Chuck,
Radcom? CCO? How about checking the source, RFC 2328? ;-) It's all in
there.
From section 8.1, "Sending protocol packets:"
"The IP destination address for the packet is selected as follows. On
physical point-to-point networks, the IP destination is always set to the
address AllSPFRouters. On all other network types (including virtual
links), the majority of OSPF packets are sent as unicasts, i.e., sent
directly to the other end of the adjacency. In this case, the IP
destination is just the Neighbor IP address associated with the other end
of the adjacency (see Section 10). The only packets not sent as unicasts
are on broadcast networks; on these networks Hello packets are sent to
the multicast destination AllSPFRouters, the Designated Router and its
Backup send both Link State Update Packets and Link State Acknowledgment
Packets to the multicast address AllSPFRouters, while all other routers
send both their Link State Update and Link State Acknowledgment Packets to
the multicast address AllDRouters."
The path to the RouterID of the opposite virtual link endpoint is easy to
find. Think about the information contained in the link-state
database. Both endpoint routers are members of a single transit area, so
both routers have complete knowledge of the area topology and which
networks each router (known by RouterID identifying its Type 1 LSA) is
attached to. That's how they are able to draw their shortest-path trees,
after all.
Chuck, I hope you have some relaxing activities planned with your family
for today . . . it sounds to me as though you need a rest from CCIE studies
+ email!
Happy Independence Day to all, from our Nation's Capital!
Pamela
At 08:53 PM 7/3/01 -0400, Chuck Larrieu wrote:
>not the LSA, but the IP header itself.
>
>in general, the OSPF hello would be sent with a destination address of
>224.0.0.5, and would cross one hop, to the next router on the link.
>
>for a virtual link packet, being as the DA might be several hops away, what
>does the actual IP packet look like? Is the DA the IP of the other end of
>the virtual link?
>
>Cisco uses the RID, which may or may not be an actual in use IP address.
>
>Anyone ever sniffed virtual link packets and examined the construction?
>Can't find any examples in any of a number of sources I have checked,
>including CCO and Radcom.
>
>thanks
>
>Chuck
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=10978&t=10929
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