Abstract

An important requirement in the IP-based control of time-division multiplexing (TDM) optical transport networks is to utilize the in-built protection capabilities of synchronous optical network (SONET) unidirectional path-switched rings (UPSRs) and to automate the UPSR-protected path setup in mixed mesh–ring networks. This requires modifications to existing IP signaling and routing protocols and new processing rules at the network nodes. Here we leverage IP routing and signaling and multiprotocol label switching (MPLS) fast-reroute techniques for accurately advertising UPSR ring topologies to remote nodes and dynamically establishing UPSR-protected paths across a transport network. Our proposal also makes a NUT1-like (nonpreemptible unprotected traffic) feature possible in UPSRs, which allows for efficient utilization of UPSR protection bandwidth. We achieve this by encoding UPSR-specific information in the open shortest-path-first (OSPF) link state advertisements and in signaling messages of the Resource Reservation Protocol (RSVP) with TE extensions. In addition, we modify the signaling and routing state machines at the nodes to interpret and process this information to perform UPSR topology discovery and path computation. The uniqueness of our proposals is that the algorithms and the rules specified here allow for existing IP-based protocols [such as those within the generalized MPLS (GMPLS) framework, which currently applies to mesh networks] to be efficiently adapted for this context while still achieving our objective of exploiting UPSR-protection capabilities.

© 2002 Optical Society of America

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References

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  1. GR-1400-CORE, “SONET dual-fed unidirectional path switched ring (UPSR) equipment generic criteria,” Issue 2 (Bellcore, January 1999), <a href="http://www.telcordia.com/">http://www.telcordia.com/</a>.
  2. GR-1230-CORE, “SONET bi-directional line switched ring (BLSR) equipment generic criteria,” Issue 4 (Bellcore, December 1998), <a href="http://www.telcordia.com/">http://www.telcordia.com</a>.
  3. G. Swallow, “MPLS advantages for traffic engineering,” IEEE Commun. Mag. (December 1999), pp. 54–57.
  4. D. Awduche and Y. Rekhter, “Multiprotocol lambda switching: combining MPLS traffic engineering control with optical crossconnects,” IEEE Commun. Mag. (March 2001), pp. 111–116.
  5. A. Bannerjee, J. Drake, J.P. Lang, B. Turner, D. Awduche, L. Berger, K. Kompella, and Y. Rekhter, "Generalized multi protocol label switching: an overview of signaling enhancements and recovery techniques,' IEEE Commun. Mag. (July 2001), pp. 144–151.
  6. A. Banerjee, J. Drake, J. P. Lang, B. Turner, K. Kompella, and Y. Rekhter, “Generalized multi protocol label switching: an overview of routing and management enhancements,” IEEE Commun. Mag. (January 2001), pp. 144–150.
  7. G. Bernstein, J. Yates, and D. Saha “IP-centric control and management of optical transport networks,” IEEE Commun. Mag. (October 2000), pp. 161–167.
  8. G. Bernstein, E. Mannie, and V. Sharma, “Framework for MPLS-based control of optical SDH/SONET networks,” IEEE Netw. (July/August 2001), pp. 20–26.
  9. L. Berger, ed., “Generalized MPLS—signaling functional description,” Work in Progress, draft-ietf-mpls-generalized-signaling-09.txt (Internet Engineering Task Force, August 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-signaling-09.txt">http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-signaling-09.txt</a>.
  10. L. Berger, ed., “Generalized MPLS Signaling—RSVP-TE Extensions,” Work in Progress, draft-ietf-mpls-generalized-rsvp-te-09.txt (Internet Engineering Task Force, September 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-rsvp-te-09.txt">http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-rsvp-te-09.txt</a>.
  11. J. Duffy, “Intelligent services make MANs hot,” Network World (8 May 2000), <a href="http://www.nwfusion.com/news/20++00/0508infra1.html">http://www.nwfusion.com/news/2000/0508infra1.html</a> .
  12. K. Kompella and Y. Rekhter, eds., “OSPF extensions in support of generalized MPLS,” Work in Progress, draft-ietf-ospf-gmpls-extensions-09.txt (Internet Engineering Task Force, December 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-rsvp-te-09.txt">http://www.ietf.org/internet-drafts/draft-ietf-ccamp-ospf-gmpls-extensions-09.txt</a> .
  13. Nonpreemptible unprotected traffic, a feature commonly offered in more expensive and more complex 2F and 4F BLSR systems.
  14. P. Pan, D. H. Gan, G. Swallow, J. P. Vasseur, D. Cooper, A. Atlas, and M. Jork, “Fast reroute extensions to RSVP-TE for LSP tunnels”, Work in Progress, draft-ietf-mpls-rsvp-lsp-fastreroute-01.txt (Internet Engineering Task Force, November 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-rsvp-lsp-fastreroute-01.txt">http://www.ietf.org/internet-drafts/draft-ietf-mpls-rsvp-lsp-fastreroute-01.txt</a> .
  15. Y. Xu, P. N. Lamy, E. L. Varma, and R. Nagarajan “Generalized MPLS-based distributed control architecture for automatically switched transport networks,” Bell-Labs Tech. J. (January–June 2001), pp. 13–32.</
  16. We define a focal node on a UPSR ring to be a node that either originates or terminates a TDM LSP (or TDM channel/circuit) or one that sits at the intersection of two or more UPSR rings.

Bell-Labs Tech. J. (1)

Y. Xu, P. N. Lamy, E. L. Varma, and R. Nagarajan “Generalized MPLS-based distributed control architecture for automatically switched transport networks,” Bell-Labs Tech. J. (January–June 2001), pp. 13–32.</

IEEE Commun. Mag. (5)

G. Swallow, “MPLS advantages for traffic engineering,” IEEE Commun. Mag. (December 1999), pp. 54–57.

D. Awduche and Y. Rekhter, “Multiprotocol lambda switching: combining MPLS traffic engineering control with optical crossconnects,” IEEE Commun. Mag. (March 2001), pp. 111–116.

A. Bannerjee, J. Drake, J.P. Lang, B. Turner, D. Awduche, L. Berger, K. Kompella, and Y. Rekhter, "Generalized multi protocol label switching: an overview of signaling enhancements and recovery techniques,' IEEE Commun. Mag. (July 2001), pp. 144–151.

A. Banerjee, J. Drake, J. P. Lang, B. Turner, K. Kompella, and Y. Rekhter, “Generalized multi protocol label switching: an overview of routing and management enhancements,” IEEE Commun. Mag. (January 2001), pp. 144–150.

G. Bernstein, J. Yates, and D. Saha “IP-centric control and management of optical transport networks,” IEEE Commun. Mag. (October 2000), pp. 161–167.

IEEE Netw. (1)

G. Bernstein, E. Mannie, and V. Sharma, “Framework for MPLS-based control of optical SDH/SONET networks,” IEEE Netw. (July/August 2001), pp. 20–26.

Other (9)

L. Berger, ed., “Generalized MPLS—signaling functional description,” Work in Progress, draft-ietf-mpls-generalized-signaling-09.txt (Internet Engineering Task Force, August 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-signaling-09.txt">http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-signaling-09.txt</a>.

L. Berger, ed., “Generalized MPLS Signaling—RSVP-TE Extensions,” Work in Progress, draft-ietf-mpls-generalized-rsvp-te-09.txt (Internet Engineering Task Force, September 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-rsvp-te-09.txt">http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-rsvp-te-09.txt</a>.

J. Duffy, “Intelligent services make MANs hot,” Network World (8 May 2000), <a href="http://www.nwfusion.com/news/20++00/0508infra1.html">http://www.nwfusion.com/news/2000/0508infra1.html</a> .

K. Kompella and Y. Rekhter, eds., “OSPF extensions in support of generalized MPLS,” Work in Progress, draft-ietf-ospf-gmpls-extensions-09.txt (Internet Engineering Task Force, December 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-generalized-rsvp-te-09.txt">http://www.ietf.org/internet-drafts/draft-ietf-ccamp-ospf-gmpls-extensions-09.txt</a> .

Nonpreemptible unprotected traffic, a feature commonly offered in more expensive and more complex 2F and 4F BLSR systems.

P. Pan, D. H. Gan, G. Swallow, J. P. Vasseur, D. Cooper, A. Atlas, and M. Jork, “Fast reroute extensions to RSVP-TE for LSP tunnels”, Work in Progress, draft-ietf-mpls-rsvp-lsp-fastreroute-01.txt (Internet Engineering Task Force, November 2002), <a href="http://www.ietf.org/internet-drafts/draft-ietf-mpls-rsvp-lsp-fastreroute-01.txt">http://www.ietf.org/internet-drafts/draft-ietf-mpls-rsvp-lsp-fastreroute-01.txt</a> .

We define a focal node on a UPSR ring to be a node that either originates or terminates a TDM LSP (or TDM channel/circuit) or one that sits at the intersection of two or more UPSR rings.

GR-1400-CORE, “SONET dual-fed unidirectional path switched ring (UPSR) equipment generic criteria,” Issue 2 (Bellcore, January 1999), <a href="http://www.telcordia.com/">http://www.telcordia.com/</a>.

GR-1230-CORE, “SONET bi-directional line switched ring (BLSR) equipment generic criteria,” Issue 4 (Bellcore, December 1998), <a href="http://www.telcordia.com/">http://www.telcordia.com</a>.

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