3. Remote Loop Free Alternate (RLFA)
3.1 Solution
The Fast ReRoute "Remote Loop Free Alternate" (Remote LFA) solution is an extension of LFA. RLFA is specified in RFC 7490 [ IETF 7490 ]. RLFA is similar to LFA, except that the backup next-hop is not necessarily directly connected to the PLR by a physical link, but can be remote and joined by a virtual, tunnel-type link. In this case, RLFA uses an IP or MPLS tunnel to send its packets directly to this RLFA node.
Figure 8 illustrates a ring topology for which LFA cannot find a solution. RLFA finds a solution when the metrics of the links in the ring are close enough. Router "S" uses a tunnel (in blue)...
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Remote Loop Free Alternate (RLFA)
Preferences between several backup next-hops
Bibliography
- (1) - FRANCOIS (P.), FILSFILS (C.), EVANS (J.), BONAVENTURE (O.) - Achieving sub-second IGP convergence in large IP networks. - ACM SIGCOMM Computer Communication Review, vol. 35, issue. 3, pp. 35-44, DOI : 10.1145/1070873.1070877 (2005).
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Standards and norms
- IETF OSPF Version 2. - IETF RFC 2328 - 1998
- IETF LDP Specification. - IETF RFC 5036 - 2007
- IETF Basic Specification for IP Fast Reroute : Loop-Free Alternates. - IETF RFC 5286 - 2008
- IETF IP Fast Reroute Framework. - IETF RFC 5714 - 2010
- IETF Loop-Free Alternate (LFA) Applicability in Service Provider (SP) Networks. - IETF RFC 6571 - 2012
- IETF Remote Loop-Free Alternate (LFA)...
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