Internet Engineering Task Force H. Chen
Internet-Draft Huawei Technologies
Intended status: Standards Track N. So
Expires: January 17, 2013 Tata Communications
A. Liu
Ericsson
L. Liu
KDDI R&D Lab Inc.
July 16, 2012
Extensions to RSVP-TE for P2MP LSP Egress Local Protection
draft-chen-mpls-p2mp-egress-protection-06.txt
Abstract
This document describes extensions to Resource Reservation Protocol -
Traffic Engineering (RSVP-TE) for locally protecting egress nodes of
a Traffic Engineered (TE) point-to-multipoint (P2MP) Label Switched
Path (LSP) in a Multi-Protocol Label Switching (MPLS) and Generalized
MPLS (GMPLS) network.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 17, 2013.
Copyright Notice
Copyright (c) 2012 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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publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Conventions Used in This Document . . . . . . . . . . . . . . 4
4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. An Example of Egress Local Protection . . . . . . . . . . 4
4.2. Set up of Backup sub LSP . . . . . . . . . . . . . . . . . 5
4.3. Forwarding State for Backup sub LSP(s) . . . . . . . . . . 6
4.4. Detection of Egress Node Failure . . . . . . . . . . . . . 6
5. Egress Local Protection with FRR . . . . . . . . . . . . . . . 7
6. Representation of a Backup Sub LSP . . . . . . . . . . . . . . 7
6.1. EGRESS_BACKUP_SUB_LSP Object . . . . . . . . . . . . . . . 7
6.1.1. EGRESS_BACKUP_SUB_LSP IPv4 Object . . . . . . . . . . 8
6.1.2. EGRESS_BACKUP_SUB_LSP IPv6 Object . . . . . . . . . . 8
6.2. EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object . . . . . . 9
7. Path Message . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Format of Path Message . . . . . . . . . . . . . . . . . . 9
7.2. Processing of Path Message . . . . . . . . . . . . . . . . 10
8. Processing of Resv Message . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
RFC 4090 "Fast Reroute Extensions to RSVP-TE for LSP Tunnels"
describes two methods for protecting P2P LSP tunnels or paths at
local repair points. The first method is a one-to-one protection
method, where a detour backup P2P LSP for each protected P2P LSP is
created at each potential point of local repair, which is an
intermediate node between the ingress node and the egress node of the
protected LSP. The second method is a facility bypass backup
protection method, where a bypass backup P2P LSP tunnel is created
using MPLS label stacking to protect a potential failure point for a
set of P2P LSP tunnels. The bypass backup tunnel can protect a set
of P2P LSPs having similar backup constraints.
RFC 4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to
use the one-to-one protection method and facility bypass backup
protection method to protect a link or intermediate node failure on
the path of a P2MP LSP. However, there is no mention of locally
protecting any egress node failure in a protected P2MP LSP.
An existing method for protecting the egress nodes of a P2MP LSP sets
up a backup P2MP LSP from a backup ingress node to the backup egress
nodes, where each egress node is paired with a backup egress node and
protected by the backup egress node. The backup P2MP LSP carries the
same traffic as the P2MP LSP at the same time. A traffic receiver
from the P2MP LSP is normally connected to an egress node and its
paired backup egress node. It receives the traffic from the egress
node in normal situations.
The receiver selects the egress or backup egrss node for receiving
the traffic according to the route to the source through RPF. In a
normal situation, it selects the egress node. When the egress node
fails, it selects the backup egress for receiving the traffic since
the route to the source through the egress node is gone and the route
to the source through the backup egress node is active.
The main disadvantage of this method is that double network resources
such as double bandwidths are used for protecting the egress nodes
since the backup P2MP LSP consumes the same amount of network
resource as the primary P2MP LSP. The impact on network efficiency
can be significant in case of large P2MP deployments.
This document proposes a new method to locally protect the egress
nodes of a P2MP LSP, which is called Egress Local Protection. It
specifies the mechanism and extensions to RSVP-TE for locally
protecting an egress node of a Traffic Engineered (TE) point-to-
multipoint (P2MP) Label Switched Path through using a backup P2MP sub
LSP. The new method overcomes the disadvantages described above.
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The same extensions and mechanism can also be used to protect the
egress node of a TE P2P LSP.
2. Terminology
This document uses terminologies defined in RFC 2205, RFC 3031, RFC
3209, RFC 3473, RFC 4090, RFC 4461, and RFC 4875.
3. 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.
4. Mechanism
This section briefly describes a solution that locally protects an
egress node of a P2MP LSP through using a backup P2MP sub LSP. We
first show an example, and then present different parts of the
solution, which includes the creation of the backup sub LSP, the
forwarding state for the backup sub LSP, and the detection of a
failure in the egress node.
4.1. An Example of Egress Local Protection
Figure 1 below illustrates an example of using backup sub LSPs to
locally protect egress nodes of a P2MP LSP. The P2MP LSP is from
ingress node R1 to three egress nodes: L1, L2 and L3. It is
represented by double lines in the figure.
La, Lb and Lc are the designated backup egress nodes for the egress
nodes L1, L2 and L3 of the P2MP LSP respectively. In order to
distinguish an egress node (e.g., L1 in the figure) and a backup
egress node (e.g., La in the figure), an egress node is called a
primary egress node in the follwing description.
The backup sub LSP used to protect the primary egress node L1 is from
its previous hop node R3 to the backup egress node La. The backup
sub LSP used to protect the primary egress node L2 is from its
previous hop node R5 to the backup egress node Lb. The backup sub
LSP used to protect the primary egress node L3 is from its previous
hop node R5 to the backup egress node Lc via the intermediate node
Rc.
During normal operation, the traffic transported by the P2MP LSP is
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forwarded through R3 to L1, then delivered to its destination CE1.
When the failure of L1 is detected, R3 forwards the traffic to the
backup egress node La, which then delivers the traffic to its
destination CE1. The time for switching the traffic after L1 fails
is within tens of milliseconds.
L1's failure CAN be detected by a BFD session between L1 and R3.
[R2]=====[R3]=====[L1]----[CE1]
// \ /
// \ /
// \___[La]_/
//
//
//
//
+---[R1]====[R4]====[R5]=====[L2]----[CE2]
| |\\ \ /
| | \\ \ /
[S]--| | \\ \__[Lb]_/
| | \\
| | \\
| \\
| \\
| \\
| [L3]----[CE3]
| /
| /
[Rc]_______[Lc]_/
Figure 1: P2MP sub LSP for Locally Protecting Egress
4.2. Set up of Backup sub LSP
A backup egress node is designated for a primary egress node of a
LSP. The previous hop node of the primary egress node sets up a
backup sub LSP from itself to the backup egress node after receiving
the information about the backup egress node.
The previous hop node sets up the backup sub LSP, creates and
maintains its state in the same way as of setting up a source to leaf
(S2L) sub LSP from the signalling's point of view. It constructs and
sends a RSVP-TE PATH message along the path for the backup sub LSP,
receives and processes a RSVP-TE RESV message that responses to the
PATH message.
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4.3. Forwarding State for Backup sub LSP(s)
The forwarding state for the backup sub LSP is different from that
for a P2MP S2L sub LSP. After receiving the RSVP-TE RESV message for
the backup sub LSP, the previous hop node 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. It SHALL only be used after the
failure of the primary egress node.
Upon detection of the primary egress node failure, the state or flag
of the forwarding entry for the backup sub LSP is set to be active.
Thus, the previous hop node of the primary egress node will forward
the traffic to the backup egress node through the backup sub LSP,
which then send the traffic to its destination.
4.4. Detection of Egress Node Failure
The previous hop node of the primary egress node SHALL detect four
types of failures described below:
o The failure of the primary egress node (e.g. L1 in Figure 1)
o The failure of the link between the primary egress node and its
previous hop node (e.g. the link between R3 and L1 in Figure 1)
o The failure of the destination node for the primary egress node
(e.g. CE1 in Figure 1)
o The failure of the link between the primary egress node and its
destination node (e.g. the failure of the link between L1 and CE1
in Figure 1).
Failure of the primary egress node and the link between itself and
its previous hop node CAN be detected through a BFD session between
itself and its previous hop node in MPLS networks.
In the GMPLS networks where the control plane and data plane are
physically separated, the detection and localization of failures in
the physical layer can be achieved by introducing the link management
protocol (LMP) or assisting by performance monitoring devices.
Failure of the destination node and the link between the primary
egress node and the destination node CAN be detected by a BFD session
between the previous hop node and the destination node.
Upon detecting any above mentioned failures, the previous hop node
imports the traffic from the LSP into the backup sub LSP. The
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traffic is then delivered to its destination through the backup
egress node.
5. Egress Local Protection with FRR
RFC4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to use
RFC 4090 "Fast Reroute Extensions to RSVP-TE for LSP Tunnels" (FFR
for short) to locally protect failures in a link or intermediate node
of a P2MP LSP. However, there is not any standard that locally
protects the egresses of the P2MP LSP. The egress local protection
mechanism proposed in this document fills this gap. Thus, through
using the egress local protection and the FRR, we can locally protect
the egress nodes, all the links and the intermediate nodes of a P2MP
LSP. The traffic switchover time is within tens of milliseconds
whenever any of the egresses, the links and the intermediate nodes of
the P2MP LSP fails.
All the egress nodes of the P2MP LSP can be locally protected through
using the egress local protection. All the links and the
intermediate nodes of the LSP can be locally protected by using the
FRR. Note that the methods for locally protecting all the links and
the intermediate nodes of a P2MP LSP are out of scope of this
document.
6. Representation of a Backup Sub LSP
A backup sub LSP exists within the context of a P2MP LSP in a way
similar to a S2L sub LSP. It is identified by the P2MP LSP ID,
Tunnel ID, and Extended Tunnel ID in the SESSION object, the tunnel
sender address and LSP ID in the SENDER_TEMPLATE object, and the
backup sub LSP destination address in the EGRESS_BACKUP_SUB_LSP
object (to be defined in the section below).
An EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object (EB-SERO) is used to
optionally specify the explicit route of a backup sub LSP that is
from a previous hop node to a backup egress node. The EB-SERO is
defined in the following section.
6.1. EGRESS_BACKUP_SUB_LSP Object
An EGRESS_BACKUP_SUB_LSP object identifies a particular backup sub
LSP belonging to the LSP.
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6.1.1. EGRESS_BACKUP_SUB_LSP IPv4 Object
The class of the EGRESS_BACKUP_SUB_LSP IPv4 object is the same as
that of the S2L_SUB_LSP IPv4 object defined in RFC 4875. The C-Type
of the object is a new number 3, or may be another number assigned by
Internet Assigned Numbers Authority (IANA).
EGRESS_BACKUP_SUB_LSP Class = 50,
EGRESS_BACKUP_SUB_LSP_IPv4 C-Type = 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress Backup Sub LSP IPv4 destination address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Egress Backup Sub LSP IPv4 destination address
IPv4 address of the backup sub LSP destination is the backup
egress node.
Egress IPv4 address
IPv4 address of the egress node
6.1.2. EGRESS_BACKUP_SUB_LSP IPv6 Object
The class of the EGRESS_BACKUP_SUB_LSP IPv6 object is the same as
that of the S2L_SUB_LSP IPv6 object defined in RFC 4875. The C-Type
of the object is a new number 4, or may be another number assigned by
Internet Assigned Numbers Authority (IANA).
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EGRESS_BACKUP_SUB_LSP Class = 50,
EGRESS_BACKUP_SUB_LSP_IPv6 C-Type = 4
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress Backup Sub LSP IPv6 destination address |
| (16 bytes) |
| .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress IPv6 address |
| (16 bytes) |
| .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Egress Backup Sub LSP IPv6 destination address
IPv6 address of the backup sub LSP destination is the backup
egress node.
Egress IPv6 address
IPv6 address of the egress node
6.2. EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object
The format of an EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE (EB-SERO)
object is defined as identical to that of the ERO. The class of the
EB-SERO is the same as that of the SERO defined in RFC 4873. The EB-
SERO uses a new C-Type 3, or may use another number assigned by
Internet Assigned Numbers Authority (IANA). The formats of sub-
objects in an EB-SERO are identical to those of sub-objects in an ERO
defined in RFC 3209.
7. Path Message
This section describes extensions to the Path message defined in RFC
4875. The Path message is enhanced to transport the information
about a backup egress node to the previous hop node of a primary
egress node of a P2MP LSP through including an egress backup sub LSP
descriptor list.
7.1. Format of Path Message
The format of the enhanced Path 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 sub LSP descriptor list>]
The format of the egress backup sub LSP descriptor list in the
enhanced Path message is defined as follows.
<egress backup sub LSP descriptor list> ::=
<egress backup sub LSP descriptor>
[ <egress backup sub LSP descriptor list> ]
<egress backup sub LSP descriptor> ::=
<EGRESS_BACKUP_SUB_LSP>
[ <EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE> ]
7.2. Processing of Path Message
The ingress node of a LSP initiates a Path message with an egress
backup sub LSP descriptor list for protecting primary egress nodes of
the LSP. In order to protect a primary egress node of the LSP, the
ingress node MUST add an EGRESS_BACKUP_SUB_LSP object into the list.
The object contains the information about the backup egress node to
be used to protect the failure of the primary egress node. An
EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE object (EB-SERO), which
describes an explicit path to the backup egress node, SHALL follow
the EGRESS_BACKUP_SUB_LSP.
If the previous hop node of the primary egress node receives the Path
message with an egress backup sub LSP descriptor list, it generates a
new Path message based on the information in the
EGRESS_BACKUP_SUB_LSP (and according to EB-SERO if it exists)
containing the backup egress node.
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The format of this new Path message is the same as that of the Path
message defined in RFC 4875. This new Path message is used to signal
the segment of a special S2L sub-LSP from the previous hop node to
the backup egress node. The new Path message is sent to the next-hop
node along the path for the backup sub LSP.
If an intermediate node receives the Path message with an egress
backup sub LSP descriptor list. Then it MUST put the
EGRESS_BACKUP_SUB_LSP (according to EB-SERO if exists) containing a
backup egress into a Path message to be sent towards the backup
egress. This SHALL be done for each EGRESS_BACKUP_SUB_LSP containing
a backup egress node in the list.
When a primary egress node of the LSP receives the Path message with
an egress backup sub LSP descriptor list, it SHOULD ignore the egress
backup sub LSP descriptor list and generate a PathErr message.
8. Processing of Resv Message
The format of the Resv Message is not changed. The processing of the
Resv Message at the previous hop of a primary egress node is enhanced
for reporting the status of the primary egress protection.
The previous hop node of the primary egress node sets the protection
flags in the RRO IPv4/IPv6 Sub-object for the primary egress node
according to the status of the primary egress node and the backup sub
LSP protecting the primary egress node. For example, it will set the
node protection bit to one indicating that the primary egress node is
protected when the backup sub LSP to the backup egress node is set up
for protecting the primary egress node. It will set the bandwidth
protection bit to one when the backup sub LSP guarantees to provide
the desired bandwidth that is specified in the FAST_REROUTE object or
the bandwidth of the protected LSP.
9. IANA Considerations
TBD
10. Acknowledgement
The authors would like to thank Richard Li, Olufemi Komolafe, Rob
Rennison, Neil Harrison, Kannan Sampath, Yimin Shen, Ronhazli Adam
and Quintin Zhao for their valuable comments and suggestions on this
draft.
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11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3692, January 2004.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[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.
[P2MP FRR]
Le Roux, J., Aggarwal, R., Vasseur, J., and M. Vigoureux,
"P2MP MPLS-TE Fast Reroute with P2MP Bypass Tunnels",
draft-leroux-mpls-p2mp-te-bypass , March 1997.
11.2. Informative References
[RFC4461] Yasukawa, S., "Signaling Requirements for Point-to-
Multipoint Traffic-Engineered MPLS Label Switched Paths
(LSPs)", RFC 4461, April 2006.
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Authors' Addresses
Huaimo Chen
Huawei Technologies
Boston, MA
USA
Email: Huaimochen@huawei.com
Ning So
Tata Communications
2613 Fairbourne Cir.
Plano, TX 75082
USA
Email: ning.so@tatacommunications.com
Autumn Liu
Ericsson
CA
USA
Email: autumn.liu@ericsson.com
Lei Liu
KDDI R&D Lab Inc.
2-1-15
Ohara Fujimino-shi, Saitama
Japan
Email: le-liu@kddilabs.jp
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