Internet DRAFT - draft-ietf-mpls-summary-frr-rsvpte
draft-ietf-mpls-summary-frr-rsvpte
MPLS Working Group M. Taillon
Internet-Draft Cisco Systems, Inc.
Updates: 4090 (if approved) T. Saad, Ed.
Intended status: Standards Track Juniper Networks
Expires: August 29, 2020 R. Gandhi
Cisco Systems, Inc.
A. Deshmukh
Juniper Networks
M. Jork
128 Technology
V. Beeram
Juniper Networks
February 26, 2020
RSVP-TE Summary Fast Reroute Extensions for LSP Tunnels
draft-ietf-mpls-summary-frr-rsvpte-09
Abstract
This document updates RFC 4090 for the Resource Reservation Protocol
(RSVP) Traffic-Engineering (TE) procedures defined for facility
backup protection. The updates include extensions that reduce the
amount of signaling and processing that occurs during Fast Reroute
(FRR), and subsequently, improves scalability when undergoing FRR
convergence after a link or node failure. These extensions allow the
RSVP message exchange between the Point of Local Repair (PLR) and the
Merge Point (MP) nodes to be independent of the number of protected
Label Switched Paths (LSPs) traversing between them when facility
bypass FRR protection is used. The signaling extensions are fully
backwards compatible with nodes that do not support them.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2020.
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Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Acronyms and Abbreviations . . . . . . . . . . . . . . . 4
3. Extensions for Summary FRR Signaling . . . . . . . . . . . . 5
3.1. B-SFRR-Ready Extended ASSOCIATION Object . . . . . . . . 6
3.1.1. IPv4 B-SFRR-Ready Extended ASSOCIATION ID . . . . . . 7
3.1.2. IPv6 B-SFRR-Ready Extended ASSOCIATION ID . . . . . . 8
3.1.3. Processing Rules for B-SFRR-Ready Extended
ASSOCIATION Object . . . . . . . . . . . . . . . . . 9
3.2. B-SFRR-Active Extended ASSOCIATION Object . . . . . . . . 10
3.2.1. IPv4 B-SFRR-Active Extended ASSOCIATION ID . . . . . 11
3.2.2. IPv6 B-SFRR-Active Extended ASSOCIATION ID . . . . . 12
3.3. Signaling Procedures Prior to Failure . . . . . . . . . . 14
3.3.1. PLR Signaling Procedure . . . . . . . . . . . . . . . 15
3.3.2. MP Signaling Procedure . . . . . . . . . . . . . . . 15
3.4. Signaling Procedures Post Failure . . . . . . . . . . . . 16
3.4.1. PLR Signaling Procedure . . . . . . . . . . . . . . . 16
3.4.2. MP Signaling Procedure . . . . . . . . . . . . . . . 17
3.5. Refreshing Summary FRR Active LSPs . . . . . . . . . . . 18
4. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 18
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
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1. Introduction
The Fast Reroute (FRR) procedures defined in [RFC4090] describe the
mechanisms for the Point of Local Repair (PLR) to reroute traffic and
signaling of a protected RSVP-TE Label Switched Path (LSP) onto the
bypass tunnel in the event of a TE link or node failure. Such
signaling procedures are performed individually for each affected
protected LSP. This may eventually lead to control plane scalability
and latency issues on the PLR and/or the Merge Point (MP) nodes due
to limited memory and CPU processing resources. This condition is
exacerbated when the failure affects a large number of protected LSPs
that traverse the same PLR and MP nodes.
For example, in a large-scale RSVP-TE LSPs deployment, a single Label
Switched Router (LSR) acting as a PLR node may host tens of thousands
of protected RSVP-TE LSPs egressing the same protected link, and also
act as an MP node for a similar number of LSPs that ingress on the
same link. In the event of the failure of the link or neighbor node,
the RSVP-TE control plane of the node (when acting as a PLR node)
becomes busy rerouting protected LSPs over the bypass tunnel(s) in
one direction, and (when acting as an MP node) becomes busy merging
RSVP states from signaling received over bypass tunnels for LSP(s) in
the reverse direction. Subsequently, the head-end Label Edge Routers
(LERs) that are notified of the local repair at downstream LSR will
attempt to (re)converge the affected RSVP-TE LSPs onto newly computed
paths - possibly traversing the same previously affected LSR(s). As
a result, the RSVP-TE control plane becomes overwhelmed by the amount
of FRR RSVP-TE processing overhead following the link or node
failure, and due to other control plane protocol(s) (e.g. the IGP)
that undergo convergence on the same node at the same time too.
Today, each protected RSVP-TE LSP is signaled individually over the
bypass tunnel after FRR. The changes introduced in this document
allow the PLR node to assign multiple protected LSPs to a bypass
tunnel group and to communicate this assignment to the MP, such that
upon failure, the signaling over the bypass tunnel happens on bypass
tunnel group(s). New extensions are defined in this document to
update the procedures defined in [RFC4090] for facility backup
protection to enable the MP node to become aware of the PLR node's
bypass tunnel assignment group(s) and to allow FRR procedures between
the PLR and the MP nodes to be signaled and processed on per bypass
tunnel group(s).
As defined in [RFC2961], Summary Refresh procedures use MESSAGE_ID to
refresh the RSVP Path and Resv states to help with scaling. The
Summary FRR procedures introduced in this document build on those
concepts to allow the MESSAGE_ID(s) to be exchanged on per bypass
tunnel assignment group, and continue use Summary Refresh procedures
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while reducing the amount of messaging that occurs after rerouting
signaling over the bypass tunnel post FRR.
2. Conventions Used in This Document
2.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.2. Acronyms and Abbreviations
The reader is assumed to be familiar with terms and abbreviations
used in [RFC3209] and [RFC4090].
The following abbreviations are also used in this document:
LSR: Label Switching Router
LER: Label Edge Router
MPLS: Multiprotocol Label Switching
LSP: Label Switched Path
MP: Merge Point node as defined in [RFC4090]
PLR: Point of Local Repair node as defined in [RFC4090]
FRR: Fast Reroute as defined in [RFC4090]
B-SFRR-Ready: Bypass Summary FRR Ready Extended ASSOCIATION
object. Added by the PLR node for each LSP protected by the
bypass tunnel.
B-SFRR-Active: Bypass Summary FRR Active Extended ASSOCIATION
object. Used to notify the MP node that one or more groups of
protected LSP(s) have been rerouted over the associated bypass
tunnel.
MTU: Maximum transmission unit.
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3. Extensions for Summary FRR Signaling
The RSVP ASSOCIATION object is defined in [RFC4872] as a means to
associate LSPs with each other. For example, in the context of
GMPLS-controlled LSP(s), the ASSOCIATION object is used to associate
a recovery LSP with the LSP(s) it is protecting. The Extended
ASSOCIATION object is introduced in [RFC6780] to expand on the
possible usage of the ASSOCIATION object and generalize the
definition of the Extended Association ID field.
This document defines the use of the Extended ASSOCIATION object to
carry the Summary FRR information and associate the protected LSP(s)
with the bypass tunnel that protects them. Two new Association Types
for the Extended ASSOCIATION object, and new Extended Association IDs
are proposed in this document to describe the Bypass Summary FRR
Ready (B-SFRR-Ready) and the Bypass Summary FRR Active (B-SFRR-
Active) associations.
The PLR node creates and manages the Summary FRR LSP groups
(identified by Bypass_Group_Identifiers) and shares the group
identifier(s) with the MP via signaling.
A PLR node SHOULD assign the same Bypass_Group_Identifier to all
protected LSPs provided that the protected LSPs:
o share the same outgoing protected interface,
o are protected by the same bypass tunnel, and
o are assigned the same tunnel sender address that is used for
backup path identification after FRR as described in [RFC4090].
This minimizes the number of bypass tunnel SFRR groups, and optimizes
the amount of signaling that occurs between the PLR and the MP nodes
after FRR.
A PLR node that supports Summary FRR procedures adds an Extended
ASSOCIATION object with B-SFRR-Ready Extended Association ID in the
RSVP Path message of the protected LSP. The PLR node adds the
protected LSP Bypass_Group_Identifier, information from the assigned
bypass tunnel, and MESSAGE_ID object into the B-SFRR-Ready Extended
Association ID. The MP uses the information contained in the
received B-SFRR-Ready Extended Association ID to refresh and merge
the protected LSP Path state after FRR occurs.
An MP node that supports Summary FRR procedures adds the B-SFRR-Ready
Extended ASSOCIATION object and respective Extended Association ID in
the RSVP Resv message of the protected LSP to acknowledge the PLR's
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bypass tunnel assignment, and provide the MESSAGE_ID object that the
MP node will use to refresh the protected LSP Resv state after FRR
occurs.
The MP maintains the PLR node group assignments learned from
signaling, and acknowledges the group assignments to the PLR node via
signaling. Once the PLR node receives the group assignment
acknowledgment from the MP, the FRR signaling can proceed based on
Summary FRR procedures as described in this document.
The B-SFRR-Active Extended ASSOCIATION object with Extended
Association ID is sent by the PLR node after activating the Summary
FRR procedures. The B-SFRR-Active Extended ASSOCIATION object with
Extended Association ID is sent within the RSVP Path message of the
bypass tunnel to inform the MP node that one or more groups of
protected LSPs protected by the bypass tunnel are now being rerouted
over the bypass tunnel.
3.1. B-SFRR-Ready Extended ASSOCIATION Object
The Extended ASSOCIATION object is populated using the rules defined
below to associate a protected LSP with the bypass tunnel that is
protecting it when Summary FRR procedures are enabled.
The Association Type, Association ID, and Association Source MUST be
set as defined in [RFC4872] for the ASSOCIATION Object. More
specifically:
Association Source:
The Association Source is set to an address of the PLR node.
Association Type:
A new Association Type is defined for B-SFRR-Ready as follows:
Value Type
------- ------
(TBD-1) Bypass Summary FRR Ready Association (B-SFRR-Ready)
The Extended ASSOCIATION object's Global Association Source MUST be
set according to the rules defined in [RFC6780].
The B-SFRR-Ready Extended ASSOCIATION ID is populated by the PLR node
when performing Bypass Summary FRR Ready association for a protected
LSP. The rules governing its population are described in the
subsequent sections.
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3.1.1. IPv4 B-SFRR-Ready Extended ASSOCIATION ID
The IPv4 Extended ASSOCIATION ID for the B-SFRR-Ready association
type is carried inside the IPv4 Extended ASSOCIATION object and has
the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Tunnel_ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Source_IPv4_Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Destination_IPv4_Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Group_Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MESSAGE_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The IPv4 Extended ASSOCIATION ID for B-SFRR-Ready
Bypass_Tunnel_ID: 16 bits
The bypass tunnel identifier.
Reserved: 16 bits
Reserved for future use. MUST be set to zero when sending
and ignored on receipt.
Bypass_Source_IPv4_Address: 32 bits
The bypass tunnel source IPV4 address.
Bypass_Destination_IPv4_Address: 32 bits
The bypass tunnel destination IPV4 address.
Bypass_Group_Identifier: 32 bits
The bypass tunnel group identifier that is assigned to the
LSP.
MESSAGE_ID
A MESSAGE_ID object as defined by [RFC2961].
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3.1.2. IPv6 B-SFRR-Ready Extended ASSOCIATION ID
The IPv6 Extended ASSOCIATION ID for the B-SFRR-Ready association
type is carried inside the IPv6 Extended ASSOCIATION object and has
the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Tunnel_ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Bypass_Source_IPv6_Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Bypass_Destination_IPv6_Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Group_Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MESSAGE_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The IPv6 Extended ASSOCIATION ID for B-SFRR-Ready
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Bypass_Tunnel_ID: 16 bits
The bypass tunnel identifier.
Reserved: 16 bits
Reserved for future use. MUST be set to zero when sending
and ignored on receipt.
Bypass_Source_IPv6_Address: 128 bits
The bypass tunnel source IPV6 address.
Bypass_Destination_IPv6_Address: 128 bits
The bypass tunnel destination IPV6 address.
Bypass_Group_Identifier: 32 bits
The bypass tunnel group identifier that is assigned to the
LSP.
MESSAGE_ID
A MESSAGE_ID object as defined by [RFC2961].
3.1.3. Processing Rules for B-SFRR-Ready Extended ASSOCIATION Object
A PLR node assigns a bypass tunnel and Bypass_Group_Identifier for
each protected LSP. The same Bypass_Group_Identifier is used for the
set of protected LSPs that share the same bypass tunnel, traverse the
same egress link and are not already rerouted. The PLR node MUST
generate a MESSAGE_ID object with Epoch and Message_Identifier set
according to [RFC2961]. The MESSAGE_ID object flags MUST be cleared
when transmitted by the PLR node and ignored when received at the MP
node.
A PLR node MUST generate a new Message_Identifier each time the
contents of the B-SFRR-Ready Extended ASSOCIATION ID changes (e.g.
when the PLR node changes the bypass tunnel assignment).
A PLR node notifies the MP node of the bypass tunnel assignment via
adding a B-SFRR-Ready Extended ASSOCIATION object and Extended
Association ID in the RSVP Path message for the protected LSP using
procedures described in Section 3.3.
An MP node acknowledges the assignment to the PLR node by signaling
the B-SFRR-Ready Extended ASSOCIATION object and Extended Association
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ID within the RSVP Resv message of the protected LSP. With the
exception of the MESSAGE_ID objects, all other fields of the received
in the B-SFRR-Ready Extended ASSOCIATION ID in the RSVP Path message
are copied into the B-SFRR-Ready Extended ASSOCIATION ID to be added
in the Resv message. The MESSAGE_ID object is set according to
[RFC2961]. The MESSAGE_ID object flags MUST be cleared when
transmitted by the MP node and ignored when received at the PLR node.
A new Message_Identifier MUST be used to acknowledge an updated PLR
node's assignment.
A PLR node considers the protected LSP as Summary FRR capable only if
all the fields in the B-SFRR-Ready Extended ASSOCIATION ID that are
sent in the RSVP Path message match the fields received in the RSVP
Resv message (with exception of the MESSAGE_ID). If the fields do
not match, or if B-SFRR-Ready Extended ASSOCIATION object is absent
in a subsequent refresh, the PLR node MUST consider the protected LSP
as not Summary FRR capable.
A race condition may arise for a previously Summary FRR capable
protected LSP when the MP node triggers a refresh that does not
contain the B-SFRR-Ready Extended ASSOCIATION object, while at the
same time, the PLR triggers Summary FRR procedures due to a fault
occurring concurrently. In this case, it is possible that the PLR
triggers Summary FRR procedurees on the protected LSP before it can
receive and process the refresh from the MP node. As a result, the
MP will receive a Srefresh with a Message_Identifier that is not
associated with any state. As per [RFC2961], this results in the MP
generating an Srefresh NACK for this Message_Identifier and sending
it back to the PLR. The PLR processes the Srefresh NACK and replays
the full Path state associated with the Message_Identifier, and
subsequently recovering from this condition.
3.2. B-SFRR-Active Extended ASSOCIATION Object
The Extended ASSOCIATION object for B-SFRR-Active association type is
populated by a PLR node to indicate to the MP node (bypass tunnel
destination) that one or more groups of Summary FRR protected LSPs
that are being protected by the bypass tunnel are being rerouted over
the bypass tunnel.
The B-SFRR-Active Extended ASSOCIATION object is carried in the RSVP
Path message of the bypass tunnel and signaled downstream towards the
MP (bypass tunnel destination).
The Association Type, Association ID, and Association Source MUST be
set as defined in [RFC4872] for the ASSOCIATION Object. More
specifically:
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Association Source:
The Association Source is set to an address of the PLR node.
Association Type:
A new Association Type is defined for B-SFRR-Active as follows:
Value Type
------- ------
(TBD-2) Bypass Summary FRR Active Association (B-SFRR-Active)
Extended ASSOCIATION ID for B-SFRR-Active:
The B-SFRR-Active Extended ASSOCIATION ID is
populated by the PLR node for the Bypass Summary FRR Active
association. The rules to populate the Extended ASSOCIATION ID
in this case are described below.
3.2.1. IPv4 B-SFRR-Active Extended ASSOCIATION ID
The IPv4 Extended ASSOCIATION ID for the B-SFRR-Active association
type is carried inside the IPv4 Extended ASSOCIATION object and has
the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num-BGIDs | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Group_Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : |
// : //
| : |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Group_Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// RSVP_HOP_Object //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TIME_VALUES //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel sender address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: The IPv4 Extended ASSOCIATION ID for B-SFRR-Active
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Num-BGIDs: 16 bits
Number of Bypass_Group_Identifier fields.
Reserved: 16 bits
Reserved for future use.
Bypass_Group_Identifier: 32 bits each
A Bypass_Group_Identifier that was previously signaled by the PLR
using the Extended ASSOCIATION object in the B-SFRR-Ready Extended
Association ID. One or more Bypass_Group_Identifiers MAY be
included.
RSVP_HOP_Object: Class 3, as defined by [RFC2205]
Replacement RSVP HOP object to be applied to all LSPs associated
with each of the following Bypass_Group_Identifiers. This
corresponds to C-Type = 1 for IPv4 RSVP HOP.
TIME_VALUES object: Class 5, as defined by [RFC2205]
Replacement TIME_VALUES object to be applied to all LSPs
associated with each of the preceding Bypass_Group_Identifiers
after receiving the B-SFRR-Active Extended ASSOCIATION Object.
IPv4 tunnel sender address:
The IPv4 address that the PLR node sets to identify backup path(s)
as described in Section 6.1.1 of [RFC4090]. This address is
applicable to all groups identified by Bypass_Group_Identifier(s)
carried in the B-SFRR-Active Extended ASSOCIATION ID.
3.2.2. IPv6 B-SFRR-Active Extended ASSOCIATION ID
The IPv6 Extended ASSOCIATION ID for the B-SFRR-Active association
type is carried inside the IPv6 Extended ASSOCIATION object and has
the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num-BGIDs | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Group_Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : |
// : //
| : |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bypass_Group_Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// RSVP_HOP_Object //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TIME_VALUES //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ IPv6 tunnel sender address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: The IPv6 Extended ASSOCIATION ID for B-SFRR-Active
Num-BGIDs: 16 bits
Number of Bypass_Group_Identifier fields.
Reserved: 16 bits
Reserved for future use.
Bypass_Group_Identifier: 32 bits each
A Bypass_Group_Identifier that was previously signaled by the PLR
using the Extended ASSOCIATION object in the B-SFRR-Ready Extended
Association ID. One or more Bypass_Group_Identifiers MAY be
included.
RSVP_HOP_Object: Class 3, as defined by [RFC2205]
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Replacement RSVP HOP object to be applied to all LSPs associated
with each of the following Bypass_Group_Identifiers. This
corresponds to C-Type = 2 for IPv6 RSVP HOP.
TIME_VALUES object: Class 5, as defined by [RFC2205]
Replacement TIME_VALUES object to be applied to all LSPs
associated with each of the following Bypass_Group_Identifiers
after receiving the B-SFRR-Active Extended ASSOCIATION Object.
IPv6 tunnel sender address:
The IPv6 address that the PLR node sets to identify backup path(s)
as described in Section 6.1.1 of [RFC4090]. This address is
applicable to all groups identified by Bypass_Group_Identifier(s)
carried in the B-SFRR-Active Extended ASSOCIATION ID.
3.3. Signaling Procedures Prior to Failure
Before Summary FRR procedures can be used, a handshake MUST be
completed between the PLR and MP nodes. This handshake is performed
using the Extended ASSOCIATION object that carries the B-SFRR-Ready
Extended Association ID in both the RSVP Path and Resv messages of
the protected LSP.
The facility backup method introduced in [RFC4090] takes advantage of
MPLS label stacking (PLR node imposing additional MPLS label post
FRR) to allow rerouting of protected traffic over the backup path.
The backup path may have stricter MTU requirement and due to label
stacking at PLR node, the protected traffic may exceed the backup
path MTU. The operator is assumed to engineer their network to allow
rerouting of protected traffic and the additional label stacking at
PLR node to not exceed the backup path MTU.
When using procedures defined in this document, the PLR node MUST
ensure the bypass tunnel assignment can satisfy the protected LSP MTU
requirements post FRR. This avoids any packets from being dropped
due to exceeding the MTU size of the backup path after traffic is
rerouted on to the bypass tunnel post the failure. Section 2.6 in
[RFC3209] describes a mechanism to determine whether a node needs to
fragment or drop a packet when it exceeds the Path MTU discovered
using RSVP signaling on primary LSP path. A PLR can leverage the
RSVP discovered Path MTU on the backup and primary LSP paths to
ensure MTU is not exceeded before or after rerouting the protected
traffic on to the bypass tunnel.
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3.3.1. PLR Signaling Procedure
The B-SFRR-Ready Extended ASSOCIATION object is added by each PLR
node in the RSVP Path message of the protected LSP to record the
bypass tunnel assignment. This object is updated every time the PLR
node updates the bypass tunnel assignment and that triggers an RSVP
Path change message.
Upon receiving an RSVP Resv message with B-SFRR-Ready Extended
ASSOCIATION object, the PLR node checks if the expected sub-objects
from the B-SFRR-Ready Extended ASSOCIATION ID are present. If
present, the PLR node determines if the MP has acknowledged the
current PLR node's assignment.
To be a valid acknowledgement, the received B-SFRR-Ready Extended
ASSOCIATION ID contents within the RSVP Resv message of the protected
LSP MUST match the latest B-SFRR-Ready Extended ASSOCIATION object
and Association ID contents that the PLR node had sent within the
RSVP Path message (with exception of the MESSAGE_ID).
Note, when forwarding an RSVP Resv message upstream, the PLR node
SHOULD remove any/all B-SFRR-Ready Extended ASSOCIATION objects whose
Bypass_Source_IPv4_Address or Bypass_Source_IPv6_Address field
matches any of the PLR node addresses.
3.3.2. MP Signaling Procedure
Upon receiving an RSVP Path message with a B-SFRR-Ready Extended
ASSOCIATION object, an MP node processes all (there may be multiple
PLR nodes for a single MP node) B-SFRR-Ready Extended ASSOCIATION
objects that have the MP node address as Bypass Destination address
in the Extended Association ID.
The MP node first ensures the existence of the bypass tunnel and that
the Bypass_Group_Identifier is not already FRR active. That is, an
LSP cannot join a group that is already FRR rerouted.
The MP node builds a mirrored Summary FRR Group database per PLR node
by associating the Bypass_Source_IPv4_Address or
Bypass_Source_IPv6_Address that is carried in the IPv4 or IPv6 B-
SFRR-Ready Extended ASSOCIATION IDs respectively.
The MESSAGE_ID is extracted and recorded for the protected LSP Path
state. The MP node signals a B-SFRR-Ready Extended Association
object and Extended Association ID in the RSVP Resv message of the
protected LSP. With the exception of the MESSAGE_ID objects, all
other fields of the received B-SFRR-Ready Extended ASSOCIATION object
in the RSVP Path message are copied into the B-SFRR-Ready Extended
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ASSOCIATION object to be added in the Resv message. The MESSAGE_ID
object is set according to [RFC2961] with the Flags being clear.
Note, an MP may receive more than one RSVP Path message with the B-
SFRR-Ready Extended ASSOCIATION object from different upstream PLR
node(s). In this case, the MP node is expected to save all the
received MESSAGE_IDs received from the different upstream PLR
node(s). After a failure, the MP node determines and activates the
state(s) associated with the Bypass_Group_Identifier(s) received in
the RSVP Path message containing B-SFRR-Active Extended ASSOCIATION
object that is signaled over the bypass tunnel from the PLR node, as
described Section 3.4
When forwarding an RSVP Path message downstream, the MP node SHOULD
remove any/all B-SFRR-Ready Extended ASSOCIATION object(s) whose
Bypass_Destination_IPv4_Address or Bypass_Destination_IPv6_Address
field matches any of the MP node addresses.
3.4. Signaling Procedures Post Failure
Upon detection of a fault (egress link or node failure) the PLR node
will first perform the object modification procedures described by
Section 6.4.3 of [RFC4090] for all affected protected LSPs. For the
Summary FRR capable LSPs that are assigned to the same bypass tunnel
a common RSVP_HOP and SENDER_TEMPLATE MUST be used.
The PLR node MUST signal non-Summary FRR capable LSPs over the bypass
tunnel before signaling the Summary FRR capable LSPs. This is needed
to allow for the case where the PLR node recently changed a bypass
assignment and the MP has not processed the change yet.
The B-SFRR-Active Extended ASSOCIATION object is sent within the RSVP
Path message of the bypass tunnel to reroute RSVP state of Summary
FRR capable LSPs.
3.4.1. PLR Signaling Procedure
After a failure event, when using the Summary FRR path signaling
procedures, an individual RSVP Path message is not signaled for each
Summary FRR LSP. Instead, to reroute Summary FRR LSPs via the bypass
tunnel, the PLR node adds the B-SFRR-Active Extended Association
object in the RSVP Path message of the RSVP session of the bypass
tunnel.
The RSVP_HOP_Object field in the B-SFRR-Active Extended ASSOCIATION
ID is set to a common object that will be applied to all LSPs
associated with the Bypass_Group_Identifiers that are carried in the
B-SFRR-Active Extended ASSOCIATION ID.
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The PLR node adds the Bypass_Group_Identifier(s) of group(s) that
have common group attributes, including the tunnel sender address, to
the same B-SFRR-Active Extended ASSOCIATION ID. Note that multiple
ASSOCIATION objects, each carrying a B-SFRR-Active Extended
ASSOCIATION ID, can be carried within a single RSVP Path message of
the bypass tunnel and sent towards the MP as described in [RFC6780].
The previously received MESSAGE_ID(s) from the MP are activated on
the PLR. As a result, the PLR starts sending Srefresh messages
containing the specific Message_identifier(s) for the states to be
refreshed.
3.4.2. MP Signaling Procedure
Upon receiving an RSVP Path message with a B-SFRR-Active Extended
Association object, the MP performs normal merge point processing for
each protected LSP associated with each Bypass_Group_Identifier, as
if it had received an individual RSVP Path message for that LSP.
For each Summary FRR capable LSP that is being merged, the MP first
modifies the Path state as follows:
1. The RSVP_HOP object is copied from the RSVP_HOP_Object field in
the B-SFRR-Active Extended ASSOCIATION ID.
2. The TIME_VALUES object is copied from the TIME_VALUES field in
the B-SFRR-Active Extended ASSOCIATION ID. The TIME_VALUES
object contains the refresh time of the PLR node to generate
refreshes and that would have exchanged in a Path message sent to
the MP after the failure when no Summary FRR procedures are in
effect.
3. The tunnel sender address field in the SENDER_TEMPLATE object is
copied from the tunnel sender address field of the B-SFRR-Active
Extended ASSOCIATION ID.
4. The ERO object is modified as per Section 6.4.4 of [RFC4090].
Once the above modifications are completed, the MP node performs
the merge processing as per [RFC4090].
5. The previously received MESSAGE_ID(s) from the PLR node are
activated. The MP is allowed to send Srefresh messages
containing the specific Message_identifier(s) for the states to
be refreshed.
A failure during merge processing of any individual rerouted LSP MUST
result in an RSVP Path Error message.
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An individual RSVP Resv message for each successfully merged Summary
FRR LSP is not signaled. The MP node SHOULD immediately use Summary
Refresh procedures to refresh the protected LSP Resv state.
3.5. Refreshing Summary FRR Active LSPs
Refreshing of Summary FRR active LSPs is performed using Summary
Refresh as defined by [RFC2961].
4. Backwards Compatibility
The (Extended) ASSOCIATION object is defined in [RFC4872] with a
class number in the form 11bbbbbb, where b=0 or 1. This ensures
compatibility with non-supporting node(s) in accordance with the
procedures specified in [RFC2205], Section 3.10 for unknown-class
objects, Such nodes will ignore the object and forward it without any
modification.
5. Security Considerations
This document updates an existing RSVP object. Thus, in the event of
the interception of a signaling message, slightly more information
could be deduced about the state of the network than was previously
the case.
When using procedures defined in this document, FRR signaling for
rerouting of protected LSP(s) states on to the bypass tunnel can be
performed on a group of protected LSP(s) with a single RSVP message.
This allows an intruder to potentially impact and manipulate a set of
protected LSP that are assigned to the same bypass tunnel group.
Note that such attack is even possible without the mechanisms
proposed in this document; albeit, at an extra cost resulting from
the excessive per LSP signaling that will occur.
Existing mechanisms for maintaining the integrity and authenticity of
RSVP protocol messages [RFC2747] can be applied. Other
considerations mentioned in [RFC4090] and [RFC5920] also apply.
6. IANA Considerations
IANA maintains the "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Parameters" registry. The "Association Type" sub-
registry is included in this registry.
This registry has been updated by new Association Type for Extended
ASSOCIATION Object defined in this document as follows:
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Value Name Reference
----- ---- ---------
TBD-1 B-SFRR-Ready Association Section 3.1
TBD-2 B-SFRR-Active Association Section 3.2
7. Acknowledgments
The authors would like to thank Alexander Okonnikov, Loa Andersson,
Lou Berger, Eric Osborne, Gregory Mirsky, Mach Chen for reviewing and
providing valuable comments to this document.
8. Contributors
Nicholas Tan
Arista Networks
Email: ntan@arista.com
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <https://www.rfc-editor.org/info/rfc2205>.
[RFC2747] Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
Authentication", RFC 2747, DOI 10.17487/RFC2747, January
2000, <https://www.rfc-editor.org/info/rfc2747>.
[RFC2961] Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi, F.,
and S. Molendini, "RSVP Refresh Overhead Reduction
Extensions", RFC 2961, DOI 10.17487/RFC2961, April 2001,
<https://www.rfc-editor.org/info/rfc2961>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
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[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
DOI 10.17487/RFC4090, May 2005,
<https://www.rfc-editor.org/info/rfc4090>.
[RFC4872] Lang, J., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
Ed., "RSVP-TE Extensions in Support of End-to-End
Generalized Multi-Protocol Label Switching (GMPLS)
Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
<https://www.rfc-editor.org/info/rfc4872>.
[RFC6780] Berger, L., Le Faucheur, F., and A. Narayanan, "RSVP
ASSOCIATION Object Extensions", RFC 6780,
DOI 10.17487/RFC6780, October 2012,
<https://www.rfc-editor.org/info/rfc6780>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<https://www.rfc-editor.org/info/rfc5920>.
Authors' Addresses
Mike Taillon
Cisco Systems, Inc.
Email: mtaillon@cisco.com
Tarek Saad (editor)
Juniper Networks
Email: tsaad@juniper.net
Rakesh Gandhi
Cisco Systems, Inc.
Email: rgandhi@cisco.com
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Abhishek Deshmukh
Juniper Networks
Email: adeshmukh@juniper.net
Markus Jork
128 Technology
Email: mjork@128technology.com
Vishnu Pavan Beeram
Juniper Networks
Email: vbeeram@juniper.net
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