OSPF Non-Broadcast Network Type over Frame-Relay

[lagapidis (Lazarus Agapidis)]

Hello Narad

@narad

@lagapidis you said that the point to multipoint network types is a collection of point to point thats right…but you said that there can a different subnet of each point to point connection …How ??

Yes, I mention that in this post. The statement was made not in relation to the subnets being used, but in relation to the fact that there are no DR/BDR elections. I have updated the text of the post for clarification.

@narad

Frame relay and ATM and DMVPN,GRE , Over these overlay VPN we cant communicate between the OSPF neighbors by using multicast address 224.0.0.5…Right ??

Frame relay and ATM don’t support multicast natively, however, they can be made to support it in a pseudomulticast manner. As Rene mentioned in this post for Frame Relay, it is an NBMA technology, but with the correct frame-relay maps, you can “emulate” broadcast traffic.

DMVPN and GRE however are technologies that natively support multicast, so OSPF is able to operate over these networks. You can see in the lesson describing DMVPN Phase 1 with OSPF that the broadcast network type works well with DMVPN, as is the case with Phase 2 and Phase 3. DMVPN is based on GRE technology, so both similarly support multicast, thus, they support OSPF neighbors using the multicast address for communication.

I hope this has been helpful!

Laz