Routing Multipoint Relay Optimization for the Optimized Link State Routing Protocol Version 2 (OLSRv2)
updates
- rfc-7181 — The Optimized Link State Routing Protocol Version 2
Extracted elements (6)
RFC 7185 documented the rationale for using link metrics in OLSRv2 and indicated that the original routing MPR selection requirement in RFC 7181 was overly prescriptive, motivating this update to permit the optimization.
The optimization is purely permissive — it allows removal of unnecessarily selected routing MPRs without requiring any implementation to include it. It can create smaller and fewer TC messages without ever having the opposite effect.
Implementations that do and do not implement this routing MPR optimization will interoperate seamlessly, as the optimization introduces no new protocol signals and does not change processing of received signals.
A set of routing MPRs created as specified in RFC 7181 MAY be optimized by removing routers from the routing MPR set when a shorter cumulative path exists through other N1 elements.
The routing MPR optimization checks for a sequence x_0, ..., x_n of N1 elements where d1(x_0) + d2(x_0,y_1) + ... + d2(x_m-1,y_m) < d1(x_m), allowing x_1 through x_n to be removed from the routing MPR set if selected.
This update introduces no new protocol signals and does not change processing of any received protocol signals. Eliminating unneeded routers from routing MPR sets also eliminates corresponding TC message information that was unused anyway, so no additional security considerations arise beyond those in RFC 7181.