How to avoid /32 bit route in OSPF

abbas.ali · ‎05-13-2003

In OSPF (Frame-Relay Topology network type point-multipoint), router inserts /32 routes. Is it possible to avoid it? "NO PEER NEIGHBOR ROUTE" can only be used with PPP encapsulation so it won't work with default HDLC.

ives.dekoninck · ‎05-13-2003

This is normal behaviour for OSPF in point-to-multipoint networks! In fact it injects the /32 route to make it possible for a not fully meshed network to communicate.

If eg. you have a 3 routers connected like this

R1 --- R2 --- R3 and R2 uses a multipoint interface to connect then this means we will have eg a /29 on that interface. With R1 having .1 address, R2 .2 and R3 .3.

If we would use broadcast or none broadcast mode you will only see the /29 network in the routing table, so every router thinks the network is directly connected.

If R1 does not get a /32 route for the R3 router indicating it should go via R2 the routing won't work.

Yes, it is only through when R1 does not have a direct frame-relay map to R3 (though then we would create a full mesh).

If you don't want this /32 networks make the network broadcast mode though it will not be guranteed that the routing is still working.

Hope This helps,

-Ives-