Hi,
I would like to know the reason why the DBD packet in OSPF has the option field. The hello packet already has the options feild,so neighbour will be knowing of the supported options.
The reason mentioned in Jeff doyle is -----
When used in Hello packets, the Options field allows a router to reject a neighbor because of a capability mismatch. Alternatively, when capabilities are exchanged in Database Description packets a router can choose not to forward certain link state advertisements to a neighbor because of its reduced functionality. Lastly, listing capabilities in link state advertisements allows routers to route traffic around reduced functionality routers, by excluding them from parts of the routing table calculation.
When does this functionality come in to use. Please explain
