CCAMP Working Group Rakesh Gandhi, Ed.
Internet-Draft Zafar Ali
Intended status: Informational Gabriele Maria Galimberti
Expires: September 7, 2014 Cisco Systems, Inc.
Xian Zhang
Huawei
March 6, 2014
RSVP-TE Signaling For GMPLS Restoration LSP
draft-gandhi-ccamp-gmpls-restoration-lsp-03
Abstract
In transport networks, there are requirements where Generalized
Multi-Protocol Label Switching (GMPLS) end-to-end recovery scheme
needs to employ restoration LSP while keeping resources for the
working and/or protecting LSPs reserved in the network after the
failure. This draft describes Resource reSerVation Protocol -
Traffic Engineering (RSVP-TE) signaling for GMPLS end-to-end recovery
when using restoration LSP when failed LSP is not torn down.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 5
3. Restoration LSP Signaling Procedure . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative references . . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) extends MPLS to
include support for different switching technologies [RFC3473]. These
switching technologies provide several protection schemes
[RFC4426][RFC4427] (e.g., 1+1, 1:N and M:N). GMPLS RSVP-TE signaling
has been extended to support various recovery schemes to establish
Label Switched Paths (LSPs) [RFC4872][RFC4873], typically working LSP
and protecting LSP. [RFC4427] Section 7 specifies various schemes
for GMPLS restoration.
In GMPLS recovery schemes generally considered, restoration LSP is
signaled after the failure has been detected and notified on the
working LSP. In non-revertive recovery mode, working LSP is assumed
to be removed from the network before restoration LSP is signaled.
For revertive recovery mode, a restoration LSP is signaled while
working LSP and/or protecting LSP are not torn down in control plane
due to a failure. In transport networks, as working LSPs are
typically signaled over a nominal path, service providers would like
to keep resources associated with the working LSPs reserved. This is
to make sure that the service (working LSP) can use the nominal path
when the failure is repaired to provide deterministic behaviour and
guaranteed Service Level Agreement (SLA). Consequently, revertive
recovery mode is usually preferred by recovery schemes used in
transport networks.
As defined in [RFC4872] and being considered in this draft, "fully
dynamic rerouting switches normal traffic to an alternate LSP that is
not even partially established only after the working LSP failure
occurs. The new alternate route is selected at the LSP head-end
node, it may reuse resources of the failed LSP at intermediate nodes
and may include additional intermediate nodes and/or links."
One example of the recovery scheme considered in this draft is 1+R
recovery. The 1+R recovery is exemplified in Figure 1. In this
example, working LSP on path A-B-C-Z is pre-established. Typically
after a failure detection and notification on the working LSP, a
second LSP on path A-H-I-J-Z is established as a restoration LSP.
Unlike protection LSP, restoration LSP is signaled per need basis.
A --- B --- C --- Z
\ /
H --- I --- J
Figure 1: An example of 1+R recovery scheme
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During failure switchover with 1+R recovery scheme, in general,
working LSP resources are not released and working and restoration
LSPs coexist in the network. Nonetheless, working and restoration
LSPs can share network resources. Typically when failure is
recovered on the working LSP, restoration LSP is no longer required
and torn down (e.g., revertive mode).
Another example of the recovery scheme considered in this draft is
1+1+R. In 1+1+R, a restoration LSP is signaled for the working LSP
and/or the protecting LSP after the failure has been detected and
notified on the working LSP or the protecting LSP. The 1+1+R
recovery is exemplified in Figure 2. In this example, working LSP on
path A-B- C-Z and protecting LSP on path A-D-E-F-Z are pre-
established. After a failure detection and notification on a working
LSP or protecting LSP, a third LSP on path A-H-I-J-Z is established
as a restoration LSP. The restoration LSP in this case provides
protection against a second order failure. Restoration LSP is torn
down when the failure on the working or protecting LSP is repaired.
D --- E --- F
/ \
A --- B --- C --- Z
\ /
H --- I --- J
Figure 2: An example of 1+1+R recovery scheme
[RFC4872] Section 14 defines PROTECTION object for GMPLS recovery
signaling. The PROTECTION object is used to identify primary and
secondary LSPs using S bit and protecting and working LSPs using P
bit. [RFC4872] and [RFC6689] define the usage of ASSOCIATION object
for further associating GMPLS working and protecting LSPs. However,
these existing methods do not specify how to identify restoration LSP
when working/protecting LSPs are not torn down.
This draft describes procedures for identifying the restoration LSP
for GMPLS end-to-end recovery where working and protecting LSP
resources are kept reserved in the network after the failure.
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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 [RFC2119].
3. Restoration LSP Signaling Procedure
Where GMPLS recovery scheme needs to employ restoration LSP while
keeping resources for the working and/or protecting LSPs reserved in
the network after the failure, restoration LSP is signaled with
ASSOCIATION object with the association ID set to the LSP ID of the
LSP it is restoring. For example, when a restoration LSP is signaled
for a working LSP, the ASSOCIATION object in the restoration LSP
contains the association ID set to the LSP ID of the working LSP.
Similarly, when a restoration LSP is signaled for a protecting LSP,
the ASSOCIATION object in the restoration LSP contains the
association ID set to the LSP ID of the protecting LSP.
The procedure for signaling the PROTECTION object is specified in
[RFC4872] and is not changed by this document. Restoration LSP being
used as a working LSP is signaled with P bit cleared and used as a
protecting LSP is signaled with P bit set.
GMPLS recovery scheme where the failed working LSP and/or protecting
LSP need to be torn down follows the procedures defined in [RFC6689].
4. IANA Considerations
This document makes no request for IANA action.
5. Security Considerations
This document introduces no additional security considerations. For
a general discussion on MPLS and GMPLS related security issues, see
the MPLS/GMPLS security framework [RFC5920]. In addition, the
considerations specified in [RFC4872] will apply.
6. Acknowledgement
The authors would like to thank George Swallow for the discussion on
the GMPLS restoration.
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7. References
7.1. 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.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC4872] Lang, J., Rekhter, Y., and D. Papadimitriou, "RSVP-TE
Extensions in Support of End-to-End Generalized Multi-
Protocol Label Switching (GMPLS) Recovery", RFC 4872, May
2007.
[RFC6689] Berger, L, "Usage of the RSVP ASSOCIATION Object", RFC
6689, July 2012.
7.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4426] Lang, J., Rajagopalan B., and D.Papadimitriou, Editors,
"Generalized Multiprotocol Label Switching (GMPLS)
Recovery Functional Specification", RFC 4426, March 2006.
[RFC4427] Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery
(Protection and Restoration) Terminology for Generalized
Multi-Protocol Label Switching, RFC 4427, March 2006.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, May 2007.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
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Authors' Addresses
Rakesh Gandhi (editor)
Cisco Systems, Inc.
Email: rgandhi@cisco.com
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
Gabriele Maria Galimberti
Cisco Systems, Inc.
Email: ggalimbe@cisco.com
Xian Zhang
Huawei Technologies
Research Area F3-1B,
Huawei Industrial Base,
Shenzhen, 518129, China
Email: zhang.xian@huawei.com
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