OSPF in NBMA

Apr 27, 2005 4 Replies

Two offices have to be connected together via an NBMA frame relay connection, and running OSPF across this network. What kind of configuration structure should be used?



A. Point-to-point over sub-interfaces.



B. Point-to-multipoint star configuration.



C. None of the above.



My answer: A cause using point to point subinterfaces will eliminate the issues surrounding split horizons over NBMA networks.



What do you guys think?


Point to point sub-interfaces are generally favored to allow for flexibility in maintaining the configurations going forward. Split-horizon is not an issue for OSPF, but may be an issue for other routing protocols that may also share the physical interface at some point.

FWIW, Robert

I'll go with A.

Split-horizon is not an issue for OSPF, but may be an issue for distance vector (including EIGRP) routing protocols that may also share the physical interface at some point.

Since there are just 2 sites connected to each other via NBMA frame-relay and no requirement for one to be a multipoint hub, point to point sub-interfaces are generally favored to allow for flexibility in maintaining the configuration.

FWIW, Robert

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