draft-ietf-teas-gmpls-lsp-fastreroute-05.txt   draft-ietf-teas-gmpls-lsp-fastreroute-06.txt 
TEAS Working Group M. Taillon TEAS Working Group M. Taillon
Internet-Draft T. Saad, Ed. Internet-Draft T. Saad, Ed.
Intended Status: Standards Track R. Gandhi, Ed. Intended Status: Standards Track R. Gandhi, Ed.
Expires: December 5, 2016 Z. Ali Expires: April 4, 2017 Z. Ali
Cisco Systems Cisco Systems
June 3, 2016 October 1, 2016
Extensions to Resource Reservation Protocol For Fast Reroute of Extensions to Resource Reservation Protocol For Fast Reroute of
Traffic Engineering GMPLS LSPs Traffic Engineering GMPLS LSPs
draft-ietf-teas-gmpls-lsp-fastreroute-05 draft-ietf-teas-gmpls-lsp-fastreroute-06
Abstract Abstract
This document defines Resource Reservation Protocol - Traffic This document defines Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) signaling extensions to support Fast Reroute Engineering (RSVP-TE) signaling extensions to support Fast Reroute
(FRR) of Packet Switched Capable (PSC) Generalized Multi-Protocol (FRR) of Packet Switched Capable (PSC) Generalized Multi-Protocol
Label Switching (GMPLS) Label Switched Paths (LSPs). These signaling Label Switching (GMPLS) Label Switched Paths (LSPs). These signaling
extensions allow the coordination of a bidirectional bypass tunnel extensions allow the coordination of a bidirectional bypass tunnel
assignment protecting a common facility in both forward and reverse assignment protecting a common facility in both forward and reverse
directions of a co-routed bidirectional LSP. In addition, these directions of a co-routed bidirectional LSP. In addition, these
skipping to change at page 2, line 17 skipping to change at page 2, line 14
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4 2. Conventions Used in This Document . . . . . . . . . . . . . . 4
2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 4 2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 4
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Acronyms and Abbreviations . . . . . . . . . . . . . . . . 5
3. Fast Reroute For Unidirectional GMPLS LSPs . . . . . . . . . . 5 3. Fast Reroute For Unidirectional GMPLS LSPs . . . . . . . . . . 5
4. Bypass Tunnel Assignment for Bidirectional GMPLS LSPs . . . . 5 4. Fast Reroute for Bidirectional GMPLS LSPs . . . . . . . . . . 5
4.1. Bidirectional GMPLS Bypass Tunnel Direction . . . . . . . 5 4.1. Bidirectional GMPLS Bypass Tunnel Direction . . . . . . . 5
4.2. Merge Point Labels . . . . . . . . . . . . . . . . . . . . 5 4.2. Merge Point Labels . . . . . . . . . . . . . . . . . . . . 6
4.3. Merge Point Addresses . . . . . . . . . . . . . . . . . . 6 4.3. Merge Point Addresses . . . . . . . . . . . . . . . . . . 6
4.4. RRO IPv4/IPv6 Subobject Flags . . . . . . . . . . . . . . 6 4.4. RRO IPv4/IPv6 Subobject Flags . . . . . . . . . . . . . . 6
4.5. Bidirectional Bypass Tunnel Assignment Co-ordination . . . 6 4.5. Bidirectional Bypass Tunnel Assignment Co-ordination . . . 7
4.5.1. Bidirectional Bypass Tunnel Assignment Signaling 4.5.1. Bidirectional Bypass Tunnel Assignment Signaling
Procedure . . . . . . . . . . . . . . . . . . . . . . 7 Procedure . . . . . . . . . . . . . . . . . . . . . . 7
4.5.2. Bidirectional Bypass Tunnel Assignment Policy . . . . 8 4.5.2. Multiple Bidirectional Bypass Tunnel Assignments . . . 8
4.5.3. BYPASS_ASSIGNMENT Subobject . . . . . . . . . . . . . 9 4.6. Fast Reroute Procedure After Link Failure . . . . . . . . 9
5. Link Protection Bypass Tunnels for Bidirectional GMPLS LSPs . 10 5. Link Protection for Bidirectional GMPLS LSPs . . . . . . . . . 10
5.1. Behavior After Link Failure After FRR . . . . . . . . . . 10 5.1. Behavior After Link Failure . . . . . . . . . . . . . . . 10
5.2. Revertive Behavior After Link Failure After FRR . . . . . 11 5.2. Revertive Behavior After Fast Reroute . . . . . . . . . . 11
6. Node Protection Bypass Tunnels for Bidirectional GMPLS LSPs . 11 6. Node Protection for Bidirectional GMPLS LSPs . . . . . . . . . 11
6.1. Behavior After FRR and Link Failure . . . . . . . . . . . 11 6.1. Behavior After Link Failure . . . . . . . . . . . . . . . 12
6.2. Behavior After Link Failure To Re-coroute . . . . . . . . 12 6.2. Behavior After Link Failure To Re-coroute . . . . . . . . 12
6.3. Revertive Behavior After Link Failure . . . . . . . . . . 13 6.3. Revertive Behavior After Fast Reroute . . . . . . . . . . 13
7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 13 7. Unidirectional Link Failures . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. Message and Object Definitions . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8.1. BYPASS_ASSIGNMENT Subobject . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.2. FRR Bypass Assignment Error Notify Message . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 15 9. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . 15 10. Security Considerations . . . . . . . . . . . . . . . . . . . 16
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 16 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 11.1. BYPASS_ASSIGNMENT Subobject . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 11.2. FRR Bypass Assignment Error Notify Message . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
12.1. Normative References . . . . . . . . . . . . . . . . . . 18
12.2. Informative References . . . . . . . . . . . . . . . . . 18
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 19
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
Packet Switched Capable (PSC) Traffic Engineering (TE) tunnels are
signaled using Generalized Multi-Protocol Label Switching (GMPLS) Packet Switched Capable (PSC) Traffic Engineering (TE) tunnels can be
setup using Generalized Multi-Protocol Label Switching (GMPLS)
signaling procedures specified in [RFC3473] for both unidirectional signaling procedures specified in [RFC3473] for both unidirectional
and bidirectional LSPs. Fast Reroute (FRR) [RFC4090] has been widely and bidirectional LSPs. Fast Reroute (FRR) [RFC4090] has been widely
deployed in the packet TE networks today and is desirable for TE deployed in the packet TE networks today and is desirable for TE
GMPLS LSPs. Using FRR methods also allows the leveraging of existing GMPLS LSPs. Using FRR methods also allows the leveraging of the
mechanisms for failure detection and restoration in deployed existing mechanisms for failure detection and restoration in deployed
networks. networks.
The FRR procedures defined in [RFC4090] describe the behavior of the The FRR procedures defined in [RFC4090] describe the behavior of the
Point of Local Repair (PLR) to reroute traffic and signaling onto the Point of Local Repair (PLR) to reroute traffic and signaling onto the
bypass tunnel in the event of a failure for unidirectional LSPs. bypass tunnel in the event of a failure for protected LSPs. Those
These procedures are applicable to unidirectional protected LSPs procedures are applicable to the unidirectional protected LSPs
signaled using either RSVP-TE [RFC3209] or GMPLS procedures signaled using either RSVP-TE [RFC3209] or GMPLS procedures
[RFC3473], but they do not address issues that arise when employing [RFC3473]. When using the FRR procedures defined in [RFC4090] with
FRR for bidirectional co-routed GMPLS Label Switched Paths (LSPs). co-routed bidirectional GMPLS LSPs, it is desired that same PLR and
Merge Point (MP) pairs are selected in each direction and both PLR
When bidirectional bypass tunnels are used to locally protect and MP assign the same bidirectional bypass tunnel. This document
bidirectional co-routed GMPLS LSPs, the upstream and downstream PLRs extends the FRR procedures defined in [RFC4090] to coordinate the
may independently assign different bidirectional bypass tunnels in bidirectional bypass tunnel assignment and to exchange MP labels
the forward and reverse directions. There is no mechanism in the FRR between upstream and downstream PLRs of the protected co-routed
procedures defined in [RFC4090] to coordinate the bidirectional bidirectional LSP.
bypass tunnel selection between the downstream and upstream PLRs.
When using FRR procedures with bidirectional co-routed GMPLS LSPs, it When using FRR procedures with co-routed bidirectional GMPLS LSPs, it
is possible in some cases for the RSVP signaling refreshes to stop is possible in some cases for the RSVP signaling refreshes to stop
reaching some nodes along the primary LSP path after the PLRs finish reaching certain nodes along the protected LSP path after the PLRs
rerouting signaling onto the bypass tunnels. This may occur when finish rerouting signaling onto the bypass tunnels. This can occur
using node protection bypass tunnels after a link failure event and after a failure event when using node protection bypass tunnels and
when RSVP signaling is sent in-fiber and in-band with data. This is when RSVP signaling is sent in-band with data. As shown in Figure 2,
this is possible even with selecting the same bidirectional bypass
tunnels in both directions and the same PLR and MP pairs. This is
caused by the asymmetry of paths that may be taken by the caused by the asymmetry of paths that may be taken by the
bidirectional LSP's signaling in the forward and reverse directions bidirectional LSP's signaling in the forward and reverse directions
after FRR reroute. In such cases, the RSVP soft-state timeout due to upstream and downstream PLRs independently triggering FRR. In
causes the protected bidirectional LSP to be destroyed, with such cases, after FRR, the RSVP soft-state timeout causes the
subsequent traffic loss after FRR. protected bidirectional LSP to be torn down, with subsequent traffic
loss.
Protection State Coordination Protocol [RFC6378] is applicable to FRR Protection State Coordination Protocol [RFC6378] is applicable to FRR
[RFC4090] for local protection of bidirectional co-routed LSPs in [RFC4090] for local protection of co-routed bidirectional LSPs in
order to minimize traffic disruptions in both directions. However, order to minimize traffic disruptions in both directions. However,
this does not address the above mentioned problem of RSVP soft-state this does not address the above mentioned problem of RSVP soft-state
timeout in control plane. timeout in control plane.
This document proposes solutions to the above mentioned problems by This document proposes a solution to the RSVP soft-state timeout
providing mechanisms in the control plane to complement the FRR issue by providing mechanisms in the control plane to complement the
procedures of [RFC4090] in order to maintain the RSVP soft-state for FRR procedures of [RFC4090]. The proposal allows to maintain the
bidirectional co-routed protected GMPLS LSPs and achieve symmetry in RSVP soft-state for co-routed bidirectional protected GMPLS LSPs and
the paths followed by the traffic and signaling in the forward and achieve co-routedness of the paths followed by the traffic and
reverse directions after FRR. The document further extends RSVP signaling in the forward and reverse directions after FRR.
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 Procedures defined in this document apply to GMPLS signaled PSC TE
PSC bidirectional TE primary and FRR bypass LSPs. Unless otherwise co-routed bidirectional protected LSPs and FRR co-routed
specified in this document, the FRR procedures defined in [RFC4090] bidirectional bypass tunnels. Unless otherwise specified in this
are not modified by this document. document, the FRR procedures defined in [RFC4090] are not modified by
this document. FRR mechanism for associated bidirectional GMPLS LSPs
where two unidirectional GMPLS LSPs are bound together by using
association signaling [RFC7551] is outside the scope of this
document.
2. Conventions Used in This Document 2. Conventions Used in This Document
2.1. Key Word Definitions 2.1. Key Word Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2.2. Terminology 2.2. Terminology
The reader is assumed to be familiar with the terminology in The reader is assumed to be familiar with the terminology in
[RFC2205] and [RFC3209]. [RFC2205], [RFC3209], [RFC3471], [RFC3473] and [RFC4090].
LSR: An MPLS Label-Switch Router. Downstream PLR: Downstream Point of Local Repair. The PLR that
locally detects a failure in the downstream direction of the traffic
flow and reroutes traffic in the same direction of the protected
bidirectional LSP RSVP Path signaling. A downstream PLR has a
corresponding downstream MP.
LSP: An MPLS Label-Switched Path. Downstream MP: Downstream Merge Point. The LSR where one or more
backup tunnels rejoin the path of the protected LSP in the downstream
direction of the traffic flow. The same LSR may be both a downstream
MP and an upstream PLR simultaneously.
Local Repair: Techniques used to repair LSP tunnels quickly when a Upstream PLR: Upstream Point of Local Repair. The PLR that locally
node or link along the LSP's path fails. detects a failure in the upstream direction of the traffic flow and
reroutes traffic in the opposite direction of the protected
bidirectional LSP RSVP Path signaling. An upstream PLR has a
corresponding upstream MP.
PLR: Point of Local Repair. The head-end LSR of a bypass tunnel or a Upstream MP: Upstream Merge Point. The LSR where one or more backup
detour LSP. tunnels rejoin the path of the protected LSP in the upstream
direction of the traffic flow. The same LSR may be both an upstream
MP and a downstream PLR simultaneously.
PSC: Packet Switched Capable. Point of Remote Repair (PRR): A downstream MP that assumes the role
of upstream PLR upon receiving protected LSP's Path message over the
bypass tunnel and triggers reroute of traffic and signaling in the
upstream direction of the traffic flow using the procedures described
in this document.
Protected LSP: An LSP is said to be protected at a given hop if it 2.3. Acronyms and Abbreviations
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 GMPLS: Generalized Multi-Protocol Label Switching
over a common facility.
NHOP Bypass Tunnel: Next-Hop Bypass Tunnel. A bypass tunnel that LSP: An MPLS Label Switched Path
bypasses a single link of the protected LSP.
NNHOP Bypass Tunnel: Next-Next-Hop Bypass Tunnel. A bypass tunnel LSR: An MPLS Label Switching Router
that bypasses a single node of the protected LSP.
MP: Merge Point. The LSR where one or more bypass tunnels rejoin the MP: Merge Point
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 MPLS: Multi-Protocol Label Switching
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 PLR: Point of Local Repair
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 PSC: Packet Switched Capable
of traffic and signaling based on procedures described in this
document. RSVP: Resource ReSerVation Protocol
TE: Traffic Engineering
3. Fast Reroute For Unidirectional GMPLS LSPs 3. Fast Reroute For Unidirectional GMPLS LSPs
The FRR procedures defined in [RFC4090] are applicable to The FRR procedures defined in [RFC4090] are applicable to
unidirectional protected LSPs signaled using either RSVP-TE or GMPLS unidirectional protected LSPs signaled using either RSVP-TE or GMPLS
procedures and are not modified by the extensions defined in this procedures and are not modified by the extensions defined in this
document. These FRR procedures also apply to bidirectional document.
associated GMPLS LSPs where two unidirectional GMPLS LSPs are bound
together by using association signaling [RFC7551].
4. Bypass Tunnel Assignment for Bidirectional GMPLS LSPs 4. Fast Reroute for Bidirectional GMPLS LSPs
This section describes signaling procedures for bidirectional bypass This section describes signaling procedures for FRR bidirectional
tunnel assignment for GMPLS signaled PSC bidirectional co-routed TE bypass tunnel assignment for GMPLS signaled PSC co-routed
LSPs. bidirectional TE LSPs.
4.1. Bidirectional GMPLS Bypass Tunnel Direction 4.1. Bidirectional GMPLS Bypass Tunnel Direction
This document defines procedures where GMPLS bypass tunnels are This document defines procedures where bidirectional GMPLS bypass
provisioned in the same direction as the GMPLS primary LSPs. In tunnels are signaled in the same direction as the protected GMPLS
other words, the GMPLS bypass tunnels originate on the downstream PLR LSPs. In other words, the bidirectional GMPLS bypass tunnels
and terminate on the downstream MP. As the originating downstream originate on the downstream PLR and terminate on the downstream MP.
PLR node has the policy information about the locally provisioned As the originating downstream PLR has the policy information about
bypass tunnels, it always initiates the bypass tunnel assignment. the locally provisioned bypass tunnels, it always initiates the
The GMPLS bypass tunnels originating from the upstream PLR and bypass tunnel assignment. The bidirectional GMPLS bypass tunnels
terminating on the upstream MP are outside the scope of this originating from the upstream PLR and terminating on the upstream MP
document. are outside the scope of this document.
4.2. Merge Point Labels 4.2. Merge Point Labels
To correctly reroute data traffic over a node protection bypass To correctly reroute data traffic over a node protection bypass
tunnel, the downstream and upstream PLRs have to know, in advance, tunnel, the downstream and upstream PLRs have to know, in advance,
the downstream and upstream MP labels so that data in the forward and the downstream and upstream MP labels of the protected LSP so that
reverse directions can be redirected through the bypass tunnel after data in the forward and reverse directions can be redirected through
FRR respectively. the bypass tunnel after FRR respectively.
[RFC4090] defines procedures for the downstream PLR to obtain the [RFC4090] defines procedures for the downstream PLR to obtain the
protected LSP's downstream MP label from recorded labels in the RRO protected LSP's downstream MP label from recorded labels in the
of the RSVP Resv message received at the downstream PLR. RECORD_ROUTE Object (RRO) of the RSVP Resv message received at the
downstream PLR.
To obtain the upstream MP label, the procedures specified in To obtain the upstream MP label, the procedures specified in
[RFC4090] are used to record the upstream MP label in the RRO of the [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 RSVP Path message of the protected LSP. The upstream PLR obtains the
from the recorded labels in the RRO of the received RSVP Path upstream MP label from the recorded labels in the RRO of the received
message. RSVP Path message.
4.3. Merge Point Addresses 4.3. Merge Point Addresses
To correctly assign a bidirectional bypass tunnel, the downstream and To correctly assign a bidirectional bypass tunnel, the downstream and
upstream PLRs have to know, in advance, the downstream and upstream upstream PLRs have to know, in advance, the downstream and upstream
MP addresses. MP addresses.
[RFC4561] defines procedures for the downstream PLR to obtain the [RFC4561] defines procedures for the downstream PLR to obtain the
protected LSP's downstream MP address from the recorded node-IDs in protected LSP's downstream MP address from the recorded Node-IDs in
the RRO of the RSVP Resv message received at the downstream PLR. the RRO of the RSVP Resv message received at the downstream PLR.
To obtain the upstream MP address, the procedures specified in To obtain the upstream MP address, the procedures specified in
[RFC4561] are used to record upstream MP node-ID in the RRO of the [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 RSVP Path message of the protected LSP. The upstream PLR obtains the
from the recorded node-IDs in the RRO of the received RSVP Path upstream MP address from the recorded Node-IDs in the RRO of the
message. received RSVP Path message.
4.4. RRO IPv4/IPv6 Subobject Flags 4.4. RRO IPv4/IPv6 Subobject Flags
RRO IPv4/IPv6 subobject flags are defined in [RFC4090], Section 4.4 RRO IPv4/IPv6 subobject flags are defined in [RFC4090], Section 4.4
and are equally applicable to the FRR procedure for bidirectional and are equally applicable to the FRR procedure for bidirectional
GMPLS LSPs. GMPLS LSPs.
The procedures defined in [RFC4090] are used by the downstream PLR to 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 signal the IPv4/IPv6 subobject flags upstream in the RRO of the RSVP
Resv message. Similarly, these procedures are used by the downstream Resv message of the protected LSP. Similarly, those procedures are
PLR to signal the IPv4/IPv6 subobject flags downstream in the RRO of used by the downstream PLR to signal the IPv4/IPv6 subobject flags
the RSVP Path message. downstream in the RRO of the RSVP Path message of the protected LSP.
4.5. Bidirectional Bypass Tunnel Assignment Co-ordination 4.5. Bidirectional Bypass Tunnel Assignment Co-ordination
This document defines signaling procedures and a new This document defines signaling procedures and a new
BYPASS_ASSIGNMENT subobject in the RSVP RECORD_ROUTE Object used to BYPASS_ASSIGNMENT subobject in the RSVP RECORD_ROUTE Object (RRO)
co-ordinate the bidirectional bypass tunnel assignment between the used to co-ordinate the bidirectional bypass tunnel assignment
downstream and upstream PLRs. between the downstream and upstream PLRs.
4.5.1. Bidirectional Bypass Tunnel Assignment Signaling Procedure 4.5.1. Bidirectional Bypass Tunnel Assignment Signaling Procedure
It is desirable to coordinate the bidirectional bypass tunnel It is desirable to coordinate the bidirectional bypass tunnel
selected at the downstream and upstream PLRs so that rerouted traffic selected at the downstream and upstream PLRs so that rerouted traffic
and signaling flow on co-routed paths after FRR. To achieve this, a and signaling flow on co-routed paths after FRR. To achieve this, a
new RSVP subobject is defined for RECORD_ROUTE Object (RRO) that new RSVP subobject is defined for RRO that identifies a bidirectional
identifies a bidirectional bypass tunnel that is assigned at a bypass tunnel that is assigned at a downstream PLR to protect a
downstream PLR to protect a bidirectional LSP. 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 When the procedures defined in this document are in use, the
Object: BYPASS_ASSIGNMENT subobject MUST be added by each downstream PLR in
the RSVP Path RRO message of the GMPLS signaled bidirectional
protected LSP to record the downstream bidirectional bypass tunnel
assignment. This subobject is sent in the RSVP Path RRO message
every time the downstream PLR assigns or updates the bypass tunnel
assignment. The downstream PLR can assign a bypass tunnel when
processing the first Path message of the protected LSP, however, it
can not update the forwarding plane until it receives the Resv
message containing the downstream MP label.
o The BYPASS_ASSIGNMENT subobject MUST be added prior to the The upstream PLR (downstream MP) simply reflects the bypass tunnel
Node-ID subobject containing the node's address. assignment in the reverse direction. The absence of
BYPASS_ASSIGNMENT subobject in RRO means that the relevant node or
interface is not protected by a bidirectional bypass tunnel. Hence,
the upstream PLR need not assign a bypass tunnel in the reverse
direction.
o The Node-ID subobject MUST also be added. When the BYPASS_ASSIGNMENT subobject is added in the RRO:
o The IPv4 or IPv6 subobject MUST also be added. o The IPv4 or IPv6 subobject containing Node-ID address MUST also be
added [RFC4561]. The Node-ID address must match the source
address of the bypass tunnel selected for this protected LSP.
o The Label subobject MUST also be added. o The BYPASS_ASSIGNMENT subobject MUST be added immediately after
the Node-ID address.
In the absence of BYPASS_ASSIGNMENT subobject, the upstream PLR o The Label subobject MUST also be added [RFC3209].
(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 The rules for adding an IPv4 or IPv6 Interface address subobject and
subobject, selects a reverse bypass tunnel that terminates locally Unnumbered Interface ID subobject as specified in [RFC3209] and
with the matching tunnel-ID and has a source address matching the [RFC4090] are not modified by the above procedure. The options
node-ID sub-object received in the subobject. The RRO containing specified in Section 6.1.3 in [RFC4990] are also applicable as long
BYPASS_ASSIGNMENT subobject(s) is then simply forwarded downstream in as above mentioned rules are followed when using the FRR procedures
the RSVP Path message. defined in this document.
An upstream PLR (downstream MP) SHOULD examine the entire Path RRO An upstream PLR (downstream MP) SHOULD check all BYPASS_ASSIGNMENT
and look at all BYPASS_ASSIGNMENT subobjects in order to assign a subobjects in the Path RRO in order to assign a reverse bypass
reverse bypass tunnel. The choice of a reverse bypass tunnel (if tunnel. The upstream PLR that detects a BYPASS_ASSIGNMENT subobject,
multiple bypass tunnels exist) is based on the local policy on the selects a reverse bypass tunnel that terminates locally with the
downstream MP and is discussed in Section 4.5.2 of this document. destination address and tunnel-ID from the subobject, and has a
source address matching the Node-ID address. The RRO may contain
multiple addresses to identify a node, however, the upstream PLR
relies on the Node-ID address preceding the BYPASS_ASSIGNMENT
subobject for identifying the bypass tunnel. If the bypass tunnel is
not found, the upstream PLR SHOULD send a Notify message [RFC3473]
with Error-code - FRR Bypass Assignment Error (value: TBA1) and Sub-
code - Bypass Tunnel Not Found (value: TBA3) to the downstream PLR.
The RRO containing BYPASS_ASSIGNMENT subobject(s) is then simply
forwarded downstream in the RSVP Path message.
The bypass assignment co-ordination procedure described in this The bypass assignment co-ordination procedure described in this
Section can be used for both one-to-one backup described in Section Section can be used for both facility backup described in Section 3.2
3.1 of [RFC4090] and facility backup described in Section 3.2 of of [RFC4090] and one-to-one backup described in Section 3.1 of
[RFC4090]. [RFC4090]. As specified in [RFC4090], Section 4.2, the DETOUR_OBJECT
can be used in one-to-one backup method to identify detour LSPs. In
4.5.2. Bidirectional Bypass Tunnel Assignment Policy one-to-one backup method, if the bypass tunnel is already in-use at
the upstream PLR, it SHOULD send a Notify message [RFC3473] with
In the case of upstream PLR receiving multiple BYPASS_ASSIGNMENT Error-code - FRR Bypass Assignment Error (value: TBA1) and Sub-code -
subobjects from multiple downstream PLRs, the selection of a bypass One-to-one Bypass Already In-use (value: TBA4) to the downstream
tunnel in the reverse direction can be based on local policy. PLR.
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
A-B as specified in Section 6 of this document since GMPLS bypass
tunnels are bidirectional.
+------>>------+ 4.5.2. Multiple Bidirectional Bypass Tunnel Assignments
/ +->>-+ \
/ / \ \
/ / \ \
A --->>--- B --->>---- C
\ -> PATH /
\ /
\ /
+------<<-------+
Example 2: An example of different bypass assignment policy The upstream PLR may receive multiple bypass tunnel assignments for a
protected LSP from different downstream PLRs. The choice of a
reverse bypass tunnel is based on the local policy on the upstream
PLR. 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.
4.5.3. BYPASS_ASSIGNMENT Subobject As shown in Example 1 and Example 2, for the protected bidirectional
GMPLS LSP R4-R5-R6, the upstream PLR R6 receives multiple bypass
tunnel assignments, one from downstream PLR R4 for node protection
and one from downstream PLR R5 for link protection. In Example 1, R6
prefers the link protection bypass tunnel from downstream PLR R5
whereas in Example 2, R6 prefers the node protection bypass tunnel
from downstream PLR R4.
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. [R4]--->>---[R5]--->>---[R6]
PATH -> \ /
\ /
+-<<--+
This subobject SHOULD be inserted into the Path RRO by the downstream Example 1: Link protection is preferred on downstream MP
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: +------->>--------+
/ +->>--+ \
/ / \ \
/ / \ \
[R4]--->>---[R5]--->>---[R6]
\ PATH -> /
\ /
\ /
+-------<<--------+
0 1 2 3 Example 2: Node protection is preferred on downstream MP
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 In both examples above, the upstream PLR SHOULD send a Notify message
[RFC3473] with Error-code - FRR Bypass Assignment Error (value: TBA1)
and Sub-code - Bypass Assignment Cannot Be Used (value: TBA2) to the
downstream PLR to indicate that it cannot use the bypass tunnel
assignment. The upstream PLR can then remove the bypass assignment
and select an alternate bypass tunnel.
Downstream Bypass Assignment. Value is TBA by IANA. If multiple bypass tunnel assignments are present on the upstream PLR
R6 at the time of a failure, any resulted asymmetry gets corrected
using the re-coroute procedure after FRR as specified in Section 6.2
of this document.
Length 4.6. Fast Reroute Procedure After Link Failure
When a bidirectional bypass tunnel is used, after a link failure,
following procedure is followed:
The Length contains the total length of the subobject in o The downstream PLR reroutes traffic and RSVP Path signaling over
bytes, including the Type and Length fields. The length is the bidirectional bypass tunnel using the procedures defined in
always 4 bytes. [RFC4090].
Bypass Tunnel ID o Upstream PLR reroutes traffic upon detecting the link failure or
upon receiving RSVP Path message over the bidirectional bypass
tunnel.
The bypass tunnel identifier (16 bits). o Upstream PLR also reroutes RSVP Resv signaling after receiving
RSVP Path message over the bidirectional bypass tunnel.
5. Link Protection Bypass Tunnels for Bidirectional GMPLS LSPs This procedure allows both traffic and RSVP signaling to flow on
symmetric paths in the forward and reverse directions of a protected
bidirectional GMPLS LSP. This is described in Section 5 for link
protection bypass tunnels and Section 6 for node protection bypass
tunnels.
When a bidirectional link protection bypass tunnel is used, after a 5. Link Protection for Bidirectional GMPLS LSPs
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 <- RESV
[R1]---[R2]----[R3]------x-----[R4]----[R5] [R1]----[R2]----[R3]-----x-----[R4]----[R5]----[R6]
-> PATH \ / PATH -> \ /
+<<--------->>+ \ /
T3 +<<----->>+
-> PATH T3
RESV <- PATH ->
<- RESV
Protected LSP: {R1-R2-R3-R4-R5} Protected LSP: {R1-R2-R3-R4-R5-R6}
R3's Bypass T3: {R3-R4} R3's Bypass T3: {R3-R4}
Figure 1: Flow of RSVP signaling after FRR and link failure Figure 1: Flow of RSVP signaling after link failure and FRR
Consider the Traffic Engineered (TE) network shown in Figure 1. Consider the TE network shown in Figure 1. Assume every link in the
Assume every link in the network is protected with a link protection network is protected with a link protection bypass tunnel (e.g.
bypass tunnel (e.g. bypass tunnel T3). For the protected bypass tunnel T3). For the protected co-routed bidirectional LSP
bidirectional co-routed LSP whose head-end is on node R1 and tail-end whose head-end is on node R1 and tail-end is on node R6, each
is on node R5, each traversed node (a potential PLR) assigns a link traversed node (a potential PLR) assigns a link protection co-routed
protection bidirectional co-routed bypass tunnel. bidirectional bypass tunnel.
5.1. Behavior After Link Failure After FRR 5.1. Behavior After Link Failure
Consider a link R3-R4 on the protected LSP path fails. The Consider the link R3-R4 on the protected LSP path fails. The
downstream PLR R3 and upstream PLR R4 independently trigger fast downstream PLR R3 and upstream PLR R4 independently trigger fast
reroute procedures to redirect traffic onto bypass tunnels T3 in the reroute to redirect traffic onto bypass tunnels T3 in the forward and
forward and reverse directions. The downstream PLR R3 also reroutes reverse directions. The downstream PLR R3 also reroutes RSVP Path
RSVP Path state onto the bypass tunnel T3 using procedures described messages onto the bypass tunnel T3 using the procedures described in
in [RFC4090]. The upstream PLR R4 reroutes RSVP Resv onto the [RFC4090]. The upstream PLR R4 reroutes RSVP Resv messages onto the
reverse bypass tunnel T3 upon receiving RSVP Path message over bypass reverse bypass tunnel T3 upon receiving RSVP Path message over bypass
tunnel T3. tunnel T3.
5.2. Revertive Behavior After Link Failure After FRR 5.2. Revertive Behavior After Fast Reroute
Revertive behavior as defined in [RFC4090], Section 6.5.2, is Revertive behavior as defined in [RFC4090], Section 6.5.2, is
applicable to the link protection of GMPLS bidirectional LSPs. When applicable to the link protection of bidirectional GMPLS LSPs. When
using the local revertive mode, when downstream MP receives Path using the local revertive mode, after the link R3-R4 is restored,
messages over the restored path, it starts sending Resv over the following node behaviors apply:
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 o The downstream PLR R3 starts sending the Path messages and traffic
flow of the protected LSP over the restored link and stops sending
them over the bypass tunnel.
T1 o The upstream PLR R4 starts sending the Resv messages and traffic
+<<--------->>+ flow of the protected LSP over the restored link and stops sending
them over the bypass tunnel.
o When upstream PLR R4 receives the protected LSP Path messages over
the restored link, if not already done, it starts sending Resv
messages and traffic flow of the protected LSP over the restored
link and stops sending them over the bypass tunnel.
6. Node Protection for Bidirectional GMPLS LSPs
T1
+<<------->>+
/ \
/ \ <- RESV / \ <- RESV
[R1]---[R2]----[R3]--x--[R4]----[R5]---[R6] [R1]----[R2]----[R3]--x--[R4]----[R5]----[R6]
-> PATH \ / PATH -> \ /
+<<---------->>+ \ /
T2 +<<------->>+
T2
Protected LSP: {R1-R2-R3-R4-R5-R6} Protected LSP: {R1-R2-R3-R4-R5-R6}
R3's Bypass T2: {R3-R5} R3's Bypass T2: {R3-R5}
R4's Bypass T1: {R4-R2} R4's Bypass T1: {R4-R2}
Figure 2: Flow of RSVP signaling after FRR and link failure Figure 2: Flow of RSVP signaling after link failure and FRR
Consider the Traffic Engineered (TE) network shown in Figure 2. Consider the TE network shown in Figure 2. Assume every link in the
Assume every link in the network is protected with a node protection network is protected with a node protection bypass tunnel. For the
bypass tunnel. For the protected bidirectional co-routed LSP whose protected co-routed bidirectional LSP whose head-end is on node R1
head-end is on node R1 and tail-end is on node R6, each traversed and tail-end is on node R6, each traversed node (a potential PLR)
node (a potential PLR) assigns a node protection bidirectional co- assigns a node protection co-routed bidirectional bypass tunnel.
routed bypass tunnel.
The proposed solution introduces two phases to invoking FRR The proposed solution introduces two phases to invoking FRR
procedures by the PLR after the link failure. The first phase procedures by the PLR after the link failure. The first phase
comprises of FRR procedures to fast reroute data traffic onto bypass comprises of FRR procedures to fast reroute data traffic onto bypass
tunnels in the forward and reverse directions. The second phase tunnels in the forward and reverse directions. The second phase
re-coroutes the data and signaling in the forward and reverse re-coroutes the data and signaling in the forward and reverse
directions after the first phase. directions after the first phase.
6.1. Behavior After FRR and Link Failure 6.1. Behavior After Link Failure
Consider a link R3-R4 on the protected LSP path fails. The Consider a link R3-R4 on the protected LSP path fails. The
downstream PLR R3 and upstream PLR R4 independently trigger fast downstream PLR R3 and upstream PLR R4 independently trigger fast
reroute procedures to redirect traffic onto respective bypass tunnels reroute procedures to redirect traffic onto respective bypass tunnels
T2 and T1 in the forward and reverse directions. The downstream PLR T2 and T1 in the forward and reverse directions. The downstream PLR
R3 also reroutes RSVP Path state onto the bypass tunnel T2 using R3 also reroutes RSVP Path messages over the bypass tunnel T2 using
procedures described in [RFC4090]. Note, at this point, node R4 the procedures described in [RFC4090]. Note, at this point, node R4
stops receiving RSVP Path refreshes for the protected bidirectional stops receiving RSVP Path refreshes for the protected bidirectional
LSP while primary protected traffic continues to flow over bypass LSP while protected traffic continues to flow over bypass tunnels.
tunnels. As node R4 does not receive Path messages over the bypass tunnel, it
does not reroute RSVP Resv messages over the reverse bypass tunnel.
6.2. Behavior After Link Failure To Re-coroute 6.2. Behavior After Link Failure To Re-coroute
The downstream MP R5 that receives rerouted protected LSP RSVP Path The downstream MP R5 that receives rerouted protected LSP RSVP Path
message through the bypass tunnel, in addition to the regular MP message through the bypass tunnel, in addition to the regular MP
processing defined in [RFC4090], gets promoted to a Point of Remote processing defined in [RFC4090], gets promoted to a Point of Remote
Repair (PRR) role and performs the following actions to re-coroute Repair (PRR) role and performs the following actions to re-coroute
signaling and data traffic over the same path in both directions: signaling and data traffic over the same path in the reverse
direction:
o Finds the bypass tunnel in the reverse direction that terminates o Finds the bypass tunnel in the reverse direction that terminates
on the downstream PLR R3. Note: the downstream PLR R3's address on the downstream PLR R3. Note: the downstream PLR R3's address
can be extracted from the "IPV4 tunnel sender address" in the can be extracted from the "IPV4 tunnel sender address" in the
SENDER_TEMPLATE Object of the primary LSP (see [RFC4090], Section SENDER_TEMPLATE Object of the protected LSP (see [RFC4090],
6.1.1). Section 6.1.1).
o If reverse bypass tunnel is found and the primary LSP traffic is o If reverse bypass tunnel is found and the protected LSP traffic is
not already rerouted over the found bypass tunnel T2, the PRR R5 not already rerouted over the found bypass tunnel T2, the PRR R5
activates FRR reroute procedures to direct traffic over the found activates FRR reroute procedures to direct traffic over the found
bypass tunnel T2 in the reverse direction. In addition, the PRR bypass tunnel T2 in the reverse direction. In addition, the PRR
R5 also reroutes RSVP Resv over the bypass tunnel T2 in the R5 also reroutes RSVP Resv over the bypass tunnel T2 in the
reverse direction. reverse direction.
o If reverse bypass tunnel is not found, the PRR R5 immediately o If reverse bypass tunnel is not found, the PRR R5 immediately
tears down the primary LSP. tears down the protected LSP.
<- RESV <- RESV
[R1]---[R2]----[R3]--X--[R4]----[R5]---[R6] [R1]----[R2]----[R3]--X--[R4]----[R5]----[R6]
PATH -> \ / PATH -> \ /
+<<-------->>+ \ /
Bypass Tunnel T2 +<<------->>+
traffic + signaling Bypass Tunnel T2
traffic + signaling
Protected LSP: {R1-R2-R3-R4-R5-R6} Protected LSP: {R1-R2-R3-R4-R5-R6}
R3's Bypass T2: {R3-R5} R3's Bypass T2: {R3-R5}
Figure 3: Flow of RSVP signaling after FRR and re-corouted Figure 3: Flow of RSVP signaling after FRR and re-coroute
Figure 3 describes the path taken by the traffic and signaling after Figure 3 describes the path taken by the traffic and signaling after
completing re-coroute of data and signaling in the forward and completing re-coroute of data and signaling in the forward and
reverse paths described earlier. Node R4 will stop receiving the reverse paths described above. Node R4 will stop receiving the Path
Path and Resv messages and it will timeout the RSVP soft-state, and Resv messages and it will timeout the RSVP soft-state, however,
however, this will not cause the LSP to be torn down. RSVP signaling this will not cause the LSP to be torn down. RSVP signaling at node
at node R2 is not affected by the FRR and re-corouting. 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 If downstream MP R5 receives multiple RSVP Path messages through
multiple bypass tunnels (e.g. as a result of multiple failures), the multiple bypass tunnels (e.g. as a result of multiple failures), the
PRR SHOULD identify a bypass tunnel that terminates on the farthest PRR SHOULD identify a bypass tunnel that terminates on the farthest
downstream PLR along the protected LSP path (closest to the primary downstream PLR along the protected LSP path (closest to the protected
bidirectional LSP head-end) and activate the reroute procedures bidirectional LSP head-end) and activate the reroute procedures
mentioned above. mentioned above.
The downstream MP MAY optionally support re-corouting in data plane The downstream MP (upstream PLR) MAY optionally support re-corouting
as follows. If the downstream MP is pre-configured with in data plane as follows. If the downstream MP is pre-configured
bidirectional bypass tunnel, as soon as the MP node receives the with bidirectional bypass tunnel, as soon as the downstream MP
primary LSP packets on this bypass tunnel, it MAY switch the upstream receives the protected LSP packets on this bypass tunnel, it MAY
traffic on to this bypass tunnel. In order to identify the primary switch the upstream traffic on to this bypass tunnel. In order to
LSP packets through this bypass tunnel, Penultimate Hop Popping (PHP) identify the protected LSP packets through this bypass tunnel,
of the bypass tunnel MUST be disabled. The signaling procedure Penultimate Hop Popping (PHP) of the bypass tunnel MUST be disabled.
described above in this Section will still apply, and MP checks The signaling procedure described above in this Section will still
whether the primary LSP traffic and signaling is already rerouted apply, and downstream MP checks whether the protected LSP traffic and
over the found bypass tunnel, if not, perform the above signaling signaling is already rerouted over the found bypass tunnel, if not,
procedure. perform the above signaling procedure.
6.3. Revertive Behavior After Link Failure 6.3. Revertive Behavior After Fast Reroute
Revertive behavior as defined in [RFC4090], Section 6.5.2, is Revertive behavior as defined in [RFC4090], Section 6.5.2, is
applicable to node protection of GMPLS bidirectional LSPs. When applicable to the node protection of bidirectional GMPLS LSPs. When
using the local revertive mode, when downstream MP (R4) (before using the local revertive mode, after the link R3-R4 is restored,
re-corouting) and PRR (R5) (after re-corouting) receive Path messages following node behaviors apply:
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 o The downstream PLR R3 starts sending the Path messages and traffic
flow of the protected LSP over the restored link and stops sending
them over the bypass tunnel.
o The upstream PLR R4 starts sending the Resv messages and traffic
flow of the protected LSP over the restored link towards
downstream PLR R3 and forwarding the Path messages towards PRR R5
and stops sending them over the bypass tunnel.
o When upstream PLR R4 receives the protected LSP Path messages over
the restored link, if not already done, it starts sending Resv
messages and traffic flow over the restored link towards
downstream PLR R3 and forwarding the Path messages towards PRR R5
and stops sending them over the bypass tunnel.
o When PRR R5 receives the protected LSP Path messages over the
restored path, it starts sending Resv messages and traffic flow
over the restored path and stops sending them over the bypass
tunnel.
7. Unidirectional Link Failures
Unidirectional link failures may result in the traffic flowing on
asymmetric paths in the forward and reverse directions. In addition,
unidirectional link failures may cause RSVP soft-state timeout in the
control-plane in some cases. As an example, if the unidirectional
link failure is in the upstream direction (from R4 to R3 in Figures 1
and 2), the downstream PLR (node R3) can stop receiving the Resv
messages of the protected LSP from the upstream PLR (node R4 in
Figures 1 and 2) and this can cause RSVP soft-state timeout to occur
on the downstream PLR (node R3).
A unidirectional link failure in the downstream direction (from R3 to
R4 in Figure 1 and 2), does not cause RSVP soft-state timeout when
using the FRR procedures defined in this document, since the upstream
PLR (node R4 in Figure 1 and node R5 in Figure 2) triggers the
re-coroute procedure (defined in Section 6.2 of this document) after
receiving RSVP Path messages of the protected LSP over the bypass
tunnel from the downstream PLR (node R3 in Figures 1 and 2).
8. Message and Object Definitions
8.1. 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:TBA | Length | Bypass Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Bypass Destination Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: BYPASS ASSIGNMENT IPv4 RRO Subobject
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:TBA | Length | Bypass Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 Bypass Destination Address |
+ (16 bytes) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: BYPASS_ASSIGNMENT IPv6 RRO Subobject
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 8 bytes
with IPv4 address and 20 bytes with IPv6 object.
Bypass Tunnel ID
The bypass tunnel identifier (16 bits).
Bypass Destination Address
The bypass tunnel IPv4 or IPv6 destination address.
8.2. FRR Bypass Assignment Error Notify Message
New Error-code - FRR Bypass Assignment Error (value: TBA1) and its
sub-codes are defined for the ERROR_SPEC Object (C-Type 6) [RFC2205]
in this document, that is carried by the Notify message (Type 21)
defined in [RFC3473] Section 4.3. This Error is sent by the upstream
PLR to the downstream PLR to notify a bypass assignment error. In
the Notify message, the IP destination address is set to the node
address of the downstream PLR that had initiated the bypass
assignment. In the ERROR_SPEC Object, IP address is set to the node
address of the upstream PLR that detected the bypass assignment
error. This Error MUST NOT be sent in a Path Error message. This
Error does not cause protected LSP to be torn down.
9. Compatibility
New RSVP subobject BYPASS_ASSIGNMENT is defined for RECORD_ROUTE New RSVP subobject BYPASS_ASSIGNMENT is defined for RECORD_ROUTE
Object in this document. Per [RFC2205], nodes not supporting this Object in this document that is carried in the RSVP Path message.
subobject will ignore the subobject but forward it without Per [RFC3209], nodes not supporting this subobject will ignore the
modification. subobject but forward it without modification. As described in
Section 8, this subobject is not carried in the RSVP Resv message. A
new Notify message for FRR Bypass Assignment Error is defined in this
document. Nodes not supporting this message will ignore it but
forward it without modification.
8. Security Considerations 10. Security Considerations
This document introduces a new BYPASS_ASSIGNMENT subobject for the This document introduces a new BYPASS_ASSIGNMENT subobject for the
RECORD_ROUTE Object that is carried in an RSVP signaling message. RECORD_ROUTE Object that is carried in an RSVP signaling message.
Thus in the event of the interception of a signaling message, more Thus in the event of the interception of a signaling message, more
information about LSP's fast reroute protection can be deduced than information about LSP's fast reroute protection can be deduced than
was previously the case. This is judged to be a very minor security was previously the case. This is judged to be a very minor security
risk as this information is already available by other means. risk as this information is already available by other means.
Otherwise, this document introduces no additional security Otherwise, this document introduces no additional security
considerations. For general discussion on MPLS and GMPLS related considerations. For general discussion on MPLS and GMPLS related
security issues, see the MPLS/GMPLS security framework [RFC5920]. security issues, see the MPLS/GMPLS security framework [RFC5920].
9. IANA Considerations 11. IANA Considerations
11.1. BYPASS_ASSIGNMENT Subobject
IANA manages the "RSVP PARAMETERS" registry located at IANA manages the "RSVP PARAMETERS" registry located at
<http://www.iana.org/assignments/rsvp-parameters>. IANA is requested <http://www.iana.org/assignments/rsvp-parameters>. IANA is requested
to assign a value for the new BYPASS_ASSIGNMENT subobject in the to assign a value for the new BYPASS_ASSIGNMENT subobject in the
"Class Type 21 ROUTE_RECORD - Type 1 Route Record" registry. "Class Type 21 ROUTE_RECORD - Type 1 Route Record" registry.
This document introduces a new subobject for RECORD_ROUTE Object: This document introduces a new subobject for RECORD_ROUTE Object:
+--------+-------------------+---------+---------+---------------+ +--------+-------------------+---------+---------+---------------+
| Value | Description | Carried | Carried | Reference | | Type | Description | Carried | Carried | Reference |
| | | in Path | in Resv | | | | | in Path | in Resv | |
+--------+-------------------+---------+---------+---------------+ +--------+-------------------+---------+---------+---------------+
| TBA By | BYPASS_ASSIGNMENT | Yes | No | This document | | TBA By | BYPASS_ASSIGNMENT | Yes | No | This document |
| IANA | subobject | | | | | IANA | IPv4 subobject | | | |
+--------+-------------------+---------+---------+---------------+
| TBA By | BYPASS_ASSIGNMENT | Yes | No | This document |
| IANA | IPv6 subobject | | | |
+--------+-------------------+---------+---------+---------------+ +--------+-------------------+---------+---------+---------------+
10. References 11.2. FRR Bypass Assignment Error Notify Message
10.1. Normative References IANA maintains the "Resource Reservation Protocol (RSVP) Parameters"
registry (see <http://www.iana.org/assignments/rsvp-parameters>).
The "Error Codes and Globally-Defined Error Value Sub-Codes"
subregistry is included in this registry.
This registry has been extended for the new Error-code and Sub-codes
defined in this document as follows:
o Error-code TBA1: FRR Bypass Assignment Error
o Sub-code TBA2: Bypass Assignment Cannot Be Used
o Sub-code TBA3: Bypass Tunnel Not Found
o Sub-code TBA4: One-to-one Bypass Already In-use
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997. Functional Specification", RFC 2205, September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
skipping to change at page 15, line 33 skipping to change at page 18, line 33
January 2003. January 2003.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast [RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005. May 2005.
[RFC4561] Vasseur, J.P., Ed., Ali, Z., and S. Sivabalan, "Definition [RFC4561] Vasseur, J.P., Ed., Ali, Z., and S. Sivabalan, "Definition
of a Record Route Object (RRO) Node-Id Sub-Object", RFC of a Record Route Object (RRO) Node-Id Sub-Object", RFC
4561, June 2006. 4561, June 2006.
[RFC7551] Zhang, F., Ed., Jing, R., and Gandhi, R., Ed., "RSVP-TE 12.2. Informative References
Extensions for Associated Bidirectional LSPs", RFC 7551,
May 2015.
10.2. Informative References [RFC3471] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC
3471, January 2003.
[RFC4990] Shiomoto, K., Papneja, R., and R. Rabbat, "Use of
Addresses in Generalized Multiprotocol Label Switching
(GMPLS) Networks", RFC 4990, September 2007.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010. Networks", RFC 5920, July 2010.
[RFC6378] Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and [RFC6378] Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and
A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear
Protection", RFC 6378, October 2011. Protection", RFC 6378, October 2011.
[RFC7551] Zhang, F., Ed., Jing, R., and Gandhi, R., Ed., "RSVP-TE
Extensions for Associated Bidirectional LSPs", RFC 7551,
May 2015.
Acknowledgements Acknowledgements
Authors would like to thank George Swallow for his detailed and Authors would like to thank George Swallow for his detailed and
useful comments and suggestions. Authors would also like to thank useful comments and suggestions. Authors would also like to thank
Nobo Akiya, Loa Andersson, Matt Hartley and Gregory Mirsky for Nobo Akiya, Loa Andersson, Matt Hartley and Gregory Mirsky for
reviewing this document. reviewing this document. A special thanks to Adrian Farrel for his
thorough review of this document.
Contributors Contributors
Frederic Jounay Frederic Jounay
Orange CH Orange CH
EMail: frederic.jounay@orange.ch EMail: frederic.jounay@salt.ch
Manav Bhatia Ionos Networks Banglore India Manav Bhatia
Nokia
Banglore, India
EMail: manav@ionosnetworks.com EMail: manav.bhatia@nokia.com
Lizhong Jin Shanghai, China Lizhong Jin
Shanghai, China
EMail: lizho.jin@gmail.com EMail: lizho.jin@gmail.com
Authors' Addresses Authors' Addresses
Mike Taillon Mike Taillon
Cisco Systems, Inc. Cisco Systems, Inc.
EMail: mtaillon@cisco.com EMail: mtaillon@cisco.com
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