TEAS Working Group M. Taillon
Internet-Draft T. Saad, Ed.
Intended Status: Standards Track R. Gandhi, Ed.
Expires: December 5, 2016 Z. Ali
Cisco Systems
June 3, 2016
Extensions to Resource Reservation Protocol For Fast Reroute of
Traffic Engineering GMPLS LSPs
draft-ietf-teas-gmpls-lsp-fastreroute-05
Abstract
This document defines Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) signaling extensions to support Fast Reroute
(FRR) of Packet Switched Capable (PSC) Generalized Multi-Protocol
Label Switching (GMPLS) Label Switched Paths (LSPs). These signaling
extensions allow the coordination of a bidirectional bypass tunnel
assignment protecting a common facility in both forward and reverse
directions of a co-routed bidirectional LSP. In addition, these
extensions enable the re-direction of bidirectional traffic and
signaling onto bypass tunnels that ensure co-routedness of data and
signaling paths in the forward and reverse directions after FRR to
avoid RSVP soft-state timeout.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 4
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
3. Fast Reroute For Unidirectional GMPLS LSPs . . . . . . . . . . 5
4. Bypass Tunnel Assignment for Bidirectional GMPLS LSPs . . . . 5
4.1. Bidirectional GMPLS Bypass Tunnel Direction . . . . . . . 5
4.2. Merge Point Labels . . . . . . . . . . . . . . . . . . . . 5
4.3. Merge Point Addresses . . . . . . . . . . . . . . . . . . 6
4.4. RRO IPv4/IPv6 Subobject Flags . . . . . . . . . . . . . . 6
4.5. Bidirectional Bypass Tunnel Assignment Co-ordination . . . 6
4.5.1. Bidirectional Bypass Tunnel Assignment Signaling
Procedure . . . . . . . . . . . . . . . . . . . . . . 7
4.5.2. Bidirectional Bypass Tunnel Assignment Policy . . . . 8
4.5.3. BYPASS_ASSIGNMENT Subobject . . . . . . . . . . . . . 9
5. Link Protection Bypass Tunnels for Bidirectional GMPLS LSPs . 10
5.1. Behavior After Link Failure After FRR . . . . . . . . . . 10
5.2. Revertive Behavior After Link Failure After FRR . . . . . 11
6. Node Protection Bypass Tunnels for Bidirectional GMPLS LSPs . 11
6.1. Behavior After FRR and Link Failure . . . . . . . . . . . 11
6.2. Behavior After Link Failure To Re-coroute . . . . . . . . 12
6.3. Revertive Behavior After Link Failure . . . . . . . . . . 13
7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.1. Normative References . . . . . . . . . . . . . . . . . . 15
10.2. Informative References . . . . . . . . . . . . . . . . . 15
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 16
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
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Packet Switched Capable (PSC) Traffic Engineering (TE) tunnels are
signaled using Generalized Multi-Protocol Label Switching (GMPLS)
signaling procedures specified in [RFC3473] for both unidirectional
and bidirectional LSPs. Fast Reroute (FRR) [RFC4090] has been widely
deployed in the packet TE networks today and is desirable for TE
GMPLS LSPs. Using FRR methods also allows the leveraging of existing
mechanisms for failure detection and restoration in deployed
networks.
The FRR procedures defined in [RFC4090] describe the behavior of the
Point of Local Repair (PLR) to reroute traffic and signaling onto the
bypass tunnel in the event of a failure for unidirectional LSPs.
These procedures are applicable to unidirectional protected LSPs
signaled using either RSVP-TE [RFC3209] or GMPLS procedures
[RFC3473], but they do not address issues that arise when employing
FRR for bidirectional co-routed GMPLS Label Switched Paths (LSPs).
When bidirectional bypass tunnels are used to locally protect
bidirectional co-routed GMPLS LSPs, the upstream and downstream PLRs
may independently assign different bidirectional bypass tunnels in
the forward and reverse directions. There is no mechanism in the FRR
procedures defined in [RFC4090] to coordinate the bidirectional
bypass tunnel selection between the downstream and upstream PLRs.
When using FRR procedures with bidirectional co-routed GMPLS LSPs, it
is possible in some cases for the RSVP signaling refreshes to stop
reaching some nodes along the primary LSP path after the PLRs finish
rerouting signaling onto the bypass tunnels. This may occur when
using node protection bypass tunnels after a link failure event and
when RSVP signaling is sent in-fiber and in-band with data. This is
caused by the asymmetry of paths that may be taken by the
bidirectional LSP's signaling in the forward and reverse directions
after FRR reroute. In such cases, the RSVP soft-state timeout
causes the protected bidirectional LSP to be destroyed, with
subsequent traffic loss after FRR.
Protection State Coordination Protocol [RFC6378] is applicable to FRR
[RFC4090] for local protection of bidirectional co-routed LSPs in
order to minimize traffic disruptions in both directions. However,
this does not address the above mentioned problem of RSVP soft-state
timeout in control plane.
This document proposes solutions to the above mentioned problems by
providing mechanisms in the control plane to complement the FRR
procedures of [RFC4090] in order to maintain the RSVP soft-state for
bidirectional co-routed protected GMPLS LSPs and achieve symmetry in
the paths followed by the traffic and signaling in the forward and
reverse directions after FRR. The document further extends RSVP
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signaling so that the bidirectional bypass tunnel selected by the
upstream PLR matches the one selected by the downstream PLR node for
a bidirectional co-routed LSP.
Procedures defined in this document apply to co-routed GMPLS signaled
PSC bidirectional TE primary and FRR bypass LSPs. Unless otherwise
specified in this document, the FRR procedures defined in [RFC4090]
are not modified by this document.
2. Conventions Used in This Document
2.1. Key Word Definitions
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 RFC 2119 [RFC2119].
2.2. Terminology
The reader is assumed to be familiar with the terminology in
[RFC2205] and [RFC3209].
LSR: An MPLS Label-Switch Router.
LSP: An MPLS Label-Switched Path.
Local Repair: Techniques used to repair LSP tunnels quickly when a
node or link along the LSP's path fails.
PLR: Point of Local Repair. The head-end LSR of a bypass tunnel or a
detour LSP.
PSC: Packet Switched Capable.
Protected LSP: An LSP is said to be protected at a given hop if it
has one or multiple associated bypass tunnels originating at that
hop.
Bypass Tunnel: An LSP that is used to protect a set of LSPs passing
over a common facility.
NHOP Bypass Tunnel: Next-Hop Bypass Tunnel. A bypass tunnel that
bypasses a single link of the protected LSP.
NNHOP Bypass Tunnel: Next-Next-Hop Bypass Tunnel. A bypass tunnel
that bypasses a single node of the protected LSP.
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MP: Merge Point. The LSR where one or more bypass tunnels rejoin the
path of the protected LSP downstream of the potential failure. The
same LSR may be both an MP and a PLR simultaneously.
Downstream PLR: A PLR that locally detects a fault and reroutes
traffic in the same direction of the protected bidirectional LSP RSVP
Path signaling. A downstream PLR has a corresponding downstream MP.
Upstream PLR: A PLR that locally detects a fault and reroutes traffic
in the opposite direction of the protected bidirectional LSP RSVP
Path signaling. An upstream PLR has a corresponding upstream MP.
Point of Remote Repair (PRR): An upstream PLR that triggers reroute
of traffic and signaling based on procedures described in this
document.
3. Fast Reroute For Unidirectional GMPLS LSPs
The FRR procedures defined in [RFC4090] are applicable to
unidirectional protected LSPs signaled using either RSVP-TE or GMPLS
procedures and are not modified by the extensions defined in this
document. These FRR procedures also apply to bidirectional
associated GMPLS LSPs where two unidirectional GMPLS LSPs are bound
together by using association signaling [RFC7551].
4. Bypass Tunnel Assignment for Bidirectional GMPLS LSPs
This section describes signaling procedures for bidirectional bypass
tunnel assignment for GMPLS signaled PSC bidirectional co-routed TE
LSPs.
4.1. Bidirectional GMPLS Bypass Tunnel Direction
This document defines procedures where GMPLS bypass tunnels are
provisioned in the same direction as the GMPLS primary LSPs. In
other words, the GMPLS bypass tunnels originate on the downstream PLR
and terminate on the downstream MP. As the originating downstream
PLR node has the policy information about the locally provisioned
bypass tunnels, it always initiates the bypass tunnel assignment.
The GMPLS bypass tunnels originating from the upstream PLR and
terminating on the upstream MP are outside the scope of this
document.
4.2. Merge Point Labels
To correctly reroute data traffic over a node protection bypass
tunnel, the downstream and upstream PLRs have to know, in advance,
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the downstream and upstream MP labels so that data in the forward and
reverse directions can be redirected through the bypass tunnel after
FRR respectively.
[RFC4090] defines procedures for the downstream PLR to obtain the
protected LSP's downstream MP label from recorded labels in the RRO
of the RSVP Resv message received at the downstream PLR.
To obtain the upstream MP label, the procedures specified in
[RFC4090] are used to record the upstream MP label in the RRO of the
RSVP Path message. The upstream PLR obtains the upstream MP label
from the recorded labels in the RRO of the received RSVP Path
message.
4.3. Merge Point Addresses
To correctly assign a bidirectional bypass tunnel, the downstream and
upstream PLRs have to know, in advance, the downstream and upstream
MP addresses.
[RFC4561] defines procedures for the downstream PLR to obtain the
protected LSP's downstream MP address from the recorded node-IDs in
the RRO of the RSVP Resv message received at the downstream PLR.
To obtain the upstream MP address, the procedures specified in
[RFC4561] are used to record upstream MP node-ID in the RRO of the
RSVP Path message. The upstream PLR obtains the upstream MP address
from the recorded node-IDs in the RRO of the received RSVP Path
message.
4.4. RRO IPv4/IPv6 Subobject Flags
RRO IPv4/IPv6 subobject flags are defined in [RFC4090], Section 4.4
and are equally applicable to the FRR procedure for bidirectional
GMPLS LSPs.
The procedures defined in [RFC4090] are used by the downstream PLR to
signal the IPv4/IPv6 subobject flags upstream in the RRO of the RSVP
Resv message. Similarly, these procedures are used by the downstream
PLR to signal the IPv4/IPv6 subobject flags downstream in the RRO of
the RSVP Path message.
4.5. Bidirectional Bypass Tunnel Assignment Co-ordination
This document defines signaling procedures and a new
BYPASS_ASSIGNMENT subobject in the RSVP RECORD_ROUTE Object used to
co-ordinate the bidirectional bypass tunnel assignment between the
downstream and upstream PLRs.
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4.5.1. Bidirectional Bypass Tunnel Assignment Signaling Procedure
It is desirable to coordinate the bidirectional bypass tunnel
selected at the downstream and upstream PLRs so that rerouted traffic
and signaling flow on co-routed paths after FRR. To achieve this, a
new RSVP subobject is defined for RECORD_ROUTE Object (RRO) that
identifies a bidirectional bypass tunnel that is assigned at a
downstream PLR to protect a bidirectional LSP.
The BYPASS_ASSIGNMENT subobject SHOULD be added by each downstream
PLR in the RSVP Path RECORD_ROUTE message of the GMPLS signaled
bidirectional primary LSP to record the downstream bidirectional
bypass tunnel assignment. This subobject is sent in the RSVP Path
RECORD_ROUTE message every time the downstream PLR assigns or updates
the bypass tunnel assignment. The upstream PLR (downstream MP)
simply reflects the bypass tunnel assignment in the reverse
direction.
When the BYPASS_ASSIGNMENT subobject is added in the RECORD_ROUTE
Object:
o The BYPASS_ASSIGNMENT subobject MUST be added prior to the
Node-ID subobject containing the node's address.
o The Node-ID subobject MUST also be added.
o The IPv4 or IPv6 subobject MUST also be added.
o The Label subobject MUST also be added.
In the absence of BYPASS_ASSIGNMENT subobject, the upstream PLR
(downstream MP) SHOULD NOT assign a bypass tunnel in the reverse
direction. This allows the downstream PLR to always initiate the
bypass assignment and upstream PLR (downstream MP) to simply reflect
the bypass assignment.
The upstream PLR (downstream MP) that detects a BYPASS_ASSIGNMENT
subobject, selects a reverse bypass tunnel that terminates locally
with the matching tunnel-ID and has a source address matching the
node-ID sub-object received in the subobject. The RRO containing
BYPASS_ASSIGNMENT subobject(s) is then simply forwarded downstream in
the RSVP Path message.
An upstream PLR (downstream MP) SHOULD examine the entire Path RRO
and look at all BYPASS_ASSIGNMENT subobjects in order to assign a
reverse bypass tunnel. The choice of a reverse bypass tunnel (if
multiple bypass tunnels exist) is based on the local policy on the
downstream MP and is discussed in Section 4.5.2 of this document.
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The bypass assignment co-ordination procedure described in this
Section can be used for both one-to-one backup described in Section
3.1 of [RFC4090] and facility backup described in Section 3.2 of
[RFC4090].
4.5.2. Bidirectional Bypass Tunnel Assignment Policy
In the case of upstream PLR receiving multiple BYPASS_ASSIGNMENT
subobjects from multiple downstream PLRs, the selection of a bypass
tunnel in the reverse direction can be based on local policy.
Examples of such a policy could be to prefer link protection over
node protection, or to prefer the bypass tunnel to the furthest
upstream node. When different policies are used for bypass tunnel
assignment on the LSP path, it may result in some links in the
reverse direction not assigned bypass protection during LSP setup as
shown in examples below.
As shown in Example 1, node A assigns a node protection bypass tunnel
in the forward direction but node C does not reflect the node
protection bypass tunnel in the reverse direction for a protected
bidirectional GMPLS LSP A-B-C. Both nodes B and C assign a link
protection bypass tunnel. As a result, there is no fast reroute
protection available in the reverse direction for link A-B for this
LSP during the LSP setup. Note that this is corrected by node C
during the re-coroute procedure after the FRR failure on link A-B as
specified in Section 6 of this document since GMPLS bypass tunnels
are bidirectional.
+------->>------+
/ +->>-+ \
/ / \ \
/ / \ \
A --->>--- B --->>---- C
-> PATH \ /
\ /
+-<<-+
Example 1: An example of different bypass assignment policy
As shown in Example 2, nodes A and C assign a node protection bypass
tunnel for a protected bidirectional GMPLS LSP A-B-C. Node B assigns
a link protection bypass tunnel but node C does not reflect the
reverse link protection bypass tunnel. As a result, there is no fast
reroute protection available in the reverse direction for link A-B
for this LSP during the LSP setup. Note that this is corrected by
node C during the re-coroute procedure after the FRR failure on link
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A-B as specified in Section 6 of this document since GMPLS bypass
tunnels are bidirectional.
+------>>------+
/ +->>-+ \
/ / \ \
/ / \ \
A --->>--- B --->>---- C
\ -> PATH /
\ /
\ /
+------<<-------+
Example 2: An example of different bypass assignment policy
4.5.3. BYPASS_ASSIGNMENT Subobject
The BYPASS_ASSIGNMENT subobject is used to inform the downstream MP
of the bypass tunnel being assigned by the PLR. This can be used to
coordinate the bypass tunnel assignment for the protected LSP by the
downstream and upstream PLRs in the forward and reverse directions
respectively prior or after the failure occurrence.
This subobject SHOULD be inserted into the Path RRO by the downstream
PLR. It SHOULD NOT be inserted into an RRO by a node which is not a
downstream PLR. It MUST NOT be changed by downstream LSRs and MUST
NOT be added to a Resv RRO.
The BYPASS_ASSIGNMENT subobject in RRO 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Bypass Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
Downstream Bypass Assignment. Value is TBA by IANA.
Length
The Length contains the total length of the subobject in
bytes, including the Type and Length fields. The length is
always 4 bytes.
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Bypass Tunnel ID
The bypass tunnel identifier (16 bits).
5. Link Protection Bypass Tunnels for Bidirectional GMPLS LSPs
When a bidirectional link protection bypass tunnel is used, after a
link failure, the downstream PLR reroutes traffic and RSVP messages
over the bypass tunnel using the procedures defined in [RFC4090].
Upstream PLR reroutes traffic upon detecting the link failure or upon
receiving RSVP Path message over a bidirectional bypass tunnel.
Upstream PLR reroutes RSVP Resv signaling upon receiving RSVP Path
message over a bidirectional bypass tunnel. This allows both traffic
and RSVP signaling to flow on symmetric paths in the forward and
reverse directions of a bidirectional LSP.
<- RESV
[R1]---[R2]----[R3]------x-----[R4]----[R5]
-> PATH \ /
+<<--------->>+
T3
-> PATH
RESV <-
Protected LSP: {R1-R2-R3-R4-R5}
R3's Bypass T3: {R3-R4}
Figure 1: Flow of RSVP signaling after FRR and link failure
Consider the Traffic Engineered (TE) network shown in Figure 1.
Assume every link in the network is protected with a link protection
bypass tunnel (e.g. bypass tunnel T3). For the protected
bidirectional co-routed LSP whose head-end is on node R1 and tail-end
is on node R5, each traversed node (a potential PLR) assigns a link
protection bidirectional co-routed bypass tunnel.
5.1. Behavior After Link Failure After FRR
Consider a link R3-R4 on the protected LSP path fails. The
downstream PLR R3 and upstream PLR R4 independently trigger fast
reroute procedures to redirect traffic onto bypass tunnels T3 in the
forward and reverse directions. The downstream PLR R3 also reroutes
RSVP Path state onto the bypass tunnel T3 using procedures described
in [RFC4090]. The upstream PLR R4 reroutes RSVP Resv onto the
reverse bypass tunnel T3 upon receiving RSVP Path message over bypass
tunnel T3.
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5.2. Revertive Behavior After Link Failure After FRR
Revertive behavior as defined in [RFC4090], Section 6.5.2, is
applicable to the link protection of GMPLS bidirectional LSPs. When
using the local revertive mode, when downstream MP receives Path
messages over the restored path, it starts sending Resv over the
restored path and stops sending Resv over the reverse bypass tunnel.
No additional procedure other than that specified in [RFC4090] is
introduced for revertive behavior by this document.
6. Node Protection Bypass Tunnels for Bidirectional GMPLS LSPs
T1
+<<--------->>+
/ \ <- RESV
[R1]---[R2]----[R3]--x--[R4]----[R5]---[R6]
-> PATH \ /
+<<---------->>+
T2
Protected LSP: {R1-R2-R3-R4-R5-R6}
R3's Bypass T2: {R3-R5}
R4's Bypass T1: {R4-R2}
Figure 2: Flow of RSVP signaling after FRR and link failure
Consider the Traffic Engineered (TE) network shown in Figure 2.
Assume every link in the network is protected with a node protection
bypass tunnel. For the protected bidirectional co-routed LSP whose
head-end is on node R1 and tail-end is on node R6, each traversed
node (a potential PLR) assigns a node protection bidirectional co-
routed bypass tunnel.
The proposed solution introduces two phases to invoking FRR
procedures by the PLR after the link failure. The first phase
comprises of FRR procedures to fast reroute data traffic onto bypass
tunnels in the forward and reverse directions. The second phase
re-coroutes the data and signaling in the forward and reverse
directions after the first phase.
6.1. Behavior After FRR and Link Failure
Consider a link R3-R4 on the protected LSP path fails. The
downstream PLR R3 and upstream PLR R4 independently trigger fast
reroute procedures to redirect traffic onto respective bypass tunnels
T2 and T1 in the forward and reverse directions. The downstream PLR
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R3 also reroutes RSVP Path state onto the bypass tunnel T2 using
procedures described in [RFC4090]. Note, at this point, node R4
stops receiving RSVP Path refreshes for the protected bidirectional
LSP while primary protected traffic continues to flow over bypass
tunnels.
6.2. Behavior After Link Failure To Re-coroute
The downstream MP R5 that receives rerouted protected LSP RSVP Path
message through the bypass tunnel, in addition to the regular MP
processing defined in [RFC4090], gets promoted to a Point of Remote
Repair (PRR) role and performs the following actions to re-coroute
signaling and data traffic over the same path in both directions:
o Finds the bypass tunnel in the reverse direction that terminates
on the downstream PLR R3. Note: the downstream PLR R3's address
can be extracted from the "IPV4 tunnel sender address" in the
SENDER_TEMPLATE Object of the primary LSP (see [RFC4090], Section
6.1.1).
o If reverse bypass tunnel is found and the primary LSP traffic is
not already rerouted over the found bypass tunnel T2, the PRR R5
activates FRR reroute procedures to direct traffic over the found
bypass tunnel T2 in the reverse direction. In addition, the PRR
R5 also reroutes RSVP Resv over the bypass tunnel T2 in the
reverse direction.
o If reverse bypass tunnel is not found, the PRR R5 immediately
tears down the primary LSP.
<- RESV
[R1]---[R2]----[R3]--X--[R4]----[R5]---[R6]
PATH -> \ /
+<<-------->>+
Bypass Tunnel T2
traffic + signaling
Protected LSP: {R1-R2-R3-R4-R5-R6}
R3's Bypass T2: {R3-R5}
Figure 3: Flow of RSVP signaling after FRR and re-corouted
Figure 3 describes the path taken by the traffic and signaling after
completing re-coroute of data and signaling in the forward and
reverse paths described earlier. Node R4 will stop receiving the
Path and Resv messages and it will timeout the RSVP soft-state,
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however, this will not cause the LSP to be torn down. RSVP signaling
at node R2 is not affected by the FRR and re-corouting.
If the link failure is unidirectional in the direction of R4 to R3,
node R3 will stop receiving the RSVP Resv messages from node R4 and
this will cause RSVP soft-state to timeout on node R3. However,
unidirectional link failure in the opposite direction will not result
in RSVP soft-state timeout as node R5 will trigger the re-coroute
procedure after receiving RSVP Path message over the bypass tunnel
from node R3.
If downstream MP R5 receives multiple RSVP Path messages through
multiple bypass tunnels (e.g. as a result of multiple failures), the
PRR SHOULD identify a bypass tunnel that terminates on the farthest
downstream PLR along the protected LSP path (closest to the primary
bidirectional LSP head-end) and activate the reroute procedures
mentioned above.
The downstream MP MAY optionally support re-corouting in data plane
as follows. If the downstream MP is pre-configured with
bidirectional bypass tunnel, as soon as the MP node receives the
primary LSP packets on this bypass tunnel, it MAY switch the upstream
traffic on to this bypass tunnel. In order to identify the primary
LSP packets through this bypass tunnel, Penultimate Hop Popping (PHP)
of the bypass tunnel MUST be disabled. The signaling procedure
described above in this Section will still apply, and MP checks
whether the primary LSP traffic and signaling is already rerouted
over the found bypass tunnel, if not, perform the above signaling
procedure.
6.3. Revertive Behavior After Link Failure
Revertive behavior as defined in [RFC4090], Section 6.5.2, is
applicable to node protection of GMPLS bidirectional LSPs. When
using the local revertive mode, when downstream MP (R4) (before
re-corouting) and PRR (R5) (after re-corouting) receive Path messages
over the restored path, they start sending Resv over the restored
path and stop sending Resv over the reverse bypass tunnel. No
additional procedure other than that specified in [RFC4090] is
introduced for revertive behavior by this document.
7. Compatibility
New RSVP subobject BYPASS_ASSIGNMENT is defined for RECORD_ROUTE
Object in this document. Per [RFC2205], nodes not supporting this
subobject will ignore the subobject but forward it without
modification.
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8. Security Considerations
This document introduces a new BYPASS_ASSIGNMENT subobject for the
RECORD_ROUTE Object that is carried in an RSVP signaling message.
Thus in the event of the interception of a signaling message, more
information about LSP's fast reroute protection can be deduced than
was previously the case. This is judged to be a very minor security
risk as this information is already available by other means.
Otherwise, this document introduces no additional security
considerations. For general discussion on MPLS and GMPLS related
security issues, see the MPLS/GMPLS security framework [RFC5920].
9. IANA Considerations
IANA manages the "RSVP PARAMETERS" registry located at
<http://www.iana.org/assignments/rsvp-parameters>. IANA is requested
to assign a value for the new BYPASS_ASSIGNMENT subobject in the
"Class Type 21 ROUTE_RECORD - Type 1 Route Record" registry.
This document introduces a new subobject for RECORD_ROUTE Object:
+--------+-------------------+---------+---------+---------------+
| Value | Description | Carried | Carried | Reference |
| | | in Path | in Resv | |
+--------+-------------------+---------+---------+---------------+
| TBA By | BYPASS_ASSIGNMENT | Yes | No | This document |
| IANA | subobject | | | |
+--------+-------------------+---------+---------+---------------+
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
January 2003.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
[RFC4561] Vasseur, J.P., Ed., Ali, Z., and S. Sivabalan, "Definition
of a Record Route Object (RRO) Node-Id Sub-Object", RFC
4561, June 2006.
[RFC7551] Zhang, F., Ed., Jing, R., and Gandhi, R., Ed., "RSVP-TE
Extensions for Associated Bidirectional LSPs", RFC 7551,
May 2015.
10.2. Informative References
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
[RFC6378] Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and
A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear
Protection", RFC 6378, October 2011.
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Acknowledgements
Authors would like to thank George Swallow for his detailed and
useful comments and suggestions. Authors would also like to thank
Nobo Akiya, Loa Andersson, Matt Hartley and Gregory Mirsky for
reviewing this document.
Contributors
Frederic Jounay
Orange CH
EMail: frederic.jounay@orange.ch
Manav Bhatia Ionos Networks Banglore India
EMail: manav@ionosnetworks.com
Lizhong Jin Shanghai, China
EMail: lizho.jin@gmail.com
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Authors' Addresses
Mike Taillon
Cisco Systems, Inc.
EMail: mtaillon@cisco.com
Tarek Saad (editor)
Cisco Systems, Inc.
EMail: tsaad@cisco.com
Rakesh Gandhi (editor)
Cisco Systems, Inc.
EMail: rgandhi@cisco.com
Zafar Ali
Cisco Systems, Inc.
EMail: zali@cisco.com
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