,
terminating the payload, etc.), and hence different mechanisms to
transport the Test messages, a Verify Transport Mechanism is
included in the BeginVerify and BeginVerifyAck messages. There is
no requirement that all data links be terminated simultaneously, but
at a minimum, the data links must be able to be terminated one at a
time. Furthermore, we assume that the nodal architecture is
designed so that messages can be sent and received over any data
link. Note that this requirement is trivial for DXCs (and OEO
devices in general) since each data link is received electronically
before being forwarded to the next DXC, but that in PXCs this is an
additional requirement.
To interconnect two nodes, a TE link is added between them, and at a
minimum, there MUST be at least one active control channel between
the nodes. A TE link MUST include at least one data link.
Once a control channel has been established between the two nodes,
data link connectivity can be verified by exchanging Ping-type Test
messages over each of the data links specified in the bundled link.
It should be noted that all LMP messages except for the Test message
are exchanged over the control channel and that Hello messages
continue to be exchanged over the control channel during the data
link verification process. The Test message is sent over the data
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link that is being verified. Data links are tested in the transmit
direction as they are uni-directional, and as such, it may be
possible for both nodes to exchange the Test messages
simultaneously.
To initiate the link verification process, the local node MUST send
a BeginVerify message over the control channel. The BeginVerify
message contains fields for the local and remote TE Link Ids. When
non-zero, these fields limit the scope of the data links being
verified to the corresponding TE link; if the fields are zero, the
data links can span multiple TE links and/or they may comprise a TE
link that is yet to be configured. The BeginVerify message contains
the number of data links that are to be verified; the interval
(called VerifyInterval) at which the Test messages will be sent; the
encoding scheme, the transport mechanisms that are supported, and
data rate for Test messages; when the data links correspond to
fibers, the wavelength over which the Test messages will be
transmitted is also included.
The BeginVerify message MUST be periodically transmitted until (1)
the node receives either a BeginVerifyAck or BeginVerifyNack message
to accept or reject the verify process or (2) a timeout expires and
no BeginVerifyAck or BeginVerifyNack message has been received.
Both the retransmission interval and the timeout period are local
configuration parameters.
If the remote node receives a BeginVerify message and it is ready to
process Test messages, it MUST send a BeginVerifyAck message back to
the local node specifying the desired transport mechanism for the
TEST messages. The remote node includes a 32-bit node unique
VerifyID in the BeginVerifyAck message. The VerifyID is then used
in all corresponding Test messages to differentiate them from
different LMP peers and/or parallel Test procedures. When the local
node receives a BeginVerifyAck message from the remote node, it may
begin testing the data links by transmitting periodic Test messages
over each data link. The Test message includes the Verify Id and
the local Interface Id for the associated data link. The remote
node MUST send either a TestStatusSuccess or a TestStatusFailure
message in response for each data link. A TestStatusAck message
MUST be sent to confirm receipt of the TestStatusSuccess and
TestStatusFailure messages.
The local (transmitting) node sends a given Test message
periodically (at least once every VerifyInterval ms) on the
corresponding data link until (1) it receives a correlating
TestStatusSuccess or TestStatusFailure message on the control
channel from the remote (receiving) node or (2) all active control
channels between the two nodes have failed. The remote node will
send a given TestStatus message periodically over the control
channel until it receives either a correlating TestStatusAck message
or an EndVerify message is received over the control channel.
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It is also permissible for the sender to terminate the Test
procedure without receiving a TestStatusSuccess or TestStatusFailure
message by sending an EndVerify message. Message correlation is
done using message identifiers and the Verify Id; this enables
verification of data links, belonging to different link bundles or
LMP sessions, in parallel.
When the Test message is detected at a node, the received Interface
Id (used in GMPLS as either a Port Id or Component Interface Id
depending on the configuration) is recorded and mapped to the local
Interface Id for that channel. The receipt of a TestStatusSuccess
message indicates that the Test message was detected at the remote
node and the physical connectivity of the data link has been
verified. The TestStatusSuccess message includes the local
Interface Id and the remote Interface Id (received in the Test
message), along with the VerifyId received in the Test message.
When the TestStatusSuccess message is received, the local node
SHOULD mark the data link as UP, send a TestStatusAck message to the
remote node, and begin testing the next data link. If, however, the
Test message is not detected at the remote node within an
observation period (specified by the VerifyDeadInterval), the remote
node will send a TestStatusFailure message over the control channel
indicating that the verification of the physical connectivity of the
data link has failed. When the local node receives a
TestStatusFailure message, it will mark the data link as FAILED,
send a TestStatusAck message to the remote node, and begin testing
the next data link. When all the data links on the list have been
tested, the local node SHOULD send an EndVerify message to indicate
that testing has been completed on this link. The EndVerify message
will be periodically transmitted until an EndVerifyAck message has
been received.
Both the local and remote nodes SHOULD maintain the complete list of
Interface Id mappings for correlation purposes.
5.1. Example of Link Connectivity
Figure 1 shows an example of the link verification scenario that is
executed when a link between PXC A and PXC B is added. In this
example, the TE link consists of three free ports (each transmitted
along a separate fiber) and is associated with a bi-directional
control channel (indicated by a "c"). The verification process is as
follows: PXC A sends a BeginVerify message over the control channel
ôcö to PXC B indicating it will begin verifying the ports. PXC B
receives the BeginVerify message and returns the BeginVerifyAck
message over the control channel to PXC A. When PXC A receives the
BeginVerifyAck message, it begins transmitting periodic Test
messages over the first port (Interface Id=1). When PXC B receives
the Test messages, it maps the received Interface Id to its own
local Interface Id = 10 and transmits a TestStatusSuccess message
over the control channel back to PXC A. The TestStatusSuccess
message will include both the local and received Interface Ids for
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the port. PXC A will send a TestStatusAck message over the control
channel back to PXC B indicating it received the TestStatusSuccess
message. The process is repeated until all of the ports are
verified. At this point, PXC A will send an EndVerify message over
the control channel to PXC B to indicate that testing is complete
and PXC B will respond by sending an EndVerifyAck message over the
control channel back to PXC A.
+---------------------+ +---------------------+
+ + + +
+ PXC A +<-------- c --------->+ PXC B +
+ + + +
+ + + +
+ 1 +--------------------->+ 10 +
+ + + +
+ + + +
+ 2 + /---->+ 11 +
+ + /----/ + +
+ + /---/ + +
+ 3 +----/ + 12 +
+ + + +
+ + + +
+ 4 +--------------------->+ 14 +
+ + + +
+---------------------+ +---------------------+
Figure 2: Example of link connectivity between PXC A and PXC B.
6. Fault Management
In this section, we describe an optional LMP mechanism that is used
to manage failures by rapidly locating link or channel failures.
The use of this procedure is negotiated as part of the configuration
exchange using the Fault Management Procedure flag of the LMP
Capability TLV. As before, we assume each link has a bi-directional
control channel that is always available for inter-node
communication and that the control channel spans a single hop
between two neighboring nodes. The case where a control channel is
no longer available between two nodes is beyond the scope of this
draft. The mechanism used to rapidly isolate link failures is
designed to work for unidirectional LSPs, and can be easily extended
to work for bi-directional LSPs; however, for the purposes of this
document, we only discuss the operation when the LSPs are
unidirectional.
Recall that a TE link connecting two nodes may consist of a number
of data links (ports or component links). If one or more data links
fail between two nodes, a mechanism must be used to rapidly locate
the failure so that appropriate protection/restoration mechanisms
can be initiated. An important implication of using PXCs is that
traditional methods that are used to monitor the health of allocated
data links in OEO nodes (e.g., DXCs) may no longer be appropriate,
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since PXCs are transparent to the bit-rate, format, and wavelength.
Instead, fault detection is delegated to the physical layer (i.e.,
loss of light or optical monitoring of the data) instead of layer 2
or layer 3.
6.1. Fault Detection
As mentioned earlier, fault detection must be handled at the layer
closest to the failure; for optical networks, this is the physical
(optical) layer. One measure of fault detection at the physical
layer is simply detecting loss of light (LOL). Other techniques for
monitoring optical signals are still being developed and will not be
further considered in this document. However, it should be clear
that the mechanism used to locate the failure is independent of the
mechanism used to detect the failure, but simply relies on the fact
that a failure is detected.
6.2. Fault Localization Mechanism
If data links fail between two PXCs, the power monitoring system in
all of the downstream nodes may detect LOL and indicate a failure.
To correlate multiple failures between a pair of nodes, a monitoring
window can be used in each node to determine if a single data link
has failed or if multiple data links (possibly an entire TE link)
have failed.
As part of the fault localization, a downstream node that detects
data link failures will send a ChannelFail message to its upstream
neighbor (bundling together the notification of all of the failed
data links). An upstream node that receives the ChannelFail message
will correlate the failure to see if there is a failure on the
corresponding LSP(s). If the failure has also been detected on the
input port(s) of the upstream node, the node will return a
ChannelFailAck message to the downstream node (bundling together the
notification of all the data links), indicating that it too has
detected a failure. If, however, the fault is CLEAR in the upstream
node (e.g., there is no LOL on the corresponding input channels),
then the upstream node will have localized the failure and will
return a ChannelFailNack message to the downstream node. Once the
failure has been localized, the signaling protocols can be used to
initiate span or path protection/restoration procedures.
If all of the data links of a TE link have failed, then the upstream
node MAY be notified of the TE link failure without specifying that
each data link of the TE link has failed. To do this, the Interface
Id of the ChannelFail subobject MUST be 0.
6.3. Channel Activiation Indication
The ChannelActive message is the counterpart to the ChannelFail
message described in Section 6.2 and is used to notify the
downstream neighboring node that the data link is in the Active
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state. This is particularly useful in networks with transparent
nodes where the status of data links may need to be triggered using
control channel messages. For example, if a data link is pre-
provisioned and the physical link fails after verification and
before inserting user traffic, the pair of nodes need a mechanism to
indicate the data link is active or they may not be able to detect
the failure.
The ChannelActive message is used to indicate that a channel or
group of channels are now active. The ChannelActiveAck message MUST
be transmitted upon receipt of a ChannelActive message. When a
ChannelActive message is received, the corresponding data link(s)
MUST be put into the Active state. If upon putting them into the
Active state, a failure is detected, the ChannelFail message MUST be
transmitted as described in Section 6.2.
6.4. Examples of Fault Localization
In Fig. 2, a sample network is shown where four PXCs are connected
in a linear array configuration. The control channels are bi-
directional and are labeled with a "c". All LSPs are uni-
directional going left to right.
In the first example [see Fig. 2(A)], there is a failure on a single
data link between PXC2 and PXC3. Both PXC3 and PXC4 will detect the
failure and each node will send a ChannelFail message to the
corresponding upstream node (PXC3 will send a message to PXC2 and
PXC4 will send a message to PXC3). When PXC3 receives the
ChannelFail message from PXC4, it will correlate the failure and
return a ChannelFailAck message back to PXC4. Upon receipt of the
ChannelFailAck message, PXC4 will move the associated ports into a
standby state. When PXC2 receives the ChannelFail message from PXC3,
it will correlate the failure, verify that it is CLEAR, localize the
failure to the data link between PXC2 and PXC3, and send a
ChannelFailNack message back to PXC3.
In the second example [see Fig. 2(B)], there is a failure on three
data links between PXC3 and PXC4. In this example, PXC4 has
correlated the failures and will send a bundled ChannelFail message
for the three failures to PXC3. PXC3 will correlate the failures,
localize them to the channels between PXC3 and PXC4, and return a
bundled ChannelFailNack message back to PXC4.
In the last example [see Fig. 2(C)], there is a failure on the
tributary link of the ingress node (PXC1) to the network. Each
downstream node will detect the failure on the corresponding input
ports and send a ChannelFail message to the upstream neighboring
node. When PXC2 receives the message from PXC3, it will correlate
the ChannelFail message and return a ChannelFailAck message to PXC3
(PXC3 and PXC4 will also act accordingly). Since PXC1 is the ingress
node to the optical network, it will correlate the failure and
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localize the failure to the data link between itself and the network
element outside the optical network.
+-------+ +-------+ +-------+ +-------+
+ PXC 1 + + PXC 2 + + PXC 3 + + PXC 4 +
+ +-- c ---+ +-- c ---+ +-- c ---+ +
----+---\ + + + + + + +
+ \--+--------+-------+---\ + + + /--+--->
----+---\ + + + \---+-------+---##---+---/ +
+ \--+--------+-------+--------+-------+---##---+-------+--->
----+-------+--------+-------+--------+-------+---##---+-------+--->
----+-------+--------+---\ + + + (B) + +
+ + + \--+---##---+--\ + + +
+ + + + (A) + \ + + +
-##-+--\ + + + + \--+--------+-------+--->
(C) + \ + + /--+--------+---\ + + +
+ \--+--------+---/ + + \--+--------+-------+--->
+ + + + + + + +
+-------+ +-------+ +-------+ +-------+
Figure 3: We show three types of data link failures (indicated
by ## in the figure): (A) a single data link fails
between two PXCs, (B) three data links fail between
two PXCs, and (C) a single data link fails on the
tributary input of PXC 1. The control channel
connecting two PXCs is indicated with a "c".
7. LMP Authentication
LMP authentication is optional (included in the Common Header) and,
if used, MUST be supported by both sides of the control channel. The
method used to authenticate LMP packets is based on the
authentication technique used in [OSPF]. This uses cryptographic
authentication using MD5.
As a part of the LMP authentication mechanism, a flag is included in
the LMP common header indicating the presence of authentication
information. Authentication information itself is appended to the
LMP packet. It is not considered to be a part of the LMP packet, but
is transferred in the same IP packet.
When the Authentication flag is set in the LMP packet header, an
authentication data block is attached to the packet. This block has
a standard authentication header and a data portion. The contents of
the data portion depend on the authentication type. Currently, only
MD5 is supported for LMP.
8. LMP Finite State Machines
8.1. Control Channel FSM
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The control channel FSM defines the states and logics of operation
of an LMP control channel. The description of FSM state transitions
and associated actions is given in Section 3.
8.1.1. Control Channel States
A control channel can be in one of the states described below.
Every state corresponds to a certain condition of the control
channel and is usually associated with a specific type of LMP
message that is periodically transmitted to the far end.
Down: This is the initial control channel state. In this
state, no attempt is being made to bring the control
channel up and no LMP messages are sent. The control
channel parameters should be set to the initial values.
ConfigSnd: The control channel is in the parameter negotiation
state. In this state the node periodically sends a
Config message, and is expecting the other side to
reply with either a ConfigAck or ConfigNack message.
The FSM does not transition into the Active state until
the remote side positively acknowledges the parameters.
ConfRcv: The control channel is in the parameter negotiation
state. In this state, the node is waiting for
acceptable configuration parameters from the remote
side. Once such parameters are received and
acknowledged, the FSM can transition to the Active
state.
Active: In this state the node periodically sends a Hello
message and is waiting to receive a valid Hello
message. Once a valid Hello message is received, it
can transition to the UP state.
Up: The CC is in an operational state. The node receives
valid Hello messages and sends Hello messages.
GoingDown: A CC may go into this state because of two reasons:
administrative action, and a ControlChannelDown bit
received in an LMP message. While a CC is in this
state, the node sets the ControlChannelDown bit in all
the messages it sends.
8.1.2. Control Channel Events
Operation of the LMP control channel is described in terms of FSM
states and events. Control channel Events are generated by the
underlying protocols and software modules, as well as by the packet
processing routines and FSMs of associated TE links. Every event
has its number and a symbolic name. Description of possible control
channel events is given below.
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1 : evBringUp: This is an externally triggered event indicating
that the control channel negotiation should begin.
This event, for example, may be triggered by a
provisioner command or by the successful
completion of a control channel bootstrap
procedure. Depending on the configuration, this
will trigger either
1a) the sending of a Config message,
1b) a period of waiting to receive a Config
message from the remote node.
2 : evCCDn: This event is generated when there is indication
that the control channel is no longer available.
3 : evConfDone: This event indicates a ConfigAck message has been
received, acknowledging the Config parameters.
4 : evConfErr: This event indicates a ConfigNack message has been
received, rejecting the Config parameters.
5 : evNewConfOK: New Config message was received from neighbor and
positively Acknowledged.
6 : evNewConfErr: New Config message was received from neighbor and
rejected with a ConfigNack message.
7 : evContenWin: New Config message was received from neighbor at
the same time a Config message was sent to the
neighbor. The Local node wins the contention. As
a result, the received Config message is ignored.
8 : evContenLost: New Config message was received from neighbor at
the same time a Config message was sent to the
neighbor. The Local node looses the contention.
As a result, the node must (positively or
negatively) respond to the Config message.
9 : evAdminDown: The administrator has requested that the control
channel is brought down administratively.
10: evDownOk: A packet with the LinkDown flag has been received
and the local node was the initiator of the link
down procedure.
11: evDownErr: A timer has expired indicating that the other node
did not start setting the LinkDown flag in its
messages.
12: evNbrGoesDn: A packet with LinkDown flag is received from the
neighbor.
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13: evHelloRcvd: A Hello packet with expected SeqNum has been
received.
14: evHoldTimer: The HelloDeadInterval timer has expired indicating
that no Hello packet has been received. This
moves the control channel back into the
Negotiation state, and depending on the local
configuration, this will trigger either
14a) the sending of periodic Config messages,
14b) a period of waiting to receive Config
messages from the remote node.
15: evSeqNumErr: A Hello with unexpected SeqNum received and
discarded.
16: evReconfig: Control channel parameters have been reconfigured
and require renegotiation.
17: evConfRet: A retransmission timer has expired and a Config
message is resent.
18: evHelloRet: The HelloInterval timer has expired and a Hello
packet is sent.
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8.1.3 Control Channel FSM Description
Figure 4 illustrates operation of the control channel FSM
in a form of FSM state transition diagram.
+--------+
+----------->| |<--------------+
| | Down |<----------+ |
| +--------| |<-------+ | |
| | +--------+ | | |
| | | ^ 2| 2| 2|
| |1b 1a| | | | |
| | v | 2 | | |
| | +--------+ | | |
| | +->| |<------+| | |
| | 4,7,| |ConfSnd | || | |
| | 17 +--| |<----+ || | |
| | +--------+ | || | |
| | 3| | | || | |
| | +--------+ |8 4,14a| || | |
| | | v | || | |
| +-|----->+--------+ | || | |
| | +->| |-----|-|+ | |
| | 6| |ConfRcv | | | | |
| | +--| |<--+ | | | |
| | +--------+ | | | | |
| | 5| ^ | | | | |
| +--------+ | | | | | | |
| | | | | | | | |
|10,2 v v |6,14b | | | | |
+--------+ +--------+ | | | | |
| | +--| |---|-+ | | |
| GoingDn| 5,18| | Active |-------|---+ |
| | +->| | | | |
+--------+ +--------+ | | |
^ 13| ^ | | |
| | |5 | | |
| v | 6,14b| | |
|9,12 +--------+ | |14a,16 |
+------------| |---+ | |
| Up |-------+ |
| |---------------+
+--------+
| ^
| |
+---+
13,15,18
Figure 4: Control Channel FSM
Event evCCDn always forces the FSM to the Down State. Events
evHoldTimer evReconfig always force the FSM to the Negotiation state
(either ConfigSnd or ConfigRcv).
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8.2 TE Link FSM
The TE Link FSM defines the states and logics of operation of an LMP
TE Link.
8.2.1 TE Link States
An LMP TE link can be in one of the states described below. Every
state corresponds to a certain condition of the TE link and is
usually associated with a specific type of LMP message that is
periodically transmitted to the far end via the associated control
channel or in-band via the data links.
Down: There are no control channels available and no data
links are allocated to the TE link.
LinkVrf: In this state, the link verification procedure is
performed for the data links of the TE link. LinkVrf is
a composite state that consists of two substates
described below.
VrfBegin: This state is valid only for the side initiating the
verification process. In this state, the node
periodically sends a BeginVerify message and expects an
BeginVerifyAck or BeginVerifyNack message. The
BeginVerify messages include information about the data
links in the BegVerify state.
VrfProcess: In this state, two FSMs are performing the link
verification procedure. The initiator periodically sends
Test messages over the data links in the Testing state
and waits for TestStatus messages to be received over a
control channel. The passive side listens for incoming
link test messages on the data links in the PasvTst
state.
VrfResult: In this state, the passive side periodically retransmits
the TestStatus messages for the data links verified
during the link verification procedure and waits for
acknowledgement. Once all messages have been
acknowledged, the passive side can go out of VrfResult
state. The initiator waits for the incoming TestStatus
message and goes out of it after receiving and
acknowledging TestStatus messages for all data links.
Note that the initiator must be prepared to receive and
acknowledge the TestStatus messages even after it has
transitioned out of the VrfResult state.
Summary: In this state, the new TE link configuration is
announced by periodically sending the LinkSummary
messages over the control channel.
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Up: This is the normal operational state of the TE link. At
least one primary CC is required to be operational
between the nodes sharing the TE link.
Degraded: In this state, all primary CCs are down, but the TE link
still includes some allocated data links.
STDBY: A ChannelFail message has been received indicating a
failure has been detected on the far-end node of the TE
link. The failure is locally correlated to determine if
the failure can be localized to the TE link or if the
failure is further upstream along the path.
8.2.2 TE Link Events
Operation of the LMP TE link is described in terms of FSM states and
events. TE Link events are generated by the packet processing
routines and by the FSMs of the associated primary control
channel(s) and the data links. Every event has its number and a
symbolic name. Description of possible control channel events is
given below.
1 : evCCUp: First primary CC goes Up
2 : evCCDown: Last primary CC goes Down
3 : evVerDone: Verification done; EndVerifyAck message
received.
4 : evVerify: An external event indicates that the Link
verification procedure should begin.
5 : evRecnfReq: TE link has been reconfigured and the new
configuration needs to be announced/agreed upon.
6 : evSummaryAck: LinkSummaryAck message has been received
acknowledging the TE link configuration.
7 : evLastCompDn: The last allocated data link has been freed.
8 : evStartVer: BeginVerifyAck message has been received
indicating the remote node is ready to start
link verification.
9 : evTELinkOk: An external event has indicated that the TE link
is available.
10: evBeginRet: Retransmission timer expires and no
BeginVerifyAck or BeginVerifyNack message has
been received. BeginVerify message is resent.
11: evSummaryRet: Retransmission timer expires and no
LinkSummaryAck or LinkSummaryNack message has
been received. LinkSummary message is resent.
12: evChannFail: ChannelFail message is received for TE link.
The failure is locally correlated and either a
ChannelFailAck or a ChannelFailNack message is
transmitted.
13: evNodeReBoot: The neighboring node has rebooted.
14: evSummaryNack1: LinkSummaryNack message has been received
indicating negotiable parameters not accepted.
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15: evSummaryNack2 LinkSummaryNack message received indicating
misconfiguration of non-negotiable parameters.
Free ports that are misconfigured are moved to
Down state. Allocated ports that are
misconfigured are flagged.
16: evSummaryNack3: LinkSummaryNack message has been received
indicating misconfiguration of non-negotiable
parameters for all ports.
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8.2.3 TE Link FSM Description
Figure 5 illustrates operation of the LMP TE Link FSM in a form of
FSM state transition diagram.
+--------+
+------------>| |
| +----->| Down |
| | +----| |
| | | +--------+
| | | |
| | | 4|
| | |9 |
| | | v
| | | +--------+
| | | 2 | |<-+
| +---|-|----| VrfBeg | |10
| | | | | |--+
| | | | +--------+
| | | | 8| ^
| | | | | |
| | | | | +---------+
| | | | v |
| | | | +-------+ |
| | | | 2 | | |
| +---|-|----|VrfProc| |
| | | | | | |
| | | | +-------+ |
| | | | 3| |
| | | | | +----------+
| | | | v |4 |
| | | | 16 +-------+ |
| | +-|----| |<-+ |
| | +--->|Summary| |11,14 |
| | +--------| |--+ |
| | |2 +-------+ |
| | | 6,15| ^ |
| | | | | |
| | | | | |
|7 | | | | |
| v v v |5,13 |
+--------+ +--------+ |
| |1 | |--------+
| Deg |------>| Up | 4
| |<------| |
+--------+ 2+--------+
| ^
| |
+--+
12
Figure 5: LMP TE Link FSM
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8.3 Data Link FSM
The data link FSM defines the states and logics of operation of a
port or component link within an LMP TE link. Operation of a data
link is described in terms of FSM states and events. Data-bearing
links can either be in the active (transmitting) state, where Test
messages are transmitted from them, or the passive (receiving)
state, where Test messages are received through them. For clarity,
we define separate FSMs for the active/passive data-bearing links;
however, we define a single set of data link states and events.
8.3.1 Data Link States
Any data link can be in one of the states described below. Every
state corresponds to a certain condition of the TE link.
Down: The data link has not been put in the resource pool.
Test: The data link is being tested. An LMP Test message
is periodically sent through the link.
PasvTest: The data link is being checked for incoming test
messages.
Retest: The data link is being re-validated. An LMP Test
message is periodically sent through the link.
PasvRetest: The data link is being checked for incoming
test.messages as part of link re-validation.
Up/Free: The link has been successfully tested and is now put
in the pool of resources. The link has not yet been
allocated to data traffic.
Up/Allocated: The link has been allocated for data traffic.
Degraded: The link was in the Up/Allocated state when the last
CC associated with data link's TE Link has gone down.
The link is put in the Degraded state, since it is
still being used for data LSP.
TstRecv: A Test message has been detected on the data link and
a TestStatusSuccess message has been sent to the
transmitter over the control channel.
8.3.2 Data Link Events
Data bearing link events are generated by the packet processing
routines and by the FSMs of the associated control channel and the
Lang et al [Page 27]
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TE link. Every event has its number and a symbolic name.
Description of possible data link events is given below:
1 :evCCUp: CC has gone up.
2 :evCCDown: LMP neighbor connectivity is lost. This indicates
the last LMP control channel has failed between
neighboring nodes.
3 :evStartTst: This is an external event that triggers the sending
of Test messages over the data bearing link.
4 :evStartPsv: This is an external event that triggers the
listening for Test messages over the data bearing
link.
5 :evTestOK: Link verification was successful and the link can
be used for path establishment.
(a) This event indicates the Link Verification
procedure (see Section 5) was successful
for this data link and a TestStatusSuccess
message was received over the control
channel.
(b) This event indicates the link is ready for
path establishment, but the Link
Verification procedure was not used. For
in-band signaling of the control channel,
the control channel establishment may be
sufficient to verify the link.
6 :evTestRcv: Test message was received over the data port and a
TestStatusSuccess message is transmitted over the
control channel.
7 :evTestFail: Link verification returned negative results. This
could be because (a) a ChannelStatusFailure message
was received, or (b) an EndVerifyAck message was
received without receiving a ChannelStatusSuccess
or ChannelStatusFailure message for the data link.
8 :evPsvTestFail:Link verification returned negative results. This
indicates that a Test message was not detected and
either (a) the VerifyDeadInterval has expired or
(b) an EndVerifyAck messages has been received and
the VerifyDeadInterval has not yet expired.
9 :evLnkAlloc: The data link has been allocated.
10:evLnkDealloc: The data link has been deallocated.
11:evTestRet: A retransmission timer has expired and the Test
message is resent.
11:evVerifyAbrt: The other side did not confirm it is ready to
perform link verification.
12:evSummaryFail:The LinkSummary did not match for this data port.
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7.3.3 Active Data Link FSM Description
Figure 6 illustrates operation of the LMP active data link FSM in a
form of FSM state transition diagram.
+------+
+------------->| |
| +--------->| Down |<---------+
| | +----| | |
| | | +------+ |
| | |5b 3| ^ |
| | | | |2,7 |
| | | v | |
| | | +------+ |
| | | | |<-+ |
| | | | Test | |11 |
| | | | |--+ |
| | | +------+ |
| | | 5a| |
| | | | |2,7
| | | v |
| |2,12 | +---------+ 3 +--------+
| | +-->| |---->| |
| | | Up/Free | | Retest |
| +---------| |<----| |
| +---------+ 5a +--------+
| 9| ^
| | |
|10 v |10
+-----+ 2 +---------+
| |<--------| |
| Deg | |Up/Alloc |
| |-------->| |
+-----+ 1 +---------+
Figure 6: Active LMP Data Link FSM
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8.3.3 Passive Data Link FSM Description
Figure 7 illustrates operation of the LMP passive data link FSM in a
form of FSM state transition diagram.
+------+
+----------->| |
| +-------->| Down |<-----------+
| | +-----| | |
| | | +------+ |
| | |5b 4| ^ |
| | | | |2 |
| | | v | |
| | | +----------+ |
| | | | PasvTest | |
| | | +----------+ |
| | | 6| |
| | | | |2
| | | v |
| |2,12 | +---------+ 4 +------------+
| | +--->| Up/Free |---->| |
| | | | | PasvRetest |
| +----------| |<----| |
| +---------+ 5b +------------+
| 9| ^
| | |
|10 v |10
+-----+ +---------+
| | 2 | |
| Deg |<--------|Up/Alloc |
| |-------->| |
+-----+ 1 +---------+
Figure 7: Passive LMP Data Link FSM
9. LMP Message Formats
All LMP messages are IP encoded (except, in some cases, the Test
message are limited by the transport mechanism for in-band
messaging) with protocol Id = 140 (value not yet assigned by IANA).
9.1. Common Header
In addition to the standard IP header, all LMP messages (except, in
some cases, the Test messages are limited by the transport mechanism
for in-band messaging) have the following common header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vers | (Reserved) | Flags | Msg Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| LMP Length | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Control Channel Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Vers: 4 bits
Protocol version number. This is version 1.
Flags: 8 bits. The following values are defined. All other values
are reserved.
0x01: ControlChannelDown
0x02: Node Reboot
This bit is set to indicate the node has rebooted. This
flag may be reset to 0 when a Hello message is received
with RcvSeqNum equal to the local TxSeqNum.
0x04: DWDM Node
If this bit is set, the node is identifying itself as a
DWDM system. This is used when running LMP-DWDM
extensions as defined in [LMP-DWDM].
0x08: Authenticatino
When set, this bit indicates that an authentication
block is attached at the end of the LMP message. See
Sections 7 and 8.3 for more details.
Msg Type: 8 bits. The following values are defined. All other
values are reserved.
1 = Config
2 = ConfigAck
3 = ConfigNack
4 = Hello
5 = BeginVerify
6 = BeginVerifyAck
7 = BeginVerifyNack
8 = EndVerify
9 = EndVerifyAck
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10 = Test
11 = TestStatusSuccess
12 = TestStatusFailure
13 = TestStatusAck
14 = LinkSummary
15 = LinkSummaryAck
16 = LinkSummaryNack
17 = ChannelFail
18 = ChannelFailAck
19 = ChannelFailNack
20 = ChannelActive
21 = ChannelActiveAck
All of the messages are sent over the control channel EXCEPT
the Test message which is sent over the data link that is being
tested.
LMP Length: 16 bits
The total length of this LMP message in bytes, including the
common header and any variable-length objects that follow.
Checksum: 16 bits
The standard IP checksum of the entire contents of the LMP
message, starting with the LMP message header. This checksum is
calculated as the 16-bit one's complement of the one's
complement sum of all the 16-bit words in the packet. If the
packet's length is not an integral number of 16-bit words, the
packet is padded with a byte of zero before calculating the
checksum.
Local Control Channel Id: 32 bits
The Local Control Channel Id (CCId) identifies the control
channel of the sender associated with the message and is node-
wide unique. This value MAY be ignored upon receipt of the
Test message.
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9.2 LMP TLV Format
Many LMP messages are TLV based. The format the LMP TLV is as
follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (TLV Object) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
N: 1 bit
The N flag indicates if the object is a negotiable parameter
(N=1) or a non-negotiable parameter (N=0).
Type: 15 bits
The Type field indicates the TLV type.
Length: 16 bits
The Length field indicates the length of the TLV object in
bytes.
9.3 Authentication
When authentication is used for LMP, the authentication itself is
appended to the LMP packet. It is not considered to be a part of
the LMP packet, but is transmitted in the same IP packet as shown
below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// LMP Common Header //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// LMP Payload //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Authentication Block //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The authentication block looks as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Auth Type | Key ID | Auth Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cryptographic Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| MD5 Signature (16) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Auth Type: 8 bits
This defines the type of authentication used for LMP
messages. The following authentication types are
defined, all other are reserved for future use:
0 No authentication
1 Cryptographic authentication
Key ID: 8 bits
This field is defined only for cryptographic
authentication.
Auth Data Length: 8 bits
This field contains the length of the data portion of the
authentication block.
LMP authentication is performed on a per control channel basis. The
packet authentication procedure is very similar to the one used in
OSPF, including multiple key support, key management, etc. The
details specific to LMP are defined below.
Sending authenticated packets
-----------------------------
When a packet needs to be sent over a control channel and an
authentication method is configured for it, the Authentication flag
in the LMP header is set to 1, the LMP Length field is set to the
length of the LMP packet only, not including the authentication
block.
1) The Checksum field in the LMP packet is set to zero (this will
make the receiving side drop the packet if authentication is not
supported).
2) The LMP authentication header is filled out properly. The message
digest is calculated over the LMP packet together with the LMP
authentication header. The input to the message digest
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calculation consists of the LMP packet, the LMP authentication
header, and the secret key. When using MD5 as the authentication
algorithm, the message digest calculation proceeds as follows:
(a) The authentication header is appended to the LMP packet.
(b) The 16 byte MD5 key is appended after the LMP authentication
header.
(c) Trailing pad and length fields are added, as specified in
[MD5].
(d) The MD5 authentication algorithm is run over the
concatenation of the LMP packet, authentication header,
secret key, pad and length fields, producing a 16 byte
message digest (see [MD5]).
(e) The MD5 digest is written over the secret key (i.e., appended
to the original authentication header).
The authentication block is added to the IP packet right after the
LMP packet, so IP packet length includes the length of both LMP
packet and LMP authentication blocks.
Receiving authenticated packets
-------------------------------
When an LMP packet with the Authentication flag set has been received
on a control channel that is configured for authentication, it must
be authenticated. The value of the Authentication field MUST match
the authentication type configured for the control channel (if any).
If an LMP protocol packet is accepted as authentic, processing of the
packet continues. Packets that fail authentication are discarded.
Note that the checksum field in the LMP packet header is not checked
when the packet is authenticated.
(1) Locate the receiving control channel's configured key having Key
ID equal to that specified in the received LMP authentication
block. If the key is not found, or if the key is not valid for
reception (i.e., current time does not fall into the key's
active time frame), the LMP packet is discarded.
(2) If the cryptographic sequence number found in the LMP
authentication header is less than the cryptographic sequence
number recorded in the control channel data structure, the LMP
packet is discarded.
(3) Verify the message digest in the data portion of the
authentication block in the following steps:
(a) The received digest is set aside.
(b) A new digest is calculated, as specified in the previous
section.
(c) The calculated and received digests are compared. If they
do not match, the LMP packet is discarded. If they do
match, the LMP protocol packet is accepted as authentic, and
the "cryptographic sequence number" in the control channel's
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data structure is set to the sequence number found in the
packet's LMP header.
9.4 Parameter Negotiation
9.4.1 Config Message (MsgType = 1)
The Config message is used in the negotiation phase of LMP. The
contents of the Config message are built using TLV triplets. TLVs
can be either negotiable or non-negotiable (identified by the N flag
in the TLV header). Negotiable TLVs can be used to let the devices
agree on certain values. Non-negotiable TLVs are used for
announcement of specific values that do not need or do not allow
negotiation. The format of the Config message is as follows:
<Config Message> ::= <Common Header> <Config>
The Config Object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Config TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Node ID: 32 bits.
This is the Node ID for the node.
MessageId: 32 bits.
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgment.
9.4.1.1 HelloConfig TLV
The HelloConfig TLV is TLV Type=1 and is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N| 1 | 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HelloInterval | HelloDeadInterval |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Length field of HelloConfig is always set to 4.
N: 1 bit
The N flag indicates if the parameter is negotiable (N=1) or
non-negotiable (N=0).
HelloInterval: 16 bits.
Indicates how frequently the Hello packets will be sent and is
measured in milliseconds (ms).
HelloDeadInterval: 16 bits.
If no Hello packets are received within the HelloDeadInterval,
the control channel is assumed to have failed and is measured
in milliseconds (ms).
9.4.1.2 LMP Capability TLV
The LMP Capability TLV is TLV Type=2 and is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N| 2 | 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Capability Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Length field of LMP Capability TLV is always set to 4.
N: 1 bit
The N flag indicates if the parameter is negotiable (N=1) or
non-negotiable (N=0).
Capability Flags: 32 bits
The Capability Flags indicate which extended LMP procedures
will be supported. A value of 0 indicates that only the base
LMP procedures are supported. More than one bit may be set to
indicate multiple extended LMP procedures are supported.
The following flags are defined:
0x01 Link Verification Procedure
0x02 Fault Management Procedure
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0x04 LMP-DWDM Procedure. See [LMP-DWDM].
9.4.2 ConfigAck Message (MsgType = 2)
The ConfigAck message is used to indicate the receipt of the Config
message and indicate agreement on all parameters.
<ConfigAck Message> ::= <Common Header> <ConfigAck>
The ConfigAck Object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Node ID: 32 bits.
This is the Node ID for the node sending the ConfigAck message.
MessageId: 32 bits.
This is copied from the Config message being acknowledged.
Rcv Node ID: 32 bits.
This is copied from the Config message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the Config message being acknowledged.
9.4.3 ConfigNack Message (MsgType = 3)
The ConfigNack message is used to indicate disagreement on non-
negotiable parameters or propose other values for negotiable
parameters. Parameters where agreement was reached MUST NOT be
included in the ConfigNack Object. The format of the ConfigNack
message is as follows:
<ConfigNack Message> ::= <Common Header> <ConfigNack>
The ConfigNack Object has the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Config TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Node ID: 32 bits.
This is the Node ID for the node.
MessageId: 32 bits.
This is copied from the Config message being negatively
acknowledged.
Rcv Node ID: 32 bits.
This is copied from the Config message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the Config message being negatively acknowledged.
The Config TLVs MUST include acceptable values for all negotiable
parameters. If the ConfigNack includes Config TLVs for non-
negotiable parameters, they MUST be copied from the Config TLVs
received in the Config message.
9.5 Hello Message (MsgType = 4)
The format of the Hello message is as follows:
<Hello Message> ::= <Common Header> <Hello>.
The Hello object format is shown below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TxSeqNum |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RcvSeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TxSeqNum: 32 bits
This is the current sequence number for this Hello message.
This sequence number will be incremented when either (a) the
sequence number is reflected in the RcvSeqNum of a Hello packet
that is received over the control channel, or (b) the Hello
packet is transmitted over a backup control channel.
TxSeqNum=0 is not allowed.
TxSeqNum=1 is reserved to indicate that a node has booted or
rebooted.
RcvSeqNum: 32 bits
This is the sequence number of the last Hello message received
over the control channel. RcvSeqNum=0 is reserved to indicate
that a Hello message has not yet been received.
9.6 Link Verification
9.6.1 BeginVerify Message (MsgType = 5)
The BeginVerify message is sent over the control channel and is used
to initiate the link verification process. The format is as
follows:
<BeginVerify Message> ::= <Common Header> <BeginVerify>
The BeginVerify object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | VerifyInterval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Data Links |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EncType | Verify Transport Mechanism |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitRate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Wavelength |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flags: 16 bits
The following flags are defined:
0x01 TE Link type
If this bit is set, the TE Link Id is numbered;
otherwise the TE Link Id is unnumbered.
0x02 Verify all Links
If this bit is set, the verification process checks all
unallocated links; else it only verifies new ports or
component links that have been added to this TE link.
0x04 Data Link Type
If set, the data links to be verified are ports,
otherwise they are component links
VerifyInterval: 16 bits
This is the interval between successive Test messages and is
measured in milliseconds (ms).
MessageId: 32 bits
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgment in the BeginVerifyAck and BeginVerifyNack
messages.
Local TE Link Id: 32 bits
This identifies the TE LinkId of the local node, which may be
numbered or unnumbered (see Flags), for the ports or component
links that are being verified. If this value is set to 0, the
port or component links to be verified are not yet locally
assigned to a TE link.
Remote TE Link Id: 32 bits
This identifies the TE Link Id of the remote node, which may be
numbered or unnumbered (see Flags), for the ports or component
links that are being verified. If this value is set to 0, the
local node has no knowledge of the remote TE Link Id. It is
expected that for unnumbered TE LinkÆs this will be set to 0.
Number of Data Links: 32 bits
This is the number of data links that will be verified.
EncType: 16 bits
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This is the encoding type of the data link and is required for
the purpose of testing where the data links are not required to
be the same encoding type as the control channel. The defined
EncType values are consistent with the Link Encoding Type
values of [OSPF-GEN] and [ISIS-GEN].
Verify Transport Mechanism: 16 bits
This defines the transport mechanism for the Test Messages. The
scope of this bit mask is restricted to each link encoding
type. The local node will set the bits corresponding to the
various mechanisms it can support for transmitting LMP test
messages. The receiver chooses the appropriate mechanism in the
BeginVerifyAck message.
For SONET/SDH Encoding Type, the following flags are defined:
0x01 Capable of communicating using JO overhead bytes.
Test Message is transmitted using the J0 bytes.
0x02 Capable of communicating using Section DCC bytes.
Test Message is transmitted using the DCC Section
Overhead bytes with an HDLC framing format.
0x04 Capable of communicating using Line DCC bytes.
Test Message is transmitted using the DCC Line Overhead
bytes with an HDLC framing format.
0x08 Capable of communicating using POS.
Test Message is transmitted using Packet over SONET
framing using the encoding type specified in the
EncType field.
For GigE Encoding Type, the following flags are defined: TBD
For 10GigE Encoding Type, the following flags are defined: TBD
BitRate: 32 bits
This is the bit rate of the data link over which the Test
messages will be transmitted and is expressed in bytes per
second.
Wavelength: 32 bits
When a data link is assigned to a port or component link that
is capable of transmitting multiple wavelengths (e.g., a fiber
or waveband-capable port), it is essential to know which
wavelength the test messages will be transmitted over. This
value corresponds to the wavelength at which the Test messages
will be transmitted over and is measured in nanometers (nm).
If each data link corresponds to a separate wavelength and
there is no ambiguity as to the wavelength over which the
message will be sent, than this value SHOULD be set to 0.
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9.6.2 BeginVerifyAck Message (MsgType = 6)
When a BeginVerify message is received and Test messages are ready
to be processed, a BeginVerifyAck message MUST be transmitted.
<BeginVerifyAck Message> ::= <Common Header> <BeginVerifyAck>
The BeginVerifyAck object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VerifyDeadInterval | Verify Transport Response |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VerfifyId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the BeginVerify message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the BeginVerify message being negatively acknowledged.
VerifyDeadInterval: 16 bits
If a Test message is not detected within the
VerifyDeadInterval, then a node will send the TestStatusFailure
message for that data link.
Verification Transport Response: 16 bits
It is illegal to set more than one bit in the verification
transport response. The recipient of the BeginVerify message
(and the future recipient of the TEST messages) chooses the
transport mechanism from the various types that are offered by
the transmitter of the Test messages.
VerifyId: 32 bits
This is used to differentiate Test messages from different TE
links and/or LMP peers. The recipient of the BeginVerify
message assigns this value and it MUST node unique. This is a
node-unique value that is assigned by the recipient of the
BeginVerify message.
9.6.3 BeginVerifyNack Message (MsgType = 7)
Lang et al [Page 43]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
If a BeginVerify message is received and a node is unwilling or
unable to begin the Verification procedure, a BeginVerifyNack
message MUST be transmitted.
<BeginVerifyNack Message> ::= <Common Header> <BeginVerifyNack>
The BeginVerifyNack object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code | (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the BeginVerify message being negatively
acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the BeginVerify message being negatively acknowledged.
Error Code: 16 bits
The following values are defined:
1 = Unwilling to verify at this time
2 = TE Link Id configuration error
3 = Unsupported verification transport mechanism
If a BeginVerifyNack message is received with Error Code 1, the node
that originated the BeginVerify SHOULD schedule a BeginVerify
retransmission after Rf seconds, where Rf is a locally defined
parameter.
9.6.4 EndVerify Message (MsgType = 8)
The EndVerify message is sent over the control channel and is used
to terminate the link verification process. The EndVerify message
may be sent at any time a node desires to end the Verify procedure.
The format is as follows:
<EndVerify Message> ::= <Common Header> <EndVerify>
The EndVerify object has the following format:
Lang et al [Page 44]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VerifyId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgement in the EndVerifyAck message.
VerifyId: 32 bits
This is the VerifyId corresponding to the link verification
process that is being terminated.
9.6.5 EndVerifyAck Message (MsgType =9)
The EndVerifyAck message is sent over the control channel and is
used to acknowledge the termination of the link verification
process. The format is as follows:
<EndVerifyAck Message> ::= <Common Header> <EndVerifyAck>
The EndVerifyAck object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the EndVerify message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the EndVerify message being acknowledged.
9.6.6 Test Message
The Test message is transmitted over the data link and is used to
verify its physical connectivity. Unless explicitly stated below,
this is transmitted as an IP packet with payload format as follows:
Lang et al [Page 45]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
<Test Message> ::= <Common Header> <Test>
The Test object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VerifyId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
VerifyId: 32 bits
The VerifyId identifies the link verification procedure with
which the data link verification is associated.
Interface Id: 32 bits
The Interface Id identifies the data link (either port or
component link) over which this message is sent. A valid
Interface Id MUST be nonzero.
Note that this message is sent over a data link and NOT over the
control channel.
9.6.7 TestStatusSuccess Message (MsgType = 10)
The TestStatusSuccess message is transmitted over the control
channel and is used to transmit the mapping between the local
Interface Id and the Interface Id that was received in the Test
message.
<TestStatus Message> ::= <Common Header> <TestStatusSuccess>
The TestStatusSuccess object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Received Interface Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VerifyId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
Lang et al [Page 46]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgement in the TestStatusAck message.
Received Interface Id: 32 bits
This is the value of the Interface Id that was received in the
Test message. A valid Interface Id MUST be nonzero.
Local Interface Id: 32 bits
This is the local value of the Interface Id. A valid Interface
Id MUST be nonzero.
VerifyId: 32 bits
The VerifyId identifies the link verification procedure with
which the data link is associated.
9.6.8 TestStatusFailure Message (MsgType = 11)
The TestStatusFailure message is transmitted over the control
channel and is used to indicate that the Test message was not
received.
<TestStatus Message> ::= <Common Header> <TestStatusFailure>
The TestStatusFailure object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VerifyId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
When combined with the CCId and MsgType, the MessageId field
uniquely identifies a message. This value is incremented and
only decreases when the value wraps. This is used for message
acknowledgement in the TestStatusAck message.
VerifyId: 32 bits
The VerifyId identifies the link verification procedure for
which the timer has expired and no TEST messages have been
received.
Lang et al [Page 47]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
9.6.9 TestStatusAck Message (MsgType = 12)
The TestStatusAck message is used to acknowledge receipt of the
TestStatusSuccess or TestStatusFailure messages.
<TestStatusAck Message> ::= <Common Header> <TestStatusAck>
The TestStatusAck object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the TestStatusSuccess or TestStatusFailure
message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the TestStatusSuccess or TestStatusFailure message being
acknowledged.
9.7 Link Summary Messages
9.7.1 LinkSummary Message (MsgType = 13)
The LinkSummary message is used to synchronize the Interface Ids and
correlate the properties of the TE link. The format of the
LinkSummary message is as follows:
<LinkSummary Message> ::= <Common Header> <LinkSummary>
The LinkSummary Object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (LinkSummary TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
Lang et al [Page 48]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgement in the LinkSummaryAck and LinkSummaryNack
messages.
9.7.1.1 TE Link TLV
The TE Link TLV is TLV Type=3 and is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| 3 | 0xC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Link Mux Cap | Prot. Type | (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Received TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The TE Link TLV is non-negotiable.
Flags: 8 bits
The following flags are defined:
0x01 TE Link Id Type
If this bit is set, the TE Link Id is numbered;
otherwise the TE Link Id is unnumbered.
Link Mux Cap: 8 bits
This is used to identify the associated
multiplexing/demultiplexing capability of the TE link. See
[LSP-HIER].
Protection Type: 8 bits
The Protection Type Flags indicate the link protection, if any,
that is used. Multiple bits may be set when multiple link
protection types are available. The following flags are
defined:
0x01 Extra Traffic
Indicates that the TE link is protecting one or more
(primary) link(s). Any LSPs using a link of this
type will be lost if the primary links being
protected fail.
0x02 Unprotected
Lang et al [Page 49]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
Indicates that the link is unprotected.
0x04 Shared (M:N)
Indicates that the link is protected using a M:N
shared protection scheme.
0x08 Dedicated 1:1
Indicates that the link is protected using a 1:1
dedicated link protection scheme,
0x10 Dedicated 1+1
Indicates that the link is protected using a 1+1
dedicated link protection scheme.
Local TE Link Id: 32 bits
This identifies the TE link of the local node, which may be
numbered or unnumbered (see Flags).
Remote TE Link Id: 32 bits
This identifies the TE link of the remote node, which may be
numbered or unnumbered (see Flags). If the local node has no
knowledge of the remote TE Link Id, this value MUST be set to
0.
9.7.1.2 Data-link TLV
The Data Link TLV is TLV Type=4 and is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| 4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Link Type | (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Received Interface Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Data-link sub-TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Data Link TLV is non-negotiable.
Lang et al [Page 50]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
Length: 16 bits
The Length of the Primary Data Link TLV including all data-link sub-
TLVs.
Flags: 8 bits
The following flags are defined. All other values are
reserved.
0x01 Interface Type: If set, the data link is a port,
otherwise it is a component link.
0x02 Allocated Link: If set, the data link is currently
allocated for user traffic.
Link Type: 8 bits
This is used to identify the encoding type of the data link.
See [OSPF-GEN] or [ISIS-TE].
Local Interface Id: 32 bits
This is the local value of the Interface Id (for the port or
component link) or CCId (for control channel).
Received Interface Id: 32 bits
This is the value of the corresponding Interface Id. If this
is a port or component link, then this is the value that was
received in the Test message. If this is the primary control
channel, then this is the value that is received in all of the
Verify messages.
9.7.1.3 Data Link Sub-TLV
The data link sub-TLV is used to provide characteristics of the
data-bearing links. Currently, there are no data link sub-TLVs
defined.
9.7.2 LinkSummaryAck Message (MsgType = 14)
The LinkSummaryAck message is used to indicate agreement on the
Interface Id synchronization and acceptance/agreement on all the
link parameters. It is on the reception of this message that the
local node makes the TE Link Id associations.
<LinkSummaryAck Message> ::= <Common Header> <LinkSummaryAck>
The LinkSummaryAck object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
Lang et al [Page 51]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flags: 8 bits
The following flags are defined:
0x01 TE Link Id type
If this bit is set, the TE Link Id is numbered;
otherwise the TE Link Id is unnumbered.
MessageId: 32 bits
This is copied from the LinkSummary message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the LinkSummary message being acknowledged.
Local TE Link Id: 32 bits
This identifies the TE Link Id of the local node, which may be
numbered or unnumbered (see Flags).
Remote TE Link Id: 32 bits
This identifies the TE Link Id of the remote node, which may be
numbered or unnumbered (see Flags).
9.7.3 LinkSummaryNack Message (MsgType = 15)
The LinkSummaryNack message is used to indicate disagreement on non-
negotiated parameters or propose other values for negotiable
parameters. Parameters where agreement was reached MUST NOT be
included in the LinkSummaryNack Object.
<LinkSummaryNack Message> ::= <Common Header> <LinkSummaryNack>
The LinkSummaryNack object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lang et al [Page 52]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (LinkSummary TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the LinkSummary message being negatively
acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the LinkSummary message being negatively acknowledged.
The LinkSummary TLVs MUST include acceptable values for all
negotiable parameters. If the LinkSummaryNack includes LinkSummary
TLVs for non-negotiable parameters, they MUST be copied from the
LinkSummary TLVs received in the LinkSummary message.
9.8 Fault Management Messages
9.8.1 ChannelFail Message (MsgType = 16)
The ChannelFail message is sent over the control channel and is used
to notify a neighboring node that a data link (port or component
link) failure has been detected. A neighboring node that receives a
ChannelFail message MUST respond with either a ChannelFailAck or a
ChannelFailNack message indicating that a failure has also been
detected in the corresponding data link in the neighboring node.
The format is as follows:
<ChannelFail Message> ::= <Common Header> <ChannelFail>
The format of the ChannelFail object is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Failure TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lang et al [Page 53]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
MessageId: 32 bits
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgement in the ChannelFailAck and ChannelFailNack
messages.
Local TE Link Id: 32 bits
This is the local TE Link Id for the failed TE link.
If no Failure TLVs are included, the ChannelFail message indicates
the entire TE Link has failed.
9.8.1.2 Failed Channel TLV
The Failed Channel TLV is TLV Type=5. This TLV contains one or more
Failed Channels of a TE link and has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| 5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Local Interface Ids) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Failed Channel TLV is non-negotiable.
Length: 16 bits
The Length has a minimum value of 0x08 and MUST be a multiple
of 4.
Local TE Link Id: 32 bits
This is the local TE Link Id within which the data link has
failed.
Local Interface Id: 32 bits
This is the local Interface Id (either Port Id or Component
Interface Id) of the data link that has failed. This is within
the scope of the TE Link Id. Multiple Local Interface Ids may
be placed into a single Failed Channel TLV if they belong to
the same TE Link.
9.8.2 ChannelFailAck Message (MsgType = 17)
Lang et al [Page 54]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
The ChannelFailAck message is used to indicate that all of the
reported failures in the ChannelFail message also have failures on
the corresponding input channels. The format is as follows:
<ChannelFailureAck Message> ::= <Common Header> <ChannelFailureAck>
The ChannelFailureAck object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the ChannelFail message being acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the ChannelFail message being acknowledged.
9.8.3 ChannelFailNack Message (MsgType = 18)
The ChannelFailNack message is used to indicate that the reported
failures are CLEAR in the upstream node, and hence, the failure has
been isolated between the two nodes.
<ChannelFailNack Message> ::= <Common Header> <ChannelFailNack>
The ChannelFailNack object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Failure TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the ChannelFail message being negatively
acknowledged.
Lang et al [Page 55]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the ChannelFail message being negatively acknowledged.
9.8.4 ChannelActive Message (MsgType = 19)
The ChannelActive message is sent over the control channel and is
used to notify a neighboring node that a data link (port or
component link) is now carrying user data traffic. A
ChannelActiveAck message MUST be sent to acknowledge receipt of the
ChannelActive message. The format is as follows:
<ChannelActive Message> ::= <Common Header> <ChannelActive>
The format of the ChannelActive object is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Link Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Active TLVs) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
When combined with the CCId, the MessageId field uniquely
identifies a message. This value is incremented and only
decreases when the value wraps. This is used for message
acknowledgement in the ChannelActiveAck message.
Local TE Link Id: 32 bits
This is the local TE Link Id within which the data link has
become active.
There MUST be at least one Active TLV.
9.8.4.1 Active Channel TLV
The Active Channel TLV is TLV Type=6. This TLV contains one or more
Active Channels of a TE link and has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lang et al [Page 56]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
|0| 6 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Local Interface Ids) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Active Channel TLV is non-negotiable.
Length: 16 bits
The Length has a minimum value of 0x08 and MUST be a multiple
of 4.
Local Interface Id: 32 bits
This is the local Interface Id (either Port Id or Component
Interface Id) of the data link that has become active. This is
within the scope of the TE Link Id. Multiple Local Interface
Ids may be placed into a single Active Channel TLV if they
belong to the same TE Link.
9.8.5 ChannelActiveAck Message (MsgType = 20)
The ChannelActiveAck message is used to acknowledge receipt of the
ChannelActive message. The format is as follows:
<ChannelActiveAck Message> ::= <Common Header> <ChannelActiveAck>
The ChannelActiveAck object has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MessageId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rcv CCId |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MessageId: 32 bits
This is copied from the ChannelActive message being
acknowledged.
Rcv CCId: 32 bits
This is the Control Channel Id copied from the Common Header of
the ChannelActive message being acknowledged.
Lang et al [Page 57]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
10. Security Considerations
LMP exchanges may be authenticated using the Cryptographic
authentication option. MD5 is currently the only message digest
algorithm specified.
11. References
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3," BCP 9, RFC 2026, October 1996.
[LAMBDA] Awduche, D. O., Rekhter, Y., Drake, J., Coltun, R.,
"Multi-Protocol Lambda Switching: Combining MPLS Traffic
Engineering Control with Optical Crossconnects,"
Internet Draft, draft-awduche-mpls-te-optical-02.txt,
(work in progress), July 2000.
[PERF-MON] Ceuppens, L., Blumenthal, D., Drake, J., Chrostowski,
J., Edwards, W. L., "Performance Monitoring in Photonic
Networks," Internet Draft, draft-ceuppens-mpls-optical-
00.txt, (work in progress), March 2000.
[BUNDLE] Kompella, K., Rekhter, Y., Berger, L., ôLink Bundling in
MPLS Traffic Engineering,ö Internet Draft, draft-
kompella-mpls-bundle-04.txt, (work in progress), November
2000.
[RSVP-TE] Awduche, D. O., Berger, L., Gan, D.-H., Li, T.,
Srinivasan, V., Swallow, G., "Extensions to RSVP for LSP
Tunnels," Internet Draft, draft-ietf-mpls-rsvp-lsp-
tunnel-07.txt, (work in progress), August 2000.
[CR-LDP] Jamoussi, B., et al, "Constraint-Based LSP Setup using
LDP," Internet Draft, draft-ietf-mpls-cr-ldp-03.txt,
(work in progress), September 1999.
[OSPF-TE] Katz, D., Yeung, D., "Traffic Engineering Extensions to
OSPF," Internet Draft, draft-katz-yeung-ospf-traffic-
03.txt, (work in progress), August 2000.
[ISIS-TE] Li, T., Smit, H., "IS-IS extensions for Traffic
Engineering," Internet Draft,draft-ietf-isis-traffic-
02.txt, (work in progress), September 2000.
[OSPF] Moy, J., "OSPF Version 2," RFC 2328, April 1998.
[LMP-DWDM] Fredette, A., Snyder, E., Shantigram, J., et al, ôLink
Management Protocol (LMP) for WDM Transmission Systems,ö
Internet Draft, draft-fredette-lmp-wdm-00.txt, (work in
progress), December 2000.
[MD5] Rivest, R., "The MD5 Message-Digest Algorithm," RFC
1321, April 1992.
[OSPF-GEN] Kompella, K., Rekhter, Y., Banerjee, A., et al, "OSPF
Extensions in Support of Generalized MPLS," Internet
Draft, draft-kompella-ospf-extensions-00.txt, (work in
progress), July 2000.
[ISIS-GEN] Kompella, K., Rekhter, Y., Banerjee, A., et al, "IS-IS
Extensions in Support of Generalized MPLS," Internet
Draft, draft-kompella-isis-extensions-00.txt, (work in
progress), July 2000.
Lang et al [Page 58]
Internet Draft draft-ietf-mpls-lmp-02.txt September 2001
[LSP-HIER] Kompella, K. and Rekhter, Y., ôLSP Hierarchy with MPLS
TE,ö Internet Draft, draft-ietf-mpls-lsp-hierarchy-
01.txt, (work in progress), September 2000.
Lang et al [Page 59]
12. Acknowledgments
The authors would like to thank Ayan Banerjee, George Swallow, Andre
Fredette, and Adrian Farrel for their insightful comments and
suggestions. We would also like to thank John Yu, Suresh Katukan,
and Greg Bernstein for their helpful suggestions for the in-band
control channel applicability.
13. Author's Addresses
Jonathan P. Lang Krishna Mitra
Calient Networks Calient Networks
25 Castilian Drive 5853 Rue Ferrari
Goleta, CA 93117 San Jose, CA 95138
Email: jplang@calient.net email: krishna@calient.net
John Drake Kireeti Kompella
Calient Networks Juniper Networks, Inc.
5853 Rue Ferrari 385 Ravendale Drive
San Jose, CA 95138 Mountain View, CA 94043
email: jdrake@calient.net email: kireeti@juniper.net
Yakov Rekhter Lou Berger
Juniper Networks, Inc. Movaz Networks
385 Ravendale Drive email: lberger@movaz.com
Mountain View, CA 94043
email: yakov@juniper.net
Debanjan Saha Debashis Basak
Tellium Optical Systems Accelight Networks
2 Crescent Place 70 Abele Road, Suite 1201
Oceanport, NJ 07757-0901 Bridgeville, PA 15017-3470
email:dsaha@tellium.com email: dbasak@accelight.com
Hal Sandick Alex Zinin
Nortel Networks Cisco Systems
email: hsandick@nortelnetworks.com 150 W. Tasman Dr.
San Jose, CA 95134
email: azinin@cisco.com
Bala Rajagopalan
Tellium Optical Systems
2 Crescent Place
Oceanport, NJ 07757-0901
email: braja@tellium.com
Lang/Mitra et al [Page 1]
