IETF Next Steps in Signaling C. Shen
Internet-Draft H. Schulzrinne
Intended status: Experimental Columbia U.
Expires: August 19, 2010 S. Lee
J. Bang
Samsung AIT
February 15, 2010
NSIS Operation Over IP Tunnels
draft-ietf-nsis-tunnel-09.txt
Abstract
NSIS QoS signaling enables applications to perform QoS reservation
along a data flow path. When the data flow path contains IP tunnel
segments, NSIS QoS signaling has no effect within those tunnel
segments and the resulting QoS-untended tunnel segments could become
the weakest QoS link which may invalidate the QoS efforts in the rest
of the end-to-end path. The problem with NSIS signaling within the
tunnel is caused by the tunnel encapsulation which masks packets'
original IP header fields. Those original IP header fields are
needed to intercept NSIS signaling messages and classify QoS data
packets. This document defines a solution to this problem by mapping
end-to-end QoS session requests to corresponding QoS sessions in the
tunnel, thus extending the end-to-end QoS signaling into the IP
tunnel segments.
Status of this Memo
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This Internet-Draft will expire on August 19, 2010.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 6
3.1. IP Tunneling Protocols . . . . . . . . . . . . . . . . . . 6
3.2. NSIS QoS Signaling in the Presence of IP Tunnels . . . . . 8
4. Design Overview . . . . . . . . . . . . . . . . . . . . . . . 10
4.1. Design Requirements . . . . . . . . . . . . . . . . . . . 10
4.2. Overall Design Approach . . . . . . . . . . . . . . . . . 11
4.3. Tunnel Flow ID for Different IP Tunneling Protocols . . . 14
5. NSIS Operation over Tunnels with Pre-configured QoS
Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. Sender-initiated Reservation . . . . . . . . . . . . . . . 15
5.2. Receiver-initiated Reservation . . . . . . . . . . . . . . 15
6. NSIS Operation over Tunnels with Dynamically Created QoS
Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1. Sender-initiated Reservation . . . . . . . . . . . . . . . 17
6.2. Receiver-initiated Reservation . . . . . . . . . . . . . . 20
7. NSIS-Tunnel Signaling Capability Discovery . . . . . . . . . . 22
7.1. NODE_CAPABILITY Object Format . . . . . . . . . . . . . . 23
7.2. Using NODE_CAPABILITY Object . . . . . . . . . . . . . . . 23
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
9. Security Considerations . . . . . . . . . . . . . . . . . . . 24
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
11.1. Normative References . . . . . . . . . . . . . . . . . . . 25
11.2. Informative References . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27
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1. Introduction
IP tunneling is a technique that allows a packet to be encapsulated
and carried as payload within an IP packet. The resulting
encapsulated packet is called an IP tunnel packet, and the packet
being tunneled is called the original packet. In typical scenarios,
IP tunneling is used to exert explicit forwarding path control (e.g.,
in Mobile IP [RFC3220]), facilitate the secure IP delivery
architecture (e.g., in IPSEC [RFC2401]), and help packet routing in
IP networks of different characteristics (e.g., between IPv6 and IPv4
networks [RFC4213]).
This document considers the situation when the packet being tunneled
contains a Next Step In Signaling (NSIS) [RFC4080] message. NSIS is
an IP network layer signaling architecture consisting of a Generic
Internet Signaling Transport (GIST) [I-D.ietf-nsis-ntlp] sub-layer
for signaling transport, and an NSIS Signaling Layer Protocol (NSLP)
sub-layer customizable for different applications. We focus on the
Quality of Service (QoS) NSLP [I-D.ietf-nsis-qos-nslp] which provides
functionalities that extend those of the earlier RSVP [RFC2205]
signaling. In this document the term "NSIS" and "NSIS QoS" are used
interchangeably.
Without additional efforts, NSIS signaling does not work within IP
tunneling segments of a signaling path. The reason is that tunnel
encapsulation masks the original packet including its header and
payload. However, information from the original packet is required
both for NSIS peer node discovery and for QoS data flow packet
classification. Without access to information from the original
packet, an IP tunnel acts as an NSIS-unaware virtual link in the end-
to-end NSIS signaling path.
This document defines a mechanism to extend end-to-end NSIS signaling
for QoS reservation into IP tunnels. The NSIS-aware IP tunnel end-
points that support this mechanism are called NSIS-tunnel-aware end-
points. There are two main operation modes. On one hand, if the
tunnel already has pre-configured QoS sessions, the NSIS-tunnel-aware
end-points map end-to-end QoS signaling requests directly to existing
tunnel sessions as long as there are enough tunnel session resources;
on the other hand, if no pre-configured tunnel QoS sessions are
available, the NSIS-tunnel-aware end-points dynamically initiate and
maintain tunnel QoS sessions that are then associated with the
corresponding end-to-end QoS sessions. Note that whether the tunnel
pre-configures QoS sessions or not, and which pre-configured tunnel
QoS sessions a particular end-to-end QoS signaling request should be
mapped to are policy issues out of scope of this document.
The rest of this document is organized as follows. Section 2 defines
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terminology. Section 3 presents the problem statement including
common IP tunneling protocols and existing behavior of NSIS QoS
signaling operating over IP tunnels. Section 4 introduces the design
requirements and overall approach of our mechanism. More details
about how NSIS QoS signaling operates with tunnels that use pre-
configured QoS and dynamic QoS signaling are provided in Section 5
and Section 6. Section 7 describes a method to automatically
discover whether a tunnel end-point node supports the NSIS-tunnel
interoperation mechanism defined in this document. Section 8
discusses IANA considerations and Section 9 considers security.
2. Terminology
This document uses terminology defined in [RFC2473],
[I-D.ietf-nsis-ntlp], and [I-D.ietf-nsis-qos-nslp]. In addition, the
following terms are used:
Tunnel IP Header: The IP header prepended to the original packet
during encapsulation. It specifies the tunnel end-points as
source and destination.
Tunnel Specific Header: The header fields inserted by the
encapsulation mechanism after the tunnel IP header and before the
original packet. These headers may or may not exist depending on
the specific tunnel mechanism used.
Tunnel Intermediate Node (Tmid): A node which resides in the middle
of the forwarding path between the tunnel entry-point node and the
tunnel exit-point node.
IP Tunnel: A tunnel configured as a virtual link between two IP
nodes, on which the encapsulating protocol is IP.
Flow Identifier (Flow ID): The set of header fields which is used to
identify a [Data] flow. For example, it may include flow sender
and receiver addresses, protocol and port numbers.
End-to-end [QoS] Signaling: The signaling process that manipulates
the QoS control information in the end-to-end path from the flow
sender to the flow receiver. When the end-to-end flow path
contains tunnel segments, this document uses end-to-end [QoS]
signaling to refer specially to the [QoS] signaling outside the
tunnel segments.
Tunnel [QoS] Signaling: The signaling process that manipulates the
QoS control information in the path inside a tunnel, between the
tunnel entry-point and the tunnel exit-point nodes.
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[Adjacent] NSIS Peer: The next node along the signaling path, in the
upstream or downstream direction, with which a NSIS node
explicitly interacts.
NSIS-aware Node: A node that supports NSIS signaling.
NSIS-aware Tunnel End-point Node: A tunnel end-point node which is
also an NSIS node.
NSIS-tunnel-aware [Tunnel] End-point Node: An NSIS-aware Tunnel End-
point node which also supports the mechanism for NSIS operating
over IP tunnels defined in this document.
3. Problem Statement
3.1. IP Tunneling Protocols
Tunnel from node B to node D
<---------------------->
Tunnel Tunnel Tunnel
Entry-Point Intermediate Exit-Point
Node Node Node
+-+ +-+ +-+ +-+ +-+
|A|-->--//-->--|B|=====>====|C|===//==>===|D|-->--//-->--|E|
+-+ +-+ +-+ +-+ +-+
Original Original
Packet Packet
Source Destination
Node Node
Figure 1: IP Tunnel
The following definition of IP tunneling is derived from [RFC2473]
and adapted for both IPv4 and IPv6.
IP tunneling is a technique for establishing a "virtual link" between
two IP nodes for transmitting data packets as payloads of IP packets
(see Figure 1). From the point of view of the two nodes, this
"virtual link", called an IP tunnel, appears as a point-to-point link
on which IP acts like a link-layer protocol. The two IP nodes play
specific roles. One node encapsulates original packets received from
other nodes or from itself and forwards the resulting tunnel packets
through the tunnel. The other node decapsulates the received tunnel
packets and forwards the resulting original packets towards their
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destinations, possibly itself. The encapsulating node is called the
tunnel entry-point node (Tentry), and it is the source of the tunnel
packets. The decapsulating node is called the tunnel exit-point node
(Texit), and it is the destination of the tunnel packets.
An IP tunnel is a unidirectional mechanism - tunnel packet flow takes
place in one direction between the IP tunnel entry-point and exit-
point nodes (see Figure 1). Bi-directional tunneling is achieved by
combining two unidirectional mechanisms, that is, configuring two
tunnels, each in opposite direction to the other - the entry-point
node of one tunnel is the exit-point node of the other tunnel.
Figure 2 illustrates the original packet and the resulting tunnel
packet. In a tunnel packet, the original packet is encapsulated
within the tunnel header. The tunnel header contains two components,
the tunnel IP header and other tunnel specific headers. The tunnel
IP header specifies tunnel entry-point node as IP source address and
tunnel exit-point node as IP destination address, thus causing the
tunnel packet to be routed inside the tunnel. The tunnel specific
headers in between the tunnel IP header and the original packet in a
tunnel packet are optional, depending on the tunneling protocol in
use.
+----------------------------------//-----+
| Original | |
| | Original Packet Payload |
| Header | |
+----------------------------------//-----+
< Original Packet >
|
v
< Tunnel Headers > < Original Packet >
+---------+-----------+-------------------------//--------------+
| Tunnel | Tunnel | |
| IP | Specific | Original Packet |
| Header | Headers | |
+---------+-----------+-------------------------//--------------+
< Tunnel IP Packet >
Figure 2: IP Tunnel Encapsulation
Commonly used IP tunneling protocols include Generic Routing
Encapsulation (GRE) [RFC1701][RFC2784], Generic Routing Encapsulation
over IPv4 Networks (GREIPv4) [RFC1702] and IP Encapsulation within IP
(IPv4INIPv4) [RFC1853][RFC2003], Minimal Encapsulation within IP
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(MINENC) [RFC2004], IPv6 over IPv4 Tunneling (IPv6INIPv4) [RFC4213],
Generic Packet Tunneling in IPv6 Specification (IPv6GEN) [RFC2473]
and IPSEC tunneling mode (IPSEC) [RFC4301][RFC4303]. Among these
tunneling protocols, the tunnel headers in IPv4INIPv4, IPv6INIPv4 and
IPv6GEN contain only a tunnel IP header, and no tunnel specific
headers. All the other tunneling protocols have a tunnel header
consisting of both a tunnel IP header and a tunnel specific header.
The tunnel specific header is the GRE header for GRE and GREIPv4, the
minimum encapsulation header for MINENC and the Encapsulation
Security Payload (ESP) header for IPSEC tunneling mode. As will be
discussed in Section 4.3, some of the tunnel specific headers may be
used to identify a flow in the tunnel and facilitate NSIS operating
over IP tunnels.
3.2. NSIS QoS Signaling in the Presence of IP Tunnels
Typically, applications use NSIS QoS signaling to reserve resources
for a flow along the flow path. NSIS QoS signaling can be initiated
by either the flow sender or flow receiver. Figure 3 shows an
example scenario with five NSIS nodes, including flow sender node A,
flow receiver node E, and intermediate NSIS nodes B, C and D. Nodes
which are not NSIS QoS capable are not shown.
NSIS QoS NSIS QoS NSIS QoS NSIS QoS NSIS QoS
Node Node Node Node Node
+-+ +-+ +-+ +-+ +-+
|A|-->--//-->--|B|----->----|C|---//-->---|D|-->--//-->--|E|
+-+ +-+ +-+ +-+ +-+
Flow Flow
Sender Receiver
Node Node
Figure 3: Example Scenario of NSIS QoS Signaling
Figure 4 illustrates a sender-initiated signaling sequence in the
scenario of Figure 3. Sender node A sends a RESERVE message towards
receiver node E. The RESERVE message gets forwarded by intermediate
NSIS Nodes B, C, and D and finally reaches receiver node E. Receiver
node E then sends back a RESPONSE message confirming the QoS
reservation, again through the previous intermediate NSIS nodes in
the data flow path.
There are two important aspects in the above signaling process that
are worth mentioning. First, the flow sender does not initially know
exactly which intermediate nodes are NSIS-aware and should be
involved in the signaling process for a flow from node A to node E.
Discovery of those nodes, namely node B, C and D is accomplished by a
separate NSIS peer discovery process (not shown above, see
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[I-D.ietf-nsis-ntlp]). The NSIS peer discovery messages contain
special IP header and payload format or include a Router Alert Option
(RAO) [RFC2113] [RFC2711]. The special formats of NSIS discovery
messages allow node B, C and D to intercept them and subsequently
insert themselves into the signaling path for the flow in question.
After formation of the signaling path, all signaling messages
corresponding to this flow will be passed to these nodes for
processing. Other nodes which are not NSIS-aware simply forward all
signaling messages like any other IP packets without additional
handling.
Node A Node B Node C Node D Node E
| | | | |
| RESERVE | | | |
+------------->| | | |
| | RESERVE | | |
| +------------->| | |
| | | RESERVE | |
| | +------------->| |
| | | | RESERVE |
| | | +------------->|
| | | | RESPONSE |
| | | |<-------------+
| | | RESPONSE | |
| | |<-------------+ |
| | RESPONSE | | |
| |<-------------+ | |
| RESPONSE | | | |
|<-------------+ | | |
| | | | |
| | | | |
Figure 4: Sender-initiated NSIS QoS Signaling
Second, the goal of QoS signaling is to install control information
to give QoS treatment for the flow being signaled. Basic QoS control
information includes the data Flow ID for packet classification and
the type of QoS treatment those packets are entitled to. The Flow ID
contains a set of header fields such as flow sender and receiver
addresses, protocol and port numbers.
Now consider Figure 5 where nodes B, C and D are end-points and
intermediate nodes of an IP tunnel. During the signaling path
discovery process, node B can still intercept and process NSIS peer
discovery messages if it recognizes them before performing tunnel
encapsulation; node D can identify NSIS peer discovery messages after
performing tunnel decapsulation. A tunnel intermediate node such as
node C, however, only sees the tunnel header of the packets and will
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not be able to identify the original NSIS peer discovery message or
insert itself in the flow signaling path. Furthermore, the Flow ID
of the original flow is based on IP header fields of the original
packet. Those fields are also hidden in the payload of the tunnel
packet. So there is no way node C can classify packets belonging to
that flow in the tunnel. In summary, the problem is that tunnel
intermediate nodes are unable to intercept original NSIS signaling
messages and unable to classify original data flow packets as a
result of tunnel encapsulation. An IP tunnel segment appears just
like a QoS-unaware virtual link. Since the best QoS of an end-to-end
path is judged based on its weakest segment, leaving the tunnel path
"untended" risks voiding other efforts to provide QoS in the rest of
the path.
Tunnel from node B to node D
<---------------------->
Tunnel Tunnel Tunnel
Entry-Point Intermediate Exit-Point
NSIS QoS NSIS QoS NSIS QoS NSIS QoS NSIS QoS
Node Node Node Node Node
+-+ +-+ +-+ +-+ +-+
|A|-->--//-->--|B|=====>====|C|===//==>===|D|-->--//-->--|E|
+-+ +-+ +-+ +-+ +-+
Flow Flow
Sender Receiver
Node Node
Figure 5: Example Scenario of NSIS QoS Signaling with IP Tunnel
4. Design Overview
4.1. Design Requirements
We identify the following design requirements for NSIS operating over
IP tunnels.
o The mechanism should work with all common IP tunneling protocols
listed in Section 3.1.
o Some IP tunnels maintain pre-configured QoS sessions inside the
tunnel. The mechanism should work for IP tunnels both with and
without pre-configured tunnel QoS sessions.
o The mechanism should minimize the required upgrade to existing
infrastructure in order to facilitate its deployment.
Specifically, we limit the necessary upgrade to NSIS-aware tunnel
end-points. Only tunnel end-points need to support the mechanism
defined in this document. Such tunnel end-points are called NSIS-
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tunnel-aware end-points. All other nodes, both inside and outside
the tunnel should be transparent to this mechanism.
o The mechanism should facilitate its incremental deployment by
providing a method for one NSIS-tunnel-aware end-point to discover
whether the other end-point is also NSIS-tunnel-aware.
o The mechanism should learn from design experience of previous work
on RSVP over IP tunnels (RSVP-TUNNEL) [RFC2746], while also
addressing the following major differences of NSIS from RSVP.
First, NSIS is designed as a generic framework to accommodate
various signaling application needs, and therefore is split into a
signaling transport layer and a signaling application layer; RSVP
does not have a layer split and is designed only for QoS
signaling. Second, NSIS QoS NSLP allows both sender-initiated and
receiver-initiated reservations; RSVP only supports receiver-
initiated reservations. Third, NSIS deals only with unicast; RSVP
also supports multicast. Fourth, NSIS integrates a new Session ID
feature which is different from the session identification concept
in RSVP.
4.2. Overall Design Approach
The overall design of this NSIS signaling and IP tunnel interworking
mechanism draws similar concepts from RSVP-TUNNEL [RFC2746], but is
tailored and extended for NSIS operation.
Since a flow is considered unidirectional, to accommodate flows in
both directions of a tunnel, we require both tunnel entry-point and
tunnel exit-point to be NSIS-tunnel-aware. If an NSIS-tunnel-aware
end-point needs to know whether the other tunnel end-point is also
NSIS-tunnel-aware, it may use the NSIS-tunnel capability discovery
mechanism defined in Section 7.
Tunnel end-points need to always intercept NSIS peer discovery
messages and insert themselves into the NSIS signaling path so they
can receive all NSIS signaling messages and coordinate their
interaction with tunnel QoS.
To facilitate the QoS handling in the tunnel, the end-to-end QoS
session will be mapped to a tunnel QoS session, either pre-configured
or dynamically created. An important property of a tunnel QoS
session is its tunnel Flow ID which identifies the end-to-end data
flow within the tunnel. In both tunnels with and without pre-
configured QoS sessions, the tunnel Flow ID is assigned based on
information available in the tunnel header, therefore solving the
problem for tunnel-intermediate nodes to classify flow packets as
discussed in Section 3.2. An example tunnel Flow ID contains the
tunnel entry-point and exit-point IP addresses and a tunnel inserted
UDP port number. We discuss more details about recommended choices
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of tunnel Flow ID for different IP tunneling protocols in
Section 4.3.
For tunnels that maintain pre-configured QoS sessions, upon receiving
a request to reserve resources for an end-to-end session, the tunnel
end-point maps the end-to-end QoS session to an existing tunnel
session. To simplify the design, the mapping decision is always made
by the tunnel entry-point regardless of whether the end-to-end
session uses sender-initiated or receiver-initiated NSIS signaling
mode. The details about which end-to-end session can be mapped to
which pre-configured tunnel session depend on policy mechanisms
outside the scope of this document.
For tunnels that do not maintain pre-configured QoS sessions, the
NSIS-tunnel-aware end-points dynamically create and manage a
corresponding tunnel QoS session for the end-to-end session. Since
the initiation mode of both QoS sessions can be sender-initiated or
receiver-initiated, to simplify the design, we require that the
initiation mode of the tunnel QoS session follow that of the end-to-
end QoS session. In other words, the end-to-end QoS session and its
corresponding tunnel QoS session are either both sender-initiated or
both receiver-initiated. To keep the handling mechanism consistent
with the case for tunnels with pre-configured QoS sessions, the
tunnel entry-point always initiates the mapping between the tunnel
session and the end-to-end session.
As the mapping initiator, the tunnel entry-point records the
association between the end-to-end session and its corresponding
tunnel session, both in tunnels with and without pre-configured QoS
sessions. This association serves two purposes, one at the signaling
plane and the other at the data plane. At the signaling plane, the
association enables the tunnel entry-point to coordinate necessary
interaction, such as QoS adjustment in sender-initiated reservations,
between the end-to-end and the tunnel QoS sessions. At the data
plane, the association allows the tunnel entry-point to correctly
encapsulate data flow packets according to the chosen tunnel Flow ID.
Since the tunnel Flow ID uses header fields that are visible inside
the tunnel, the tunnel intermediate nodes can classify the data flow
packets and apply appropriate QoS treatment.
In addition to the tunnel entry-point recording the association
between the end-to-end session and its corresponding tunnel session,
the tunnel exit-point also needs to maintain the same association for
similar reasons. At the signaling plane, this association at the
tunnel exit-point enables the interaction of the end-to-end and the
tunnel QoS session such as QoS adjustment in receiver-initiated
reservations. At the data plane, this association tells the tunnel
exit-point that the relevant data flow packets need to be
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decapsulated according to the corresponding tunnel Flow ID.
The tunnel exit-point learns about the mapping between the tunnel and
the end-to-end QoS sessions, including the tunnel Flow ID and the
tunnel session's Session ID that corresponds to the end-to-end
session, through the follow methods. In tunnels with pre-configured
QoS sessions, the mapping information between the corresponding
tunnel and end-to-end QoS sessions may be pre-configured as well. In
tunnels without pre-configured QoS sessions, the tunnel exit-point
knows the tunnel Flow ID through the NSIS signaling process that
creates the tunnel QoS sessions inside the tunnel. Meanwhile, the
tunnel exit-point maps the Session IDs of the tunnel QoS session and
the end-to-end session through the QoS NSLP BOUND_SESSION_ID object
[I-D.ietf-nsis-qos-nslp]. Specifically, when used for NSIS signaling
over IP tunnels, the BOUND_SESSION_ID object carries the Session ID
of the tunnel session and a Binding Code of value 0x01 indicating
tunnel handling. The tunnel entry-point includes this tunnel binding
object in appropriate end-to-end signaling messages. Upon receiving
this binding object, the tunnel exit-point records the association
between the tunnel QoS session and the corresponding end-to-end QoS
session.
One problem for NSIS operating over IP tunnels which dynamically
create QoS sessions is that it involves two signaling sequences. The
outcome of the tunnel signaling session directly affects the outcome
of the end-to-end signaling session. Since the two signaling
sessions overlap in time, there are circumstances when a tunnel end-
point has to decide whether it should proceed with the end-to-end
signaling session while it is still waiting for results of the tunnel
session. Sequential mode and parallel mode are two basic options for
this problem. In sequential mode, end-to-end signaling pauses when
it is waiting for results of tunnel signaling, and resumes upon
receipt of the tunnel signaling outcome. In parallel mode, end-to-
end signaling continues outside the tunnel while tunnel signaling is
still in process and its outcome is unknown. The parallel mode may
lead to reduced signaling delays if the QoS resources in the tunnel
path are sufficient compared to the rest of the end-to-end path. If
the QoS resources in the tunnel path are more constraint than the
rest of the end-to-end path, however, the parallel mode may lead to
wasted end-to-end signaling or necessitates re-negotiation after the
tunnel signaling outcome becomes available. In those cases, the
signaling flow of the parallel mode also tends to be more
complicated. This document adopts a sequential mode approach. In
addition, the actual signaling process uses the QoS NSLP message
binding mechanism [I-D.ietf-nsis-qos-nslp] to convey the dependency
relationship between corresponding messages of the tunnel session and
the end-to-end session.
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4.3. Tunnel Flow ID for Different IP Tunneling Protocols
A tunnel Flow ID identifies the end-to-end flow for packet
classification within the tunnel. The tunnel Flow ID is based on a
set of tunnel header fields. Different tunnel Flow ID can be chosen
for different tunneling mechanisms in order to minimize the
classification overhead. This document specifies the following Flow
ID formats for the respective tunneling protocols.
o For IPv6 tunneling protocols (IPv6GEN), the tunnel Flow ID
consists of the tunnel entry-point IPv6 address and the tunnel
exit-point IPv6 address plus a unique IPv6 flow label [RFC3697].
o For IPSEC tunnel mode (IPSEC), the tunnel Flow ID contains the
tunnel entry-point IP address and the tunnel exit-point IP address
plus the Security Parameter Index (SPI).
o For all other tunneling protocols (GRE, GREIPv4, IPv4INIPv4,
MINENC, IPv6INIPv4), the tunnel entry-point inserts an additional
UDP header between the tunnel header and the original packet. The
Flow ID consists of the tunnel entry-point and tunnel exit-point
IP addresses and the source port number in the additional UDP
header. In these cases, it is especially important that the
tunnel exit-point also understands the additional UDP
encapsulation, and therefore can correctly decapsulate both the
normal tunnel header and the additional UDP header. In other
words, both tunnel end-points need to be NSIS-tunnel-aware.
The above recommendations about choosing tunnel Flow ID apply to
dynamically created QoS tunnel sessions. For pre-configured QoS
tunnel sessions, the corresponding Flow ID is determined by the
configuration mechanism itself. For example, if the tunnel QoS is
DiffServ based, the DiffServ Code Point (DSCP) field value may be
used to identify the corresponding tunnel session.
5. NSIS Operation over Tunnels with Pre-configured QoS Sessions
When tunnel QoS is managed by pre-configured QoS sessions, both the
tunnel entry-point and tunnel exit-point also need to be configured
with the Flow ID of the tunnel QoS session. This is to enable the
tunnel end-points to correctly perform matching encapsulating and
decapsulating operations. The procedures of NSIS operating over
tunnels with pre-configured QoS sessions are slightly different
depending on whether the end-to-end NSIS signaling is sender-
initiated or receiver-initiated. But in either case, it is the
tunnel entry-point that first creates the mapping between a tunnel
session and an end-to-end session.
5.1. Sender-initiated Reservation
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Figure 6 illustrates the signaling sequence when end-to-end signaling
outside the tunnel is sender-initiated. Upon receiving a RESERVE
message from the sender, Tentry checks tunnel QoS configuration,
determines whether and how this end-to-end session can be mapped to a
pre-configured tunnel session. The mapping criteria are part of the
pre-configuration and outside the scope of this document. Tentry
then tunnels the RESERVE message to Texit. Texit forwards the
RESERVE message to the receiver. The receiver replies with a
RESPONSE message which arrives at Texit, Tentry and finally the
sender. If the RESPONSE message that Tentry receives confirms that
the overall signaling is successful, Tentry starts to encapsulate all
incoming packets of the data flow using the tunnel Flow ID
corresponding to the mapped tunnel session. Texit knows how to
decapsulate the tunnel packets because it recognizes the mapped
tunnel Flow ID based on information supplied during tunnel session
pre-configuration.
Sender Tentry Tmid Texit Receiver
| | | | |
| RESERVE | | | |
+------------->| | | |
| | RESERVE | |
| +---------------------------->| |
| | | | RESERVE |
| | | +------------->|
| | | | RESPONSE |
| | | |<-------------+
| | RESPONSE | |
| |<----------------------------+ |
| RESPONSE | | | |
|<-------------+ | | |
| | | | |
| | | | |
Figure 6: Sender-initiated End-to-end Session with Pre-configured
Tunnel QoS Sessions
5.2. Receiver-initiated Reservation
Figure 7 shows the signaling sequence when end-to-end signaling
outside the tunnel is receiver-initiated. Upon receiving the first
end-to-end Query message, Tentry examines the tunnel QoS
configuration, updates and tunnels the Query message to Texit. Texit
decapsulates the QUERY message, processes it and forwards it toward
the receiver. Later, the receiver sends back a RESERVE message
passing through Texit and arriving at Tentry. Tentry decides on
whether and how the QoS request for this end-to-end session can be
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mapped to a pre-configured tunnel session based on an algorithm
outside the scope of this document. Then Tentry tunnels the RESERVE
message to Texit which forwards it to the receiver. The signaling
continues until a RESPONSE message arrives at Tentry, Texit and
finally the receiver. If the RESPONSE message that Tentry receives
confirms that the overall signaling is successful, Tentry starts to
encapsulate all incoming packets of the data flow using the tunnel
Flow ID corresponding to the mapped tunnel session. Similarly, Texit
knows how to decapsulate the tunnel packets because it recognizes the
mapped tunnel Flow ID based on information supplied during tunnel
session pre-configuration.
Sender Tentry Tmid Texit Receiver
| | | | |
| QUERY | | | |
+------------->| | | |
| | QUERY | |
| +---------------------------->| |
| | | | QUERY |
| | | +------------->|
| | | | RESERVE |
| | | |<-------------+
| | RESERVE | |
| |<----------------------------+ |
| RESERVE | | | |
|<-------------+ | | |
| RESPONSE | | | |
+------------->| | | |
| | RESPONSE | |
| +---------------------------->| |
| | | | RESPONSE |
| | | +------------->|
| | | | |
| | | | |
Figure 7: Receiver-initiated End-to-end Session with Pre-configured
Tunnel QoS Sessions
Since tunnel QoS signaling is not involved in pre-configured QoS
tunnels, Figure 6 and Figure 7 look as if the tunnel is a single
virtual link. The signaling path simply skips all tunnel
intermediate nodes. However, both Tentry and Texit need to deploy
NSIS-tunnel related functionalities described above, including acting
on the end-to-end NSIS signaling messages based on tunnel QoS status,
mapping end-to-end and tunnel QoS sessions, and correctly
encapsulating and decapsulating tunnel packets according to the
tunnel protocol and the configured tunnel Flow ID.
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6. NSIS Operation over Tunnels with Dynamically Created QoS Sessions
When there are no pre-configured tunnel QoS sessions, a tunnel can
apply the same NSIS QoS signaling mechanism used for the end-to-end
path to manage the QoS inside the tunnel. The tunnel NSIS signaling
involves only those NSIS nodes in the tunnel forwarding path. The
Flow IDs for the tunnel signaling are based on tunnel header fields.
NSIS peer discovery messages inside the tunnel distinguish themselves
using the tunnel header fields, which solves the problem for tunnel
intermediate NSIS nodes to intercept signaling messages.
When tunnel end-points dynamically create tunnel QoS sessions, the
initiation mode of the tunnel session always follows the initiation
mode of the end-to-end session. Specifically, when the end-to-end
session is sender-initiated, the tunnel session should also be
sender-initiated; when the end-to-end session is receiver-initiated,
the tunnel session should also be receiver-initiated.
The tunnel entry-point conveys the corresponding tunnel Flow ID
associated with an end-to-end session to the tunnel exit-point during
the tunnel signaling process. The tunnel entry-point also informs
the binding between the corresponding tunnel session and the end-to-
end session to the exit-point through the BOUND_SESSION_ID QoS NSLP
message object. The reservation message dependencies between the
tunnel session and end-to-end session is resolved using the MSG_ID
and BOUND_MSG_ID objects of the QoS NSLP message binding mechanism.
6.1. Sender-initiated Reservation
Figure 8 shows the typical messaging sequence of how NSIS operates
over IP tunnels when both end-to-end session and tunnel session are
sender-initiated. Tunnel signaling messages are distinguished from
end-to-end messages by a prime symbol after the message name. The
sender first sends an end-to-end RESERVE message (1) which arrives at
Tentry. Tentry chooses the tunnel Flow ID, creates the tunnel
session and associates the end-to-end session with the tunnel
session. Tentry then sends a tunnel RESERVE' message (2) matching
the request of the end-to-end session towards Texit to reserve tunnel
resources. This RESERVE' message (2) includes a MSG_ID object which
contains a randomly generated 128-bit MSG_ID. Meanwhile, Tentry
inserts a BOUND_MSG_ID object containing the same MSG_ID as well as a
BOUND_SESSION_ID object containing the Session ID of the tunnel
session into the original RESERVE message, and sends this RESERVE
message (3) towards Texit using normal tunnel encapsulation. The
Message_Binding_Type flag of both the MSG_ID and BOUND_MSG_ID objects
in the RESERVE' and RESERVE messages (2, 3) is SET, indicating a
bidirectional binding. The tunnel RESERVE' message (2) is processed
hop-by-hop inside the tunnel for the flow identified by the chosen
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tunnel Flow ID, while the end-to-end RESERVE message (3) passes
through the tunnel intermediate nodes (Tmid) just like other tunneled
packets. These two messages could arrive at Texit in different
orders, and the reaction of Texit in these different situations
should combine the tunnel QoS message processing rules with the QoS
NSLP processing principles for message binding
[I-D.ietf-nsis-qos-nslp], as illustrated below.
Sender Tentry Tmid Texit Receiver
| | | | |
| RESERVE(1) | | | |
+------------->| | | |
| | RESERVE'(2) | | |
| +=============>| | |
| | | RESERVE'(2) | |
| | +=============>| |
| | RESERVE(3) | |
| +---------------------------->| |
| | | RESPONSE'(4) | |
| | |<=============+ |
| | RESPONSE'(4) | | |
| |<=============+ | |
| | | | RESERVE(5) |
| | | +------------->|
| | | | RESPONSE(6) |
| | | |<-------------+
| | RESPONSE(6) | |
| |<----------------------------+ |
| RESPONSE(6) | | | |
|<-------------+ | | |
| | | | |
| | | | |
(1,5): RESERVE w/o BOUND_MSG_ID and BOUND_SESSION_ID
(2): RESERVE' w/ MSG_ID
(3): RESERVE w/ BOUND_MSG_ID and BOUND_SESSION_ID
Figure 8: Sender-initiated Reservation for Both End-to-end and Tunnel
Signaling
The first possibility is shown in the example messaging flow of
Figure 8, where the tunnel RESERVE' message (2), aka the triggering
message in QoS NSLP message binding terms, arrives first. Since the
message binding is bidirectional, Texit records the MSG_ID of the
RESERVE' message (2), enques it and starts a MsgIDWait timer waiting
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for the end-to-end RESERVE message (3), aka the bound signaling
message in QoS NSLP message binding terms. The timer value is set to
the default retransmission timeout period QOSNSLP_REQUEST_RETRY.
When the end-to-end RESERVE message (3) arrives, Texit notices that
there is an existing stored MSG_ID which matches the MSG_ID in the
BOUND_MSG_ID object of the incoming RESERVE message (3). Therefore
the message binding condition has been satisfied. Texit resumes
processing of the tunnel RESERVE' message (2), creates the
reservation state for the tunnel session, and sends a tunnel
RESPONSE' message (4) to Tentry. At the same time, Texit checks the
BOUND_SESSION_ID object of the end-to-end RESERVE message (3) and
records the binding of the corresponding tunnel session with the end-
to-end session. Texit also updates the end-to-end RESERVE message
based on the result of the tunnel session reservation, removes its
tunnel BOUND_SESSION_ID and BOUND_MSG_ID object and forwards the end-
to-end RESERVE message (5) along the path towards the receiver. When
the receiver receives the end-to-end RESERVE message (5), it sends an
end-to-end RESPONSE message (6) back to the sender.
The second possibility is that the end-to-end RESERVE message arrives
before the tunnel RESERVE' message at Texit. In that case, Texit
notices a BOUND_SESSION_ID object and a BOUND_MSG_ID object in the
end-to-end RESERVE message, but realizes that the tunnel session does
not exist yet. So Texit enques the RESERVE message and starts a
MsgIDWait timer. The timer value is set to the default
retransmission timeout period QOSNSLP_REQUEST_RETRY. When the
corresponding tunnel RESERVE' message arrives with a MSG_ID matching
that of the outstanding BOUND_MSG_ID object, the message binding
condition is satisfied. Texit sends a tunnel RESPONSE' message back
to Tentry and updates the end-to-end RESERVE message by incorporating
the result of the tunnel session reservation, as well as removing the
tunnel BOUND_SESSION_ID and BOUND_MSG_ID objects. Texit then
forwards the end-to-end RESERVE message along the path towards the
receiver. When the receiver receives the end-to-end RESERVE message,
it sends an end-to-end RESPONSE message back to the sender.
Yet another possibility is that the tunnel RESERVE' message arrives
at Texit first but the end-to-end RESERVE message never arrives. In
that case, the MsgIDWait timer for the queued tunnel RESERVE' message
will expire. Texit should send a tunnel RESPONSE' message back to
Tentry indicating a reservation error has occurred, and discard the
tunnel RESERVE' message. The last possibility is that the end-to-end
RESERVE message arrives at Texit first but the tunnel RESERVE'
message never arrives. And in that case, the MsgIDWait timer for the
queued end-to-end RESERVE message will expire. Texit should treat
this situation as a local reservation failure, and according to
[I-D.ietf-nsis-qos-nslp], Texit as a stateful QoS NSLP should
generate an end-to-end RESPONSE message indicating the RESERVE error
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to the sender.
Once the end-to-end and the tunnel QoS session have both been
successfully created and associated, the tunnel end-points Tentry and
Texit coordinate the signaling between the two sessions and make sure
that adjustment or teardown of either session may trigger similar
actions for the other session as necessary, by invoking appropriate
signaling messages.
6.2. Receiver-initiated Reservation
Figure 9 shows the typical messaging sequence of how NSIS signaling
operates over IP tunnels when both end-to-end and tunnel sessions are
receiver-initiated. Upon receiving an end-to-end QUERY message (1)
from the sender, Tentry chooses the tunnel Flow ID and sends a tunnel
QUERY' message (2) matching the request of the end-to-end session
towards Texit. This tunnel QUERY' message (2) is meant to discover
QoS characteristics of the tunnel path, rather than initiating an
actual reservation. Therefore, it includes a Request Identification
Information (RII) object but does not set the RESERVE-INIT flag. The
tunnel QUERY' message (2) is processed hop-by-hop inside the tunnel
for the flow identified by the tunnel Flow ID. When Texit receives
this tunnel QUERY' message (2), it replies with a corresponding
tunnel RESPONSE' message (3) containing the tunnel path
characteristics. After receiving the tunnel RESPONSE' message (3),
Tentry creates the tunnel session, generates an outgoing end-to-end
QUERY message (4) considering the tunnel path characteristics,
appends a tunnel BOUND_SESSION_ID object containing the tunnel
Session ID, and sends it toward Texit using normal tunnel
encapsulation. The end-to-end QUERY message (4) passes along tunnel
intermediate nodes like other tunneled packets. Upon receiving this
end-to-end QUERY message (4), Texit notices the tunnel session
binding and creates the tunnel session state, removes the tunnel
BOUND_SESSION_ID object and forwards the end-to-end QUERY message (5)
further along the path.
The end-to-end QUERY message (5) arrives at the receiver and triggers
a RESERVE message (6). When Texit receives the RESERVE message (6),
it notices that the session is bound to a receiver-initiated tunnel
session. Therefore, Texit triggers a RESERVE' message (7) toward
Tentry for the tunnel session reservation. This tunnel RESERVE'
message (7) includes a randomly generated 128-bit MSG_ID. Meanwhile,
Texit inserts a BOUND_MSG_ID object containing the same MSG_ID and a
BOUND_SESSION_ID object containing the tunnel Session ID into the
end-to-end RESERVE message (8), and sends it towards Tentry using
normal tunnel encapsulation. The Message_Binding_Type flag of the
MSG_ID and BOUND_MSG_ID objects in the RESERVE' and RESERVE messages
(7,8) is SET, indicating a bidirectional binding.
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Sender Tentry Tmid Texit Receiver
| | | | |
| QUERY(1) | | | |
+------------->| | | |
| | QUERY'(2) | | |
| +=============>| | |
| | | QUERY'(2) | |
| | +=============>| |
| | | RESPONSE'(3) | |
| | |<=============+ |
| | RESPONSE'(3) | | |
| |<=============+ | |
| | QUERY(4) | |
| +---------------------------->| |
| | | | QUERY(5) |
| | | +------------->|
| | | | RESERVE(6) |
| | | |<-------------+
| | | RESERVE'(7) | |
| | |<=============+ |
| | RESERVE'(7) | | |
| |<=============+ | |
| | RESERVE(8) | |
| |<----------------------------+ |
| | RESPONSE'(9) | | |
| +=============>| | |
| | | RESPONSE'(9) | |
| | +=============>| |
| RESERVE(10) | | | |
|<-------------+ | | |
| RESPONSE(11) | | | |
+------------->| | | |
| | RESPONSE(11) | |
| +---------------------------->| |
| | | | RESPONSE(11) |
| | | +------------->|
| | | | |
| | | | |
(1,5): QUERY w/ RESERVE-INIT (2): QUERY' w/ RII
(4): QUERY w/ RESERVE-INIT and BOUND_SESSION_ID
(6,10): RESERVE w/o BOUND_SESSION_ID (7): RESERVE' w/ MSG_ID
(8): RESERVE w/ BOUND_MSG_ID and BOUND_SESSION_ID
Figure 9: Receiver-initiated Reservation for Both End-to-end and
Tunnel Signaling
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At Tentry, the tunnel RESERVE' message (7) and the end-to-end RESERVE
message (8) could arrive in different orders. In a typical case
shown in Figure 9, the tunnel RESERVE' message (7) arrives first.
Tentry records the MSG_ID of the tunnel RESERVE' message (7) and
starts a MsgIDWait timer. When the end-to-end RESERVE message (8)
with the BOUND_MSG_ID object containing the same MSG_ID arrives, the
message binding condition is satisfied. Tentry resumes processing of
the tunnel RESERVE' message (7), creates the reservation state for
the tunnel session, and sends a tunnel RESPONSE' message (9) to
Texit. At the same time, Tentry creates the outgoing end-to-end
RESERVE message (10) by incorporating results of the tunnel session
reservation and removing the BOUND_SESSION_ID and BOUND_MSG_ID
objects, and forwards it along the path towards the sender. When the
sender receives the end-to-end RESERVE message (10), it sends an end-
to-end RESPONSE message (11) back to the receiver.
If the end-to-end RESERVE message arrives before the tunnel RESERVE'
message at Tentry, or either of the two messages fails to arrive at
Tentry, the processing rules at Tentry is similar to those of Texit
in the same situation discussed in Section 6.1.
Once the end-to-end and the tunnel QoS session have both been
successfully created and associated, the tunnel end-points Tentry and
Texit coordinate the signaling between the two sessions and make sure
that adjustment or teardown of either session can trigger similar
actions for the other session as necessary, by invoking appropriate
signaling messages.
7. NSIS-Tunnel Signaling Capability Discovery
The mechanism of NSIS operating over IP tunnels requires the
coordination of both tunnel end-points in tasks such as special
encapsulation and decapsulation of data flow packets according to the
chosen tunnel Flow ID, as well as the possible creation and
adjustment of the end-to-end and tunnel QoS sessions. Therefore, one
NSIS-tunnel-aware end-point needs to know that the other tunnel end-
point is also NSIS-tunnel-aware before initiating this NSIS operating
over IP tunnel mechanism. In some cases, especially for IP tunnels
with pre-configured QoS sessions, an NSIS-tunnel-aware end-point can
learn about whether the other tunnel end-point is also NSIS-tunnel-
aware through pre-configuration. In other cases where such pre-
configuration is not available, the initiating NSIS-tunnel-aware end-
point may dynamically discover the other tunnel end-point's
capability through a QoS NSLP NODE_CAPABILITY object defined in this
section.
7.1. NODE_CAPABILITY Object Format
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The NODE_CAPABILITY object contains a standard NSLP object header
followed by the object value, as shown in Figure 10.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|B|r|r| Type |r|r|r|r| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: NODE_CAPABILITY Object Format
Type: (TBD by IANA)
Length: 1, measured in units of 32-bit word
Value: a single 'T' bit indicating the node supports the NSIS-tunnel
handling mechanisms defined in this document. The reserved bits in
the value field can be used to signal other node characteristics in
the future.
The bits marked 'A' and 'B' define the desired behavior for objects
whose Type field is not recognized. If a node does not recognize the
NODE_CAPABILITY object, the desired behavior is "Ignore". That is,
the object must be deleted and the rest of the message processed as
usual. This can be satisfied by setting 'AB' to '01'.
7.2. Using NODE_CAPABILITY Object
The NODE_CAPABILITY object is included in a QUERY or RESERVE message
by a tunnel end-point that needs to learn about the other end-point's
NSIS tunnel handling capability. If the receiving tunnel end-point
is indeed NSIS-tunnel-aware, it recognizes this object and knows that
the sending end-point is NSIS-tunnel-aware. The receiving tunnel
end-point places the same object in a RESPONSE message to inform the
sending end-point that it is also NSIS-tunnel-aware. The use of the
NODE_CAPABILITY object in the cases of sender-initiated reservation
and receiver-initiated reservation are further detailed below.
First, assume that the end-to-end session is sender-initiated and an
NSIS-tunnel-aware Tentry wants to discover the NSIS-tunnel capability
of Texit (e.g., in Figure 8). After receiving the first end-to-end
RESERVE message and without initiating a tunnel RESERVE' message,
Tentry inserts an RII object and a NODE_CAPABILITY object with T bit
set into the end-to-end RESERVE message and sends it to Texit. When
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Texit receives this RESERVE message, if it is also NSIS-tunnel-aware,
it learns that Tentry is NSIS-tunnel-aware and includes the same
object with T bit set in the following end-to-end RESPONSE message
sent back to Tentry. Otherwise, Texit ignores and deletes the
NODE_CAPABILITY object. When Tentry receives the RESPONSE message,
it knows whether Texit is NSIS-tunnel-aware by checking the T bit in
the NODE_CAPABILITY object.
Second, assume that the end-to-end session is receiver-initiated and
the NSIS-tunnel-aware Tentry wants to discover the NSIS-tunnel
capability of Texit (e.g., in Figure 9). Upon receiving the first
end-to-end QUERY message and without initiating a tunnel QUERY'
message, Tentry includes an RII object and a NODE_CAPABILITY object
with T bit set in the end-to-end QUERY message and sends it toward
Texit. If Texit is NSIS-tunnel-aware, it learns from the
NODE_CAPABILITY object that Tentry is also NSIS-tunnel-aware and
includes the same object with T bit in the later end-to-end RESERVE
message sent to Tentry. Otherwise, Texit ignores and deletes the
NODE_CAPABILITY object. When Tentry receives the end-to-end RESERVE
message, it knows whether Texit is NSIS-tunnel-aware by checking the
T bit in the NODE_CAPABILITY object.
8. IANA Considerations
This document defines a new object type called NODE_CAPABILITY for
QoS NSLP. Its Type value needs to be assigned by IANA. The object
format and the setting of the extensibility bits are defined in
Section 7.
9. Security Considerations
This draft does not raise new security threats. Security
considerations for NSIS NTLP and QoS NSLP are discussed in
[I-D.ietf-nsis-ntlp] and [I-D.ietf-nsis-qos-nslp], respectively.
General threats for NSIS can be found in [RFC4081].
10. Acknowledgements
The authors would like to thank Roland Bless, Hannes Tschofenig,
Georgios Karagiannis and other members of the NSIS working group for
comments to this work.
11. References
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11.1. Normative References
[I-D.ietf-nsis-ntlp]
Schulzrinne, H. and M. Stiemerling, "GIST: General
Internet Signalling Transport", draft-ietf-nsis-ntlp-20
(work in progress), June 2009.
[I-D.ietf-nsis-qos-nslp]
Manner, J., Karagiannis, G., and A. McDonald, "NSLP for
Quality-of-Service Signaling", draft-ietf-nsis-qos-nslp-18
(work in progress), January 2010.
11.2. Informative References
[I-D.ietf-nsis-applicability-mobility-signaling]
Sanda, T., Fu, X., Jeong, S., Manner, J., and H.
Tschofenig, "Applicability Statement of NSIS Protocols in
Mobile Environments",
draft-ietf-nsis-applicability-mobility-signaling-14 (work
in progress), January 2010.
[I-D.ietf-nsis-nslp-natfw]
Stiemerling, M., Tschofenig, H., Aoun, C., and E. Davies,
"NAT/Firewall NSIS Signaling Layer Protocol (NSLP)",
draft-ietf-nsis-nslp-natfw-23 (work in progress),
February 2010.
[I-D.ietf-nsis-qspec]
Bader, A., Kappler, C., and D. Oran, "QoS NSLP QSPEC
Template", draft-ietf-nsis-qspec-24 (work in progress),
January 2010.
[RFC1701] Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
Routing Encapsulation (GRE)", RFC 1701, October 1994.
[RFC1702] Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
Routing Encapsulation over IPv4 networks", RFC 1702,
October 1994.
[RFC1853] Simpson, W., "IP in IP Tunneling", RFC 1853, October 1995.
[RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
October 1996.
[RFC2004] Perkins, C., "Minimal Encapsulation within IP", RFC 2004,
October 1996.
[RFC2113] Katz, D., "IP Router Alert Option", RFC 2113,
Shen, et al. Expires August 19, 2010 [Page 25]
Internet-Draft NSIS Operation over IP Tunnels February 2010
February 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2207] Berger, L. and T. O'Malley, "RSVP Extensions for IPSEC
Data Flows", RFC 2207, September 1997.
[RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, December 1998.
[RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option",
RFC 2711, October 1999.
[RFC2746] Terzis, A., Krawczyk, J., Wroclawski, J., and L. Zhang,
"RSVP Operation Over IP Tunnels", RFC 2746, January 2000.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
March 2000.
[RFC3220] Perkins, C., "IP Mobility Support for IPv4", RFC 3220,
January 2002.
[RFC3697] Rajahalme, J., Conta, A., Carpenter, B., and S. Deering,
"IPv6 Flow Label Specification", RFC 3697, March 2004.
[RFC4080] Hancock, R., Karagiannis, G., Loughney, J., and S. Van den
Bosch, "Next Steps in Signaling (NSIS): Framework",
RFC 4080, June 2005.
[RFC4081] Tschofenig, H. and D. Kroeselberg, "Security Threats for
Next Steps in Signaling (NSIS)", RFC 4081, June 2005.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213, October 2005.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
Shen, et al. Expires August 19, 2010 [Page 26]
Internet-Draft NSIS Operation over IP Tunnels February 2010
Authors' Addresses
Charles Shen
Columbia University
Department of Computer Science
1214 Amsterdam Avenue, MC 0401
New York, NY 10027
USA
Phone: +1 212 854 3109
Email: charles@cs.columbia.edu
Henning Schulzrinne
Columbia University
Department of Computer Science
1214 Amsterdam Avenue, MC 0401
New York, NY 10027
USA
Phone: +1 212 939 7004
Email: hgs@cs.columbia.edu
Sung-Hyuck Lee
SAMSUNG Advanced Institute of Technology
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9552
Email: starsu.lee@samsung.com
Jong Ho Bang
SAMSUNG Advanced Institute of Technology
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9585
Email: jh0278.bang@samsung.com
Shen, et al. Expires August 19, 2010 [Page 27]
