CCAMP Working Group CCAMP GMPLS P&R Design Team
Internet Draft
Expiration Date: August 2003 J.P. Lang (Editor)
Y. Rekhter (Editor)
February 2003
RSVP-TE Extensions in support of End-to-End GMPLS-based Recovery
draft-lang-ccamp-gmpls-recovery-e2e-signaling-00.txt
Status of this Memo
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Abstract
This document describes protocol specific procedures for GMPLS
(Generalized Multi-Protocol Label Switching) RSVP-TE (Resource
ReserVation Protocol - Traffic Engineering) signaling extensions to
support end-to-end LSP protection and restoration. A generic
functional description of GMPLS recovery can be found in a companion
document.
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1. Contributors
This document is the result of the CCAMP Working Group Protection
and Restoration design team joint effort. Besides the editors, the
following are the authors that contributed to the present memo:
Deborah Brungard (AT&T)
Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA
E-mail: dbrungard@att.com
Sudheer Dharanikota (Consult)
E-mail: sudheer@ieee.org
John Drake (Calient)
25 Castilian Drive
Goleta, CA 93117, USA
E-mail: jdrake@calient.net
Jonathan Lang (Consult)
E-mail: jplang@ieee.org
Guangzhi Li (AT&T)
180 Park Avenue,
Florham Park, NJ 07932, USA
E-mail: gli@research.att.com
Eric Mannie (Consult)
Email: eric_mannie@hotmail.com
Dimitri Papadimitriou (Alcatel)
Fr. Wellesplein, 1
B-2018, Antwerpen, Belgium
Email: dimitri.papadimitriou@alcatel.be
Bala Rajagopalan (Tellium)
2 Crescent Place - P.O. Box 901
Oceanport, NJ 07757-0901, USA
E-mail: braja@tellium.com
Yakov Rekhter (Juniper)
1194 N. Mathilda Avenue
Sunnyvale, CA 94089, USA
E-mail: yakov@juniper.net
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2. Introduction
Generalized MPLS (GMPLS) extends MPLS to include support for Layer-2
(L2SC), time-division multiplex (TDM), lambda switch capable (LSC),
and fiber switch capable (FSC) interfaces. GMPLS-based recovery uses
control plane mechanisms (i.e., signaling, routing, link management
mechanisms) to support data plane fault recovery. In this document,
the term "recovery" is generically used to denote both protection
and restoration; the specific terms "protection" and "restoration"
are only used when differentiation is required. The subtle
distinction between protection and restoration is made based on the
resource allocation done during the recovery period (see [TERM]).
A functional description of GMPLS-based recovery is provided in
[FUNCT] and should be considered a companion document to this
document.
This document describes protocol specific procedures for GMPLS
(Generalized Multi-Protocol Label Switching) RSVP-TE (Resource
ReSerVation Protocol - Traffic Engineering) signaling (see [RFC-
3473] to support end-to-end recovery of an entire LSP from the
initiator to the terminator. In this memo, we address three types of
end-to-end recovery schemes: 1+1 unidirectional protection, 1+1 bi-
directional protection, 1:1 protection, and shared mesh restoration.
The simplest notion of end-to-end protection is 1+1 unidirectional
protection. In this scheme, a protection (primary) LSP is signaled
over a dedicated resource-disjoint alternate path to protect the
working (primary) LSP. Traffic is simultaneously sent on both LSPs
and a selector is used at the egress node to receive traffic from
one of the LSPs. If a failure occurs along one of the LSPs, the
egress node selects the traffic from the valid LSP. No coordination
is required between the end nodes when a failure/switchover occurs.
In 1+1 bi-directional protection, a protection (primary) LSP is
signaled over a dedicated resource-disjoint alternate path to
protect the working (primary) LSP. Traffic is simultaneously sent on
both LSPs and a selector is used at both ingress/egress nodes to
receive traffic from the same LSP. This requires co-ordination
between the end nodes when switching to a protection LSP.
Shared-mesh restoration reduces the pre-provisioned resource
requirements by allowing multiple LSPs to share common link and node
resources. In this scheme, the recovery capacity is pre-reserved,
but explicit action is required to activate (i.e. commit resource
allocation) a specific recovery LSP instantiated during the
provisioning phase. This requires restoration signaling along the
protection path.
Note that crankback and other intermediate recovery signalling will
be addressed in a companion document.
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3. Conventions used in this document:
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
In addition, the reader is assumed to be familiar with the
terminology used in [GMPLS-ARCH], [RFC-3471], [RFC-3473] and
referenced as well as [TERM] and [FUNCT].
4. LSP Identification
LSP tunnels are identified by a combination of the SESSION and
SENDER_TEMPLATE objects (see also [RFC-3209]). The relevant fields
are as follows:
IPv4 (or IPv6) tunnel end point address
IPv4 (or IPv6) address of the egress node for the tunnel.
Tunnel ID
A 16-bit identifier used in the SESSION that remains constant
over the life of the tunnel.
Extended Tunnel ID
A 32-bit (or 16-byte) identifier used in the SESSION that
remains constant over the life of the tunnel. Normally set to
all zeros. Ingress nodes that wish to narrow the scope of a
SESSION to the ingress-egress pair MAY place their IPv4 (or
IPv6) address here as a globally unique identifier.
IPv4 (or IPv6) tunnel sender address
IPv4 (or IPv6) address for a sender node.
LSP ID
A 16-bit identifier used in the SENDER_TEMPLATE and FILTER_SPEC
that can be changed to allow a sender to share resources with
itself.
The first three fields are carried in the SESSION object (Path and
Resv message) and constitute the basic identification of the LSP
tunnel.
The last two fields are carried in the SENDER_TEMPLATE (Path
message) and FILTER_SPEC objects (Resv message). The LSP ID is used
to differentiate LSP tunnels that belong to the same session.
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5. 1+1 Unidirectional Protection
One of the simplest notions of end-to-end protection is 1+1
unidirectional protection.
Consider the following network topology:
A---B---C---D
\ /
E---F---G
The paths [A,B,C,D] and [A,E,F,G,D] are node and link disjoint,
ignoring the ingress/egress nodes A and D. A 1+1 protected LSP is
established from A to D over [A,B,C,D] and [A,E,F,G,D] and traffic
is transmitted simultaneously over both paths (i.e. "LSPs").
When a failure is detected on one path (say at node B), the receiver
at D simply selects the traffic from the other LSP. Note that both
LSPs are instantiated and no resource sharing can be done along the
protection path.
Note: If a failure occurs for instance between link B-C, one should
assume that both paths are SRLG disjoint otherwise such a failure
would impact both working and protection LSPs.
5.1. Identifiers
Since both LSPs correspond to the same session, the SESSION object
MUST be the same in both LSPs. The LSP ID, however, MUST be
different to distinguish between the two LSPs.
A new PROTECTION object is included in the Path message used to
setup the two LSPs. This object carries the desired end-to-end LSP
protection type (in this case, "1+1 Unidirectional") as well as the
LSP ID of the associated LSP.
6. 1+1 Bi-directional Protection
1+1 bi-directional protection is another simple scheme that provides
end-to-end protection.
Consider the following network topology:
A---B---C---D
\ /
E---F---G
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The paths [A,B,C,D] and [A,E,F,G,D] are node and link disjoint,
ignoring the ingress/egress nodes A and D. A bi-directional LSP is
established from A to D over each path and traffic is transmitted
simultaneously over both LSPs. In this scheme, both end-points must
receive traffic over the same LSP. When a failure is detected by one
or both end-points of the LSP, both end-points must select traffic
from the other LSP. This action must be coordinated between node A
and D. Note that both LSPs are instantiated and no resource sharing
can be done along the protection path.
Note: If a failure occurs for instance between link B-C, one should
assume that both paths are SRLG disjoint otherwise such a failure
would impact both working and protection LSPs.
6.1. Identifiers
Since both LSPs correspond to the same session, the SESSION object
MUST be the same in both LSPs. The LSP ID, however, MUST be
different to distinguish between the two LSPs.
A new LSP PROTECTION object is included in the PATH message. This
object carries the desired end-to-end LSP Protection Type (in this
case, "1+1 Bi-directional") as well as the LSP ID of the associated
LSP and referred to as Associated LSP ID.
6.2. End-to-End Switchover Request/Response
To co-ordinate the switchover between endpoints, an end-to-end
switchover request is needed since a failure affecting of one the
paths results in both endpoints switching to the path (or
equivalently the traffic) in their respective direction. This may be
done using the Notify message with a new Error Code indicating
"Working Path Failure; Switchover Request". The Notify Ack message
MUST be sent confirming receipt of the Notify message.
The procedure is as follows:
1. If an end-node (A or D) detects the failure of the working
LSP (or a degradation of signal quality over the working
LSP) or receives a Notify message including its SESSION
object within the <upstream/downstream session list> (see
[RFC-3473]), it MUST begin receiving on the protection LSP
and send a Notify message reliably to the other end-node (D
or A, respectively). This message MAY indicate the identity
of the failed working link and other relevant information
using the IF_ID ERROR_SPEC (see [RFC-3473]).
Note: in this case, the IF_ID ERROR_SPEC replaces the
ERROR_SPEC in the Notify message, otherwise the
corresponding (data plane) information is to be received in
the PathErr/ResvErr message.
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2. Upon receipt of the switchover message, the end-node
(D or A, respectively) MUST begin receiving from the
protection LSP and send a (Notify) Ack message to the other
end-node (A or D, respectively) using reliable message
delivery (see [RFC-2961]).
Since the intermediate nodes (B, C, E, F and G) are assumed to be
GMPLS signalling capable, it has to emphasized that each of them MAY
also generate a Notify message directed either to the LSP initiator
(upstream direction) or the LSP terminator (downstream direction) or
even both. Therefore, it is expected that these LSP terminating
nodes (that also detects the failure of the LSP from the data plane)
provides either the right correlation mechanism to avoid repetition
of the above procedure or just discard subsequent Notify messages
corresponding to the same Session.
Also for 1+1 protected LSP, the Path_State_Remove Flag of the
ERROR_SPEC object (see [RFC-3473] for more details) SHOULD NOT be
set.
7. 1:1 Dedicated Protection (with Extra Traffic)
The most common notion of 1:1 path protection is to route a node-
disjoint primary working LSP and a pre-establish protecting LSP that
is link/node/SRLG disjoint from the primary one. This protects
against working LSP failure(s).
An important feature of GMPLS signalling is that it allows pre-
configuring protecting LSPs to protect working LSPs. This is done by
indicating in the Path message (in the newly defined PROTECTION
object) that the LSP is of type working and protecting,
respectively. Protecting LSPs are used for fast switchover when
working LSPs fail. Note also that both working and protecting LSPs
are primary LSPs.
Although the resources for the protecting LSPs are pre-allocated,
lower priority traffic may use the resources with the caveat that
the lower priority traffic will be preempted if the working LSP
fails. If lower priority traffic is using resources along the
protecting LSPs, the end nodes may need to be notified of the
failure in order to complete the switchover.
The setup of the working LSP SHOULD indicate that the LSP initiator
and terminator wish to receive Notify messages using the Notify
Request object. The upstream node (upstream in terms of the
direction an RSVP Path message traverses) SHOULD send an RSVP Notify
message to the LSP initiator, and the downstream node SHOULD send an
RSVP Notify message to the LSP terminator. Upon receipt of the
Notify messages, the initiator and terminator nodes MUST switch the
traffic from the working LSP to the pre-configured protecting LSP.
Note that if a common initiator-terminator is used for the working
and protecting LSPs no further notification is required to indicate
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that the working LSPs are no longer protected. Note also that both
working and protecting LSPs are working LSPs since fully
instantiated during the provisioning phase.
Consider the following topology:
A---B---C---D
\ /
E---F---G
The path [A,B,C,D] could be protected by [A,E,F,G,D]. Both LSPs are
instantiated (resources are allocated for both working and
protecting LSPs) and no resource sharing can be done along the
protection path since the primary protecting LSP can carry extra-
traffic.
7.1 Identifiers
Since both LSPs correspond to the same session, the SESSION object
MUST be the same in both LSPs. The LSP ID, however, MUST be
different to distinguish between the two LSPs, here the protected
LSP carrying working traffic and the protection LSP that may carry
extra-traffic.
A new PROTECTION object is included in the Path message used to
setup the two LSPs. This object carries the desired end-to-end LSP
protection type (in this case, "1:1 with Extra-Traffic") for the
working LSP by setting both Protection bit and Secondary bit to 0.
The protection LSP is signaled by setting the Protection bit to 1
and the Secondary bit to 0 as well as the LSP ID of the associated
working LSP in the PROTECTION object carried with the Path message.
7.2 End-to-End Switchover Request/Response
To co-ordinate the switchover between endpoints, an end-to-end
switchover request is needed the affected LSP(s) must be moved to
the protecting LSP. Protection switching from the working to the
protecting LSP (implying preemption of extra-traffic carried over
the protecting LSP) must be initiated by one of the end-point nodes
(A or D) or simply end-nodes.
This operation may be done using Notify message exchange with a new
Error Code indicating "Working Path Failure; Switchover Request".
The Notify Ack message MUST be sent confirming receipt of the Notify
message.
The procedure is as follows:
1. If an end-node (A or D) detects the failure of the working
LSP (or a degradation of signal quality over the working
LSP) or receives a Notify message including its SESSION
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object within the <upstream/downstream session list> (see
[RFC-3473]), it disconnects the extra-traffic from the
protecting LSP and send a Notify message reliably to the
other end-node (D or A, respectively). This message MAY
indicate the identity of the failed working link and other
relevant information using the IF_ID ERROR_SPEC (see [RFC-
3473]).
Note: in this case, the IF_ID ERROR_SPEC replaces the
ERROR_SPEC in the Notify message, otherwise the corresponding
information is to be received in the PathErr/ResvErr message
2. Upon receipt of the switchover (i.e. Notify) message, the
end-node (D or A, respectively) MUST disconnect the extra-
traffic from the protecting LSP and begin sending/receiving
normal traffic out/from the protecting LSP and send a
(Notify) Ack message to the other end-node (A or D,
respectively) using reliable message delivery (see [RFC
2961]).
3. Upon receipt of the (Notify) Ack message, the end-node (A or
D, respectively) MUST begin receiving normal traffic from
the protecting LSP.
Note: a 2-phase Automatic Protection Switching (APS) is used in the
present context, 3-phase APS (see [FUNCT]) implying a notification
message and a switchover request/response messages, are left for
further study.
8. End-to-End Bulk Recovery
TBD.
9. Shared Mesh Restoration
An approach to reduce the pre-provisioned resource requirements for
recovery is to have protection LSPs sharing network resources when
the working LSPs that they protect are physically (i.e., link, node,
SRLG, etc.) disjoint. This mechanism is referred to as shared mesh
restoration and is described in [FUNCT]. With shared mesh
restoration, the capacity for the protection LSPs is pre-reserved
and explicit action is required to instantiate the protection LSP.
Consider the following topology:
A---B---C---D
\ /
E---F---G
/ \
H---I---J---K
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The (working) paths [A,B,C,D] and [H,I,J,K] could be protected by
[A,E,F,G,D] and [H,E,F,G,K], respectively. In order to achieve
resource merging during the signalling of these recovery LSPs (i.e.
resource sharing), the LSPs must have the same Session Ids, but the
Session Id includes the target (egress) IP address. These addresses
are not the same in this example. Resource sharing along E, F, G can
only be achieved if the nodes E, F and G recognize that the LSP Type
setting of the secondary LSPs is for protection (see PROTECTION
object) and acts accordingly. In this case, the recovery LSPs are
not merged (which is useful since the paths diverge at G), but the
resources can be shared.
When a failure is detected on one primary working path (say at B),
the error is propagated to the ingress (A) which instantiates the
protection path. At this point, it is important that a failure on
the other path (say at J) does not cause the other ingress (H) to
send the data down the protection path since the resources are
already in use. This can be achieved by node E in two ways. When the
capacity is first reserved for the protecting LSP, E should verify
that the LSPs being protected ([A,B,C,D] and [H,I,J,K],
respectively) do not share any common resources. Second, when a
failure does occur (say at B) and the protecting LSP is
instantiated, E should notify H that the resources for the
protecting LSP are no longer available.
The following sub-sections details how shared mesh restoration can
be implemented in an interoperable fashion using GMPLS RSVP-TE
extensions (see [RFC-3473]). This includes
(1) the ability to identify a "secondary (protecting) LSP" used to
recover another primary (working) LSP (hereby called the
"protected LSP")
(2) the ability to associate the secondary LSP with the protected
LSP
(3) the capability to include information about the resources used
by the protected LSP while establishing the secondary LSP
(4) the ability to instantiate a secondary LSP as an active LSP
when a failure occurs, and
(5) the ability to instantiate several secondary LSPs as activated
LSPs in an efficient manner.
In the following subsections, these features are described in more
detail.
9.1. Identifiers
Since both LSPs (i.e. the primary working and the secondary
protecting LSPs) correspond to the same session, the SESSION object
MUST be the same for both LSPs. The LSP ID, however, MUST be
different to distinguish between the two LSPs.
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9.2 Signaling Primary LSPs
A new PROTECTION object is included in the Path message during
signaling of the primary working LSP. These LSPs are signaled by
setting the Secondary bit of the PROTECTION object to 0. The
PROTECTION object carries the desired end-to-end LSP Protection Type
(in this case, "Shared Mesh") as well as the LSP ID of the
associated LSP if available and otherwise set to 0.
Note also that in the present context, the protected LSP is
considered as working such that the Protection bit of the PROTECTION
object is also set to 0.
9.3 Signaling Secondary LSPs
Secondary LSPs are signaled using the Secondary bit of the
PROTECTION object that is carried in the Path message. If set, the
resources for the secondary LSP should be reserved, but not
committed at the data plane level meaning that the internals of the
switch need not be established until explicit action is taken to
activate the secondary LSP. Activation of a secondary LSP is done
using a Path refresh message with the "Secondary" bit cleared. At
this point, the link and node resources need to be allocated for the
LSP.
Moreover, when used for shared mesh recovery purposes, secondary
LSPs are signaled using the Protection bit of the PROTECTION object.
This object carries the desired end-to-end LSP Protection Type (in
this case, "Shared Mesh") as well as the LSP ID of the associated
primary LSP, which MUST be known before signaling of the secondary
LSP.
Two cases have to be covered here (see also [GMPLS-ARCH]) since the
secondary LSP can be setup with resource reservation but with or
without label pre-selection (both allowing sharing of the recovery
resources). In the former case, secondary LSP signalling does not
necessitate any specific procedure compared to the one defined in
[RFC-3473]. However, in the latter one, label (and thus resource)
re-allocation MAY occur during the secondary LSP activation. This
means that during the activation phase, labels MAY be re-assigned
(with higher precedence over label assignment, see also [RFC-3471]).
10. Full LSP Restoration
Full LSP restoration, on the other hand, switches traffic to an
alternate route around a failure. The new (alternate) route is
selected at the LSP initiator and may reuse intermediate nodes
included in the original LSP route; it may also include additional
intermediate nodes. For strict-hop routing, TE requirements can be
directly applied to the route calculation, and the filed node or
link can be avoided. However, if the failure occurred within a
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loose-routed hop, the source node may not have enough information to
reroute the LSP around the failure.
The alternate route may be calculated on demand (that is, when the
failure occurs) or may be pre-calculated and stored for use when the
failure is reported. This offers faster restoration time. There is,
however, a risk that the alternate route will become out of date
through other changes in the network - this can be mitigated to some
extent by periodic recalculation of idle alternate routes.
Full LSP restoration will be initiated by the node that has isolated
the failure or by the node that has received either an RSVP Notify
message or an RSVP PathErr message indicating that a failure has
occurred. The new resources can be established in a make-before-
break fashion, where the new primary LSP is setup before the old
primary LSP is torn down. This is done by using the mechanisms of
the LSP_Tunnel Session object (see [RFC-3209]) and the Shared-
Explicit reservation style. Both the new and old primary LSPs share
resources at nodes common to both LSPs. The Tunnel end point
addresses, Tunnel Id, Extended Tunnel Id, Tunnel sender address, and
LSP Id are all used to uniquely identify both the old and new LSPs;
this ensures new resources are established without double counting
resource requirements along common segments.
Note that make-before-break is not used to avoid disruption to the
data flow (this has already been broken by the failure that is being
repaired), but is valuable to retain the resources allocated on the
original primary LSP that will be re-used by the new primary LSP.
11. Reversion
TBD.
12. External Commands
This section specifies the control plane behavior when using several
external commands (see [TERM]), typically issued by an operator
through the Network Management System (NMS)/Element Management
System (EMS), which can be used to influence or command the recovery
operations. Other specific commands may complete the below list.
A. Lockout of recovery LSP/span:
A Lockout bit (L) is defined in the ADMIN_STATUS object that follows
the rules defined in Section 8 of [RFC-3471] and Section 7 of [RFC-
3473]. Its usage forces the recovery LSP/span to be temporarily
unavailable to transport traffic (either normal or extra traffic).
B. Lockout of normal traffic:
The Lockout bit (L) usage results in the normal traffic being
temporarily not allowed to be routed over its recovery LSP/span.
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C. Freeze:
TBD.
D. Forced switch for normal traffic:
Recovery signalling is initiated externally that switches normal
traffic to the recovery LSP/span following the procedure defined in
Section 7.
E. Manual switch for normal traffic:
Recovery signalling is initiated externally that switches normal
traffic to the recovery LSP/span following the procedure defined in
Section 7. This, unless a fault condition exists on other LSPs/spans
(including the recovery LSP/span).
13. PROTECTION Object
In this section, we describe extensions to the PROTECTION object to
extend its applicability to end-to-end LSP recovery. In addition to
modifications to the format of the PROTECTION object, we extend its
use so that the object can be included in the Notify message to act
a switchover request for 1+1 and 1:1 bi-directional protection. The
format of the PROTECTION Object (Class-Num = 37, C-Type = TBA by
IANA) 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num(37) | C-Type (TBA) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|P| Reserved | LSP Flags | Reserved | Link Flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Associated LSP ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Secondary (S): 1 bit
When set to 1, this bit indicates that the requested LSP is a
secondary LSP. When set to 0 (default), it indicates that the
requested LSP is a primary LSP.
Protecting (P): 1 bit
When set to 1, this bit indicates that the requested LSP is a
protecting (or recovery) LSP. When set to 0 (default), it
indicates that the requested LSP is a working LSP.
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Reserved: 8 bits
This field is reserved. It MUST be set to zero on transmission
and MUST be ignored on receipt. These bits SHOULD be pass
through unmodified by transit nodes.
LSP (Protection) Flags: 6 bits
Indicates desired end-to-end LSP recovery type. A value of
0 implies that LSP recovery type is left unspecified. Only
one bit can be set at a time. The following values are
defined. All other values are reserved and must be sent as
zero and ignored on receipt.
0x00 Unspecified
0x01 Extra-Traffic
0x02 Unprotected
0x04 Shared Mesh
0x08 Dedicated 1:1 (with Extra Traffic)
0x10 Dedicated 1+1 Unidirectional
0x20 Dedicated 1+1 Bidirectional
Reserved: 10 bits
This field is reserved. It MUST be set to zero on transmission
and MUST be ignored on receipt. These bits SHOULD be pass
through unmodified by transit nodes.
Link Flags: 6 bits
Indicates the desired link protection type (see [RFC-3471]).
Associated LSP ID: 16 bits
Identifies the LSP protected by this LSP. If unknown, this
value is by default set to 0.
Reserved: 16 bits
This field is reserved. It MUST be set to zero on transmission
and MUST be ignored on receipt. These bits SHOULD be pass
through unmodified by transit nodes.
14. PRIMARY PATH ROUTE Object
The PRIMARY PATH (Explicit) ROUTE object (PRRO) is defined to inform
nodes along the path of a secondary LSP about which resources
(link/nodes) are being used by the associated primary LSP (as
specified by the Associated LSP ID field). This object MAY also be
used to inform nodes along the path of a primary protecting LSP
about which resources are being used by the associated primary
working LSP.
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PRR objects carry the EXPLICIT ROUTE object (see [RFC-3209]) of the
LSPs they protect. Therefore, the information included in these
objects MAY be used as policy-based admission control to ensure that
secondary LSPs that are sharing resources have (link/node/SRLG)
disjoint paths for their associated primary LSPs.
14.1. Definition
The primary path route is specified via the PRIMARY_PATH_ROUTE
object (PPRO). The Primary Path Route Class Number is TBA by IANA.
Currently one C-Type (Class-Type) is defined, Type 1 Primary Path
Route. The PRIMARY_PATH_ROUTE object has the following format:
Class-Num = TBA by IANA, C-Type = 1
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Subobjects) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The contents of a PRIMARY_PATH_ROUTE object are a series of
variable-length data items called subobjects. The subobjects are
identical to those that can constitute an EXPLICIT ROUTE object as
defined in [RFC-3209], [RFC-3473] and [RFC-3477].
A Path message may contains multiple PRIMARY_PATH_ROUTE objects,
where each object is meaningful. This is useful when a given
secondary LSP must be link/node/SRLG disjoint from more than one
primary LSP (i.e. is protecting more than one primary LSP).
14.2 Applicability
The PRIMARY_PATH_ROUTE object is to be used only when all GMPLS
nodes along the path support the PRIMARY_PATH_ROUTE object. The
PRIMARY_PATH_ROUTE object is assigned a class value of the form
0bbbbbbb. GMPLS nodes along the path that do not support this object
MUST respond with an "Unknown Object Class" error.
14.3 Subobjects
The contents of a PRIMARY_PATH_ROUTE object is identical to the
EXPLICIT ROUTE object of the primary LSP and thus defined as a list
of variable-length data items called subobjects. Each subobject has
its own length field. The length contains the total length of the
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subobject in bytes, including the Type and Length fields. The length
MUST always be a multiple of 4, and at least 4.
As for the EXPLICIT ROUTE object, the following subobjects are
currently defined for the PRIMARY PATH ROUTE object:
- Sub-Type 1: IPv4 Address (see [RFC 3209])
- Sub-Type 2: IPv6 Address (see [RFC 3209])
- Sub-Type 3: Label (see [RFC-3473])
- Sub-Type 4: Unnumbered Interfaces (see [RFC-3477])
An empty PPRO with no subobjects is considered as illegal. If there
is no first subobject, the corresponding Path message is also in
error and the system SHOULD return a "Bad PRIMARY PATH_ROUTE object"
error.
14.4 Procedures
TBD.
15. Security Considerations
This document does not introduce or imply any specific security
consideration.
16. Acknowledgments
17. IANA Considerations
IANA assigns values to RSVP protocol parameters. Within the current
document a PROTECTION object and a PRIMARY PATH ROUTE object are
defined.
One RSVP Class Number (Class-Num) and two Class Types (C-Types)
values have to be defined by IANA in registry:
http://www.iana.org/assignments/rsvp-parameters
- PROTECTION object: Class-Num = 37, C-Type = 2 (suggested)
- PRIMARY PATH ROUTE object: Class-Num = 23 (suggested), C-
Type = 1 (suggested)
18. Intellectual Property Considerations
This section is taken from Section 10.4 of [RFC2026].
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
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has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances
of licenses to be made available, or the result of an attempt made
to obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification
can be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
19. References
19.1 Normative References
[FUNCT] J.P.Lang and B.Rajagopalan (Editors), "Generalized MPLS
Recovery Functional Specification," Internet Draft,
Work in Progress, draft-ietf-ccamp-gmpls-recovery-
functional-00.txt, January 2002.
[GMPLS-ARCH] E.Mannie (Editor), "Generalized MPLS Architecture",
Internet Draft, Work in progress, draft-ietf-ccamp-
gmpls-architecture-03.txt, August 2002.
[GMPLS-RTG] K.Kompella (Editor), "Routing Extensions in Support of
Generalized MPLS," Internet Draft, Work in Progress,
draft-ietf-ccamp-gmpls-routing-05.txt, August 2002.
[LMP] J.Lang (Editor), "Link Management Protocol (LMP) v1.0"
Internet Draft, Work in progress, draft-ietf-ccamp-lmp-
07, October 2002.
[LMP-WDM] A.Fredette and J.Lang (Editors), "Link Management
Protocol (LMP) for DWDM Optical Line Systems," Internet
Draft, Work in progress, draft-ietf-ccamp-lmp-wdm-
01.txt, September 2002.
[RFC-2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC-2961] L.Berger et al., "RSVP Refresh Overhead Reduction
Extensions", RFC 2961, April 2001.
[RFC-3209] D.Awduche et al., "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
[RFC-3471] L.Berger, (Editor) et al., "Generalized MPLS û
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draft-lang-ccamp-gmpls-recovery-e2e-signaling-00.txt February 2003
Signaling Functional Description", RFC 3471, February
2003.
[RFC-3473] L.Berger (Editor) et al., "Generalized MPLS
Signaling û RSVP-TE Extensions", RFC 3473, February
2003.
[RFC-3477] K.Kompella, and Y.Rekhter, "Signalling Unnumbered
Links in Resource Reservation Protocol - Traffic
Engineering (RSVP-TE)", RFC 3477, January 2003.
[TERM] E.Mannie and D.Papadimitriou (Editors), "Recovery
(Protection and Restoration) Terminology for GMPLS,"
Internet Draft, Work in progress, draft-ietf-ccamp-
gmpls-recovery-terminology-01.txt, November 2002.
19.2 Informative References
[RFC2026] S.Bradner, "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
20. Author's Addresses
Jonathan Lang (Consult)
E-mail: jplang@ieee.org
Yakov Rekhter (Juniper)
1194 N. Mathilda Avenue
Sunnyvale, CA 94089, USA
E-mail: yakov@juniper.net
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J.P.Lang et al. - Internet Draft û Expires August 2003 19