Internet Engineering Task Force H. Chen
Internet-Draft Huawei Technologies
Intended status: Standards Track N. So
Expires: December 20, 2015 Tata Communications
A. Liu
Ericsson
T. Saad
Cisco Systems
F. Xu
Verizon
June 18, 2015
Extensions to RSVP-TE for LSP Egress Local Protection
draft-ietf-teas-rsvp-egress-protection-02.txt
Abstract
This document describes extensions to Resource Reservation Protocol -
Traffic Engineering (RSVP-TE) for locally protecting egress nodes of
a Traffic Engineered (TE) Label Switched Path (LSP), which is a
Point-to-Point (P2P) LSP or a Point-to-Multipoint (P2MP) LSP.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 20, 2015.
Copyright Notice
Copyright (c) 2015 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
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. An Example of Egress Local Protection . . . . . . . . . . 3
1.2. Egress Local Protection with FRR . . . . . . . . . . . . . 4
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 4
4.1. EGRESS_BACKUP Object . . . . . . . . . . . . . . . . . . . 4
4.1.1. EGRESS_BACKUP IPv4 Object . . . . . . . . . . . . . . 5
4.1.2. EGRESS_BACKUP IPv6 Object . . . . . . . . . . . . . . 5
4.1.3. P2P LSP ID Subobject . . . . . . . . . . . . . . . . . 6
4.1.4. Label Subobject . . . . . . . . . . . . . . . . . . . 7
4.2. Path Message . . . . . . . . . . . . . . . . . . . . . . . 7
5. Egress Protection Behaviors . . . . . . . . . . . . . . . . . 8
5.1. Ingress Behavior . . . . . . . . . . . . . . . . . . . . . 8
5.2. Transit Node and PLR Behavior . . . . . . . . . . . . . . 9
5.2.1. Signaling for One-to-One Protection . . . . . . . . . 9
5.2.2. Signaling for Facility Protection . . . . . . . . . . 10
5.2.3. Signaling for S2L Sub LSP Protection . . . . . . . . . 11
5.2.4. PLR Procedures during Local Repair . . . . . . . . . . 11
6. Considering Application Traffic . . . . . . . . . . . . . . . 12
6.1. A Typical Application . . . . . . . . . . . . . . . . . . 12
6.2. PLR Procedure for Applications . . . . . . . . . . . . . . 13
6.3. Egress Procedures for Applications . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8.1. A New Class Number . . . . . . . . . . . . . . . . . . . . 14
9. Co-authors . . . . . . . . . . . . . . . . . . . . . . . . . . 14
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 14
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 15
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
12.1. Normative References . . . . . . . . . . . . . . . . . . . 15
12.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
RFC 4090 describes two methods for protecting the transit nodes of a
P2P LSP: one-to-one and facility protection. RFC 4875 specifies how
to use them to protect the transit nodes of a P2MP LSP. However,
they do not mention any local protection for an egress of an LSP.
To protect the egresses of an LSP (P2P or P2MP), an existing approach
sets up a backup LSP from a backup ingress (or the ingress of the
LSP) to the backup egresses, where each egress is paired with a
backup egress and protected by the backup egress.
This approach uses more resources and provides slow fault recovery.
This document specifies extensions to RSVP-TE for local protection of
an egress of an LSP, which overcomes these disadvantages.
1.1. An Example of Egress Local Protection
Figure 1 shows an example of using backup LSPs to locally protect
egresses of a primary P2MP LSP from ingress R1 to two egresses: L1
and L2. The primary LSP is represented by star(*) lines and backup
LSPs by hyphen(-) lines.
La and Lb are the designated backup egresses for egresses L1 and L2
respectively. To distinguish an egress (e.g., L1) from a backup
egress (e.g., La), an egress is called a primary egress if needed.
The backup LSP for protecting L1 is from its upstream node R3 to
backup egress La. The one for protecting L2 is from R5 to Lb.
[R2]*****[R3]*****[L1]
* \ :.....: $ **** Primary LSP
* \ $ ---- Backup LSP
* \ [CE1] .... BFD Session
* \ $ $ Link
* \ $ $
* [La] $
*
[R1]******[R4]*******[R5]*****[L2]
$ \ :.....: $
$ \ $
[S] \ [CE2]
\ $
\ $
[Lb]
Figure 1: Backup LSP for Locally Protecting Egress
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During normal operations, the traffic carried by the P2MP LSP is sent
through R3 to L1, which delivers the traffic to its destination CE1.
When R3 detects the failure of L1, R3 switches the traffic to the
backup LSP to backup egress La, which delivers the traffic to CE1.
The time for switching the traffic is within tens of milliseconds.
The failure of a primary egress (e.g., L1 in the figure) may be
detected by its upstream node (e.g., R3 in the figure) through a BFD
between the upstream node and the egress in MPLS networks. Exactly
how the failure is detected is out of scope for this document.
1.2. Egress Local Protection with FRR
Using the egress local protection and the FRR, we can locally protect
the egresses, the links and the transit nodes of an LSP. The traffic
switchover time is within tens of milliseconds whenever an egress,
any of the links and the transit nodes of the LSP fails.
The egress nodes of the LSP can be locally protected via the egress
local protection. All the links and the transit nodes of the LSP can
be locally protected through using the FRR.
The egress local protection may be generalized and used with the
segment protection defined in RFC 4873. How it is generalized and
used is out of scope for this document.
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
3. Terminology
This document uses terminologies defined in RFC 2205, RFC 3209, RFC
4090 and RFC 4875.
4. Protocol Extensions
This section presents new RSVP objects.
4.1. EGRESS_BACKUP Object
A new object EGRESS_BACKUP is defined for egress local protection.
It contains a backup egress for a primary egress.
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4.1.1. EGRESS_BACKUP IPv4 Object
Class = EGRESS_BACKUP, EGRESS_BACKUP_IPv4 C-Type = 1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Backup Egress IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Primary Egress IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved (must be zero) | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ (Subobjects) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Backup Egress IPv4 address:
IPv4 address of the backup egress node
o Primary Egress IPv4 address:
IPv4 address of the primary egress node
o Flags
0x01 S2L Sub LSP Backup Desired
0x02 Other Sending UA Label
Flag "S2L Sub LSP Backup Desired" is used to indicate if S2L Sub LSP
(ref to RFC 4875) is desired for protecting an egress of a P2MP LSP.
Flag "Other Sending UA Label" is used to indicate if another protocol
is desired for sending a label as a UA label from a primary egress to
a backup egress.
The Subobjects are TLVs. One of them is P2P LSP ID IPv4 subobject.
Another is Label subobject.
4.1.2. EGRESS_BACKUP IPv6 Object
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Class = EGRESS_BACKUP, EGRESS_BACKUP_IPv6 C-Type = 2
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Backup Egress IPv6 address (16 bytes) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Primary Egress IPv6 address (16 bytes) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved (must be zero) | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ (Subobjects) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Backup Egress IPv6 address:
IPv6 address of the backup egress node
o Primary Egress IPv6 address:
IPv6 address of the primary egress node
o Flags
0x01 S2L Sub LSP Backup Desired
0x02 Other Sending UA Label
4.1.3. P2P LSP ID Subobject
A P2P LSP ID subobject contains the information for identifying a
backup LSP tunnel.
4.1.3.1. P2P LSP ID IPv4 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 | Length | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| P2P LSP Tunnel Egress IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: 0x01 for P2P LSP ID IPv4
o Length: The total length of the subobject in bytes, which is 12.
o Tunnel ID:
A 16-bit identifier that is constant over the life of the tunnel
o P2P LSP Tunnel Egress IPv4 Address:
IPv4 address of the egress of the tunnel
o Extended Tunnel ID:
A 4-byte identifier being constant over the life of the tunnel
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4.1.3.2. P2P LSP ID IPv6 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 | Length | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ P2P LSP Tunnel Egress IPv6 Address (16 bytes) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Extended Tunnel ID (16 bytes) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: 0x02 for P2P LSP ID IPv6
o Length: The total length of the subobject in bytes, which is 36.
o Tunnel ID:
A 16-bit identifier that is constant over the life of the tunnel
o P2P LSP Tunnel Egress IPv6 Address:
IPv6 address of the egress of the tunnel
o Extended Tunnel ID:
A 16-byte identifier being constant over the life of the tunnel
4.1.4. Label 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 | Length | Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ (sub-TLVs ) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: 0x03 for Label
o Length: The total length of the subobject in bytes.
o Flags: 0x01 = Global Label
o Label: Value of Label
4.2. Path Message
A Path message is enhanced to carry the information about a backup
egress for a primary egress of an LSP by including an egress backup
descriptor list. The format of the message is illustrated below.
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<Path Message> ::= <Common Header> [ <INTEGRITY> ]
[ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ...]
[ <MESSAGE_ID> ]<SESSION> <RSVP_HOP> <TIME_VALUES>
[ <EXPLICIT_ROUTE> ]
<LABEL_REQUEST> [ <PROTECTION> ] [ <LABEL_SET> ...]
[ <SESSION_ATTRIBUTE> ] [ <NOTIFY_REQUEST> ]
[ <ADMIN_STATUS> ] [ <POLICY_DATA> ... ]
<sender descriptor> [<S2L sub-LSP descriptor list>]
[<egress backup descriptor list>]
The egress backup descriptor list in the message is defined below.
It is a sequence of EGRESS_BACKUP objects, each of which describes a
pair of a primary egress and a backup egress.
<egress backup descriptor list> ::=
<egress backup descriptor>
[ <egress backup descriptor list> ]
<egress backup descriptor> ::= <EGRESS_BACKUP>
5. Egress Protection Behaviors
5.1. Ingress Behavior
To protect a primary egress of an LSP, the ingress MUST set the
"label recording desired" flag and the "node protection desired" flag
in the SESSION_ATTRIBUTE object.
If one-to-one backup or facility backup is desired to protect a
primary egress of an LSP, the ingress MUST include a FAST_REROUTE
object and set the "One-to-One Backup Desired" or "Facility Backup
Desired" flag respectively.
If S2L Sub LSP backup is desired to protect a primary egress of a
P2MP LSP, the ingress MUST include an EGRESS_BACKUP object and set
the "S2L Sub LSP Backup Desired" flag.
If another protocol is desired for sending a label as a upstream
assigned label to a backup egress, the ingress MUST set the "Other
Sending UA Label" flag.
A backup egress SHOULD be configured on the ingress of an LSP to
protect a primary egress of the LSP.
The ingress MUST send a Path message for the LSP with the objects
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above and an optional egress backup descriptor list for protecting
egresses of the LSP. For each primary egress of the LSP to be
protected, the ingress MUST add an EGRESS_BACKUP object into the list
if the backup egress is given. The object MUST contain the primary
egress and the backup egress for protecting the primary egress.
5.2. Transit Node and PLR Behavior
If a transit node of an LSP receives the Path message with an egress
backup descriptor list and it is not an upstream node of any primary
egress of the LSP, it MUST forward the list unchanged.
If the transit node is the upstream node of a primary egress to be
protected, it determines the backup egress, obtains a path for the
backup LSP and sets up the backup LSP along the path.
The PLR (upstream node of the primary egress) MUST extract the backup
egress from the respective EGRESS_BACKUP object in the egress backup
descriptor list. If no matching EGRESS_BACKUP object is found or the
list is empty, the PLR applies a local policy to determine the backup
egress and MUST add an EGRESS_BACKUP object with the backup egress
and primary egress into a Path message to the primary egress.
After obtaining the backup egress, the PLR computes a backup path
from itself to the backup egress. It excludes the primary egress to
be protected when computing the path. Thus the PLR will not select
any path via the primary egress.
The PLR MUST provide one-to-one backup protection for the primary
egress if the "One-to-One Backup Desired" flag is set in the message;
otherwise, it MUST provide facility backup protection if the
"Facility Backup Desired flag" is set.
The PLR MUST set the protection flags in the RRO Sub-object for the
primary egress in the Resv message according to the status of the
primary egress and the backup LSP protecting the primary egress. For
example, it sets the "local protection available" and the "node
protection" flag indicating that the primary egress is protected when
the backup LSP is up and ready for protecting the primary egress.
5.2.1. Signaling for One-to-One Protection
The behavior of the upstream node of a primary egress of an LSP as a
PLR is the same as that of a PLR for one-to-one backup described in
RFC 4090 except for that the upstream node as a PLR creates a backup
LSP from itself to a backup egress.
If the LSP is a P2MP LSP and a primary egress of the LSP is also a
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transit node (i.e., bud node), the upstream node of the primary
egress as a PLR creates a backup LSP from itself to each of the next
hops of the primary egress.
When the PLR detects the failure of the primary egress, it switches
the packets from the primary LSP to the backup LSP to the backup
egress. For the failure of the bud node of a P2MP LSP, the PLR also
switches the packets to the backup LSPs to the bud node's next hops,
where the packets are merged into the primary LSP.
5.2.2. Signaling for Facility Protection
Except for backup LSP and downstream label, the behavior of the
upstream node of the primary egress of a primary LSP as a PLR follows
the PLR behavior for facility backup described in RFC 4090.
For a number of primary P2P LSPs going through the same PLR to the
same primary egress, the primary egress of these LSPs MAY be
protected by one backup LSP from the PLR to the backup egress
designated for protecting the primary egress.
The PLR selects or creates a backup LSP from itself to the backup
egress. If there is a backup LSP that satisfies the constraints
given in the Path message, then this one is selected; otherwise, a
new backup LSP to the backup egress is created.
After getting the backup LSP, the PLR associates the backup LSP with
a primary LSP for protecting its primary egress. The PLR records
that the backup LSP is used to protect the primary LSP against its
primary egress failure and MUST include an EGRESS_BACKUP object in
the Path message to the primary egress. The object MUST contain the
backup egress and the backup LSP ID. It indicates that the primary
egress MUST send the backup egress the service label as UA label if
there is a service carried by the LSP and the primary LSP label as UA
label if the label is not implicit null.
A UA label MAY be sent via RSVP or another protocol (e.g., BGP). If
"Other Sending UA Label" flag is one, the primary egress MUST send
the UA labels to the backup egress through another protocol;
otherwise, UA labels MUST be sent via RSVP.
After receiving the Path message with the EGRESS_BACKUP, the primary
egress MUST include the information about the UA labels in the Resv
message with an EGRESS_BACKUP object. When the PLR receives the Resv
message with the information about the UA labels, it MUST include the
information in the Path message for the backup LSP to the backup
egress. Thus the UA labels are sent to the backup egress from the
primary egress via RSVP.
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When the PLR detects the failure of the primary egress, it redirects
the packets from the primary LSP into the backup LSP to backup egress
and MUST keep the primary LSP label from the primary egress in the
label stack if the label is not implicit null. The backup egress
MUST deliver the packets to the same destinations as the primary
egress using the backup LSP label as context label and the labels
under as UA labels.
5.2.3. Signaling for S2L Sub LSP Protection
The S2L Sub LSP Protection uses a S2L Sub LSP (ref to RFC 4875) as a
backup LSP to protect a primary egress of a P2MP LSP. The PLR MUST
determine to protect a primary egress of a P2MP LSP via S2L sub LSP
protection when it receives a Path message with flag "S2L Sub LSP
Backup Desired" set.
The PLR MUST set up the backup S2L sub LSP to the backup egress,
create and maintain its state in the same way as of setting up a
source to leaf (S2L) sub LSP defined in RFC 4875 from the signaling's
point of view. It computes a path for the backup LSP from itself to
the backup egress, constructs and sends a Path message along the
path, receives and processes a Resv message responding to the Path
message.
After receiving the Resv message for the backup LSP, the PLR creates
a forwarding entry with an inactive state or flag called inactive
forwarding entry. This inactive forwarding entry is not used to
forward any data traffic during normal operations.
When the PLR detects the failure of the primary egress, it changes
the forwarding entry for the backup LSP to active. Thus, the PLR
forwards the traffic to the backup egress through the backup LSP,
which sends the traffic to its destination.
5.2.4. PLR Procedures during Local Repair
When the upstream node of a primary egress of an LSP as a PLR detects
the failure of the primary egress, it follows the procedures defined
in section 6.5 of RFC 4090. It SHOULD notify the ingress about the
failure of the primary egress in the same way as a PLR notifies the
ingress about the failure of a transit node.
Moreover, the PLR MUST let the upstream part of the primary LSP stay
after the primary egress fails through sending Resv message to its
upstream node along the primary LSP. The downstream part of the
primary LSP from the PLR to the primary egress SHOULD be removed.
In the local revertive mode, the PLR SHOULD re-signal each of the
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primary LSPs that were routed over the restored resource once it
detects that the resource is restored. Every primary LSP
successfully re-signaled along the restored resource SHOULD be
switched back.
6. Considering Application Traffic
This section focuses on the application traffic carried by P2P LSPs.
When a primary egress of a P2MP LSP fails, the application traffic
carried by the P2MP LSP is delivered to the same destination by the
backup egress since the inner label if any for the traffic is a
upstream assigned label for every egress of the P2MP LSP.
6.1. A Typical Application
L3VPN is a typical application. An existing solution (refer to
Figure 2) for protecting L3VPN traffic against egress failure
includes: 1) A multi-hop BFD session between ingress R1 and egress L1
of primary LSP; 2) A backup LSP from ingress R1 to backup egress La;
3) La sends R1 VPN backup label and related information via BGP; 4)
R1 has a VRF with two sets of routes: one uses primary LSP and L1 as
next hop; the other uses backup LSP and La as next hop.
CE1,CE2 in [R2]*****[R3]*****[L1] **** Primary LSP
one VPN * : $ ---- Backup LSP
* .................: $ .... BFD Session
[R1] ..: [CE2] $ Link
$ \ $ $
$ \ $
[CE1] [R4]-----[R5]-----[La](BGP sends R1 VPN backup label)
Figure 2: Protect Egress for L3VPN Traffic
In normal operations, R1 sends the traffic from CE1 through primary
LSP with VPN label received from L1 as inner label to L1, which
delivers the traffic to CE2 using VPN label.
When R1 detects the failure of L1, R1 sends the traffic from CE1 via
backup LSP with VPN backup label received from La as inner label to
La, which delivers the traffic to CE2 using VPN backup label.
A new solution (refer to Figure 3) with egress local protection for
protecting L3VPN traffic includes: 1) A BFD session between R3 and
egress L1 of primary LSP; 2) A backup LSP from R3 to backup egress
La; 3) L1 sends La VPN label as UA label and related information; 4)
L1 and La is virtualized as one. This can be achieved by configuring
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a same local address on L1 and La, using the address as a destination
of the LSP and BGP next hop for VPN traffic.
CE1,CE2 in [R2]*****[R3]*****[L1] **** Primary LSP
one VPN * \ :.....: $ ---- Backup LSP
* \ $ .... BFD Session
[R1] \ [CE2] $ Link
$ \ $ $
$ \ $
[CE1] [La](VPN label from L1 as UA label)
Figure 3: Locally Protect Egress for L3VPN Traffic
When R3 detects L1's failure, R3 sends the traffic from primary LSP
via backup LSP to La, which delivers the traffic to CE2 using VPN
label as UA label under the backup LSP label as a context label.
6.2. PLR Procedure for Applications
When the PLR gets a backup LSP from itself to a backup egress for
protecting a primary egress of a primary LSP, it includes an
EGRESS_BACKUP object in the Path message for the primary LSP. The
object contains the ID information of the backup LSP and indicates
that the primary egress sends the backup egress the application
traffic label (e.g., VPN label) as UA label when needed.
6.3. Egress Procedures for Applications
When a primary egress of an LSP sends the ingress of the LSP a label
for an application such as a VPN, it sends the backup egress for
protecting the primary egress the label as a UA label. Exactly how
the label is sent is out of scope for this document.
When the backup egress receives a UA label from the primary egress,
it adds a forwarding entry with the label into the LFIB for the
primary egress. When the backup egress receives a packet from the
backup LSP, it uses the top label as a context label to find the LFIB
for the primary egress and the inner label to deliver the packet to
the same destination as the primary egress according to the LFIB.
7. Security Considerations
In principle this document does not introduce new security issues.
The security considerations pertaining to RFC 4090, RFC 4875 and
other RSVP protocols remain relevant.
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Note that protecting a primary egress of a P2P LSP carrying service
traffic through a backup egress requires that the backup egress trust
the primary egress for the information received for a service label
as UA label.
8. IANA Considerations
IANA is requested to administer the assignment of new values defined
in this document and summarized in this section.
8.1. A New Class Number
IANA maintains a registry called "Class Names, Class Numbers, and
Class Types" under "Resource Reservation Protocol-Traffic Engineering
(RSVP-TE) Parameters". IANA is requested to assign a new Class
Number for new object EGRESS_BACKUP as follows:
+===============+===============+=======================+
| Class Names | Class Numbers | Class Types |
+===============+===============+=======================+
| EGRESS_BACKUP | TBD1 (>192) | 1: EGRESS_BACKUP_IPv4 |
| | +-----------------------+
| | | 2: EGRESS_BACKUP_IPv6 |
+---------------+---------------+-----------------------+
IANA is requested to assign Types for new TLVs in the new objects as
follows:
Type Name Allowed in
1 P2P_LSP_ID_IPv4 TLV EGRESS_BACKUP_IPv4
2 P2P_LSP_ID_IPv6 TLV EGRESS_BACKUP_IPv6
3 Label TLV EGRESS_BACKUP
9. Co-authors
Lu Huang, Mehmet Toy, Lei Liu, Zhenbin Li
10. Contributors
Boris Zhang
Telus Communications
200 Consilium Pl Floor 15
Toronto, ON M1H 3J3
Canada
Email: Boris.Zhang@telus.com
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Nan Meng
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: mengnan@huawei.com
Vic Liu
China Mobile
No.32 Xuanwumen West Street, Xicheng District
Beijing, 100053
China
Email: liuzhiheng@chinamobile.com
11. Acknowledgement
The authors would like to thank Richard Li, Nobo Akiya, Lou Berger,
Jeffrey Zhang, Lizhong Jin, Ravi Torvi, Eric Gray, Olufemi Komolafe,
Michael Yue, Daniel King, Rob Rennison, Neil Harrison, Kannan
Sampath, Yimin Shen, Ronhazli Adam and Quintin Zhao for their
valuable comments and suggestions on this draft.
12. References
12.1. Normative References
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
Label Assignment and Context-Specific Label Space",
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RFC 5331, August 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
12.2. Informative References
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, May 2007.
Authors' Addresses
Huaimo Chen
Huawei Technologies
Boston, MA
USA
Email: huaimo.chen@huawei.com
Ning So
Tata Communications
2613 Fairbourne Cir.
Plano, TX 75082
USA
Email: ningso01@gmail.com
Autumn Liu
Ericsson
CA
USA
Email: autumn.liu@ericsson.com
Tarek Saad
Cisco Systems
Email: tsaad@cisco.com
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Fengman Xu
Verizon
2400 N. Glenville Dr
Richardson, TX 75082
USA
Email: fengman.xu@verizon.com
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