MPLS Optimized Multipath (MPLS--OMP)

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as \work in progress." This draft speciies a precedure for routing MPLS label switched paths and balancing load across these paths. The algorithms presented here have been coded into a simulator and performance has been evaluated for a limited set of cases. Some details of the algorithms are likely to change as simulations progress. The portions of this document for which simulation experience is limited are Section 6, Section 7, Appendix B.7. This draft contains notes pointing out sections which are more likely to change. Abstract MPLS ingress routers may establish one or more explicit paths to a given egress to the MPLS domain. Load can be balanced across a complex topology using MPLS and the technique referred to here as MPLS{OMP (Multiprotocol Label Switching { Optimized Multipath). The technique requires the use of a link state interior gateway protocol (IGP) such as OSPF or IS{IS with extensions to the link state protocol to ood loading information. It requires the ingress router be capable of computing a hash with a suuciently ne level of granularity based on the IP source and destination and selecting a forwarding entry based on the outcome of the hash. MPLS Optimized Mulitpath is an extension to MPLS. MPLS-OMP requires no additions or modii-cation to the MPLS protocols. MPLS-OMP does require that the IGP be capable of ooding loading information as described in the OSPF-OMP and ISIS-OMP documents. At the MPLS ingress an algorithm is applied to select alternate paths where needed and adjust forwarding. Forwarding is adjusted gradually enough to insure stability yet fast enough to track long term changes in loading. The load adjustment algorithm itself is fully deened in a related document describing OSPF{OMP. The application of this technique to MPLS is described here. 1 Overview Networks are often heavily loaded. Topologies often evolve to include multiple paths. Multiple paths may be initially designed to provide redundancy but also result from incremental addition of circuits to accommodate traac growth. The redundant paths provide a potential to …