Internet DRAFT - draft-gandhi-ccamp-gmpls-restoration-lsp
draft-gandhi-ccamp-gmpls-restoration-lsp
CCAMP Working Group Rakesh Gandhi, Ed.
Internet-Draft Zafar Ali
Intended status: Informational Gabriele Maria Galimberti
Expires: October 25, 2014 Cisco Systems, Inc.
Xian Zhang
Huawei
April 23, 2014
RSVP-TE Signaling For GMPLS Restoration LSP
draft-gandhi-ccamp-gmpls-restoration-lsp-04
Abstract
In transport networks, there are requirements where Generalized
Multi-Protocol Label Switching (GMPLS) end-to-end recovery scheme
needs to employ restoration Label Switched Path (LSP) while keeping
resources for the working and/or protecting LSPs reserved in the
network after the failure.
This document reviews how the LSP association is to be provided using
Resource Reservation Protocol - Traffic Engineering (RSVP-TE)
signaling in the context of GMPLS end-to-end recovery when using
restoration LSP where failed LSP is not torn down. No new procedures
or mechanisms are defined by this document, and it is strictly
informative in nature.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Signaling Restoration LSP Association . . . . . . . . . . . . 5
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) [RFC3473] extends
Multi-Protocol Label Switching (MPLS) to include support for
different switching technologies. These switching technologies
provide several protection schemes [RFC4426][RFC4427] (e.g., 1+1, 1:N
and M:N). Resource Reservation Protocol - Traffic Engineering (RSVP-
TE) signaling has been extended to support various GMPLS recovery
schemes [RFC4872][RFC4873], to establish Label Switched Paths (LSPs),
typically for working LSP and protecting LSP. [RFC4427] Section 7
specifies various schemes for GMPLS recovery.
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 document, "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 document 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 document 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. As defined, the PROTECTION object is used to identify
primary and secondary LSPs using S bit and protecting and working
LSPs using P bit. Furthermore, [RFC4872] defines the usage of
ASSOCIATION object for associating GMPLS working and protecting LSPs.
[RFC6689] Section 2.2 reviews the procedure for providing LSP
associations for GMPLS end-to-end recovery and covers the schemes
where the failed working LSP and/or protecting LSP are torn down.
This document reviews how the LSP association is to be provided for
GMPLS end-to-end recovery when using restoration LSP where working
and protecting LSP resources are kept reserved in the network after
the failure.
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2. Signaling Restoration LSP Association
Where 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, 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]. Specifically, restoration LSP being used as a working LSP
is signaled with P bit cleared and being used as a protecting LSP is
signaled with P bit set.
As discussed in Section 1 of this document, [RFC6689] Section 2.2
reviews the procedure for providing LSP associations for the GMPLS
end-to-end recovery scheme using restoration LSP where the failed
working LSP and/or protecting LSP are torn down.
3. IANA Considerations
This document makes no request for IANA action.
4. Security Considerations
This document reviews procedures defined in [RFC4872] and [RFC6689]
and does not define any new procedure. As such, no new security
considerations are introduced in this document.
5. Acknowledgement
The authors would like to thank George Swallow for the discussions on
the GMPLS restoration.
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6. References
6.1. Normative References
[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 Papadimitriou, D., "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.
6.2. Informative References
[RFC4426] Lang, J., Rajagopalan, B., and Papadimitriou, D.,
"Generalized Multiprotocol Label Switching (GMPLS)
Recovery Functional Specification", RFC 4426, March 2006.
[RFC4427] Mannie, E., and Papadimitriou, D., "Recovery (Protection
and Restoration) Terminology for Generalized
Multi-Protocol Label Switching, RFC 4427, March 2006.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and Farrel,
A., "GMPLS Segment Recovery", RFC 4873, May 2007.
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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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