From: alsontra@hotmail.com
Date: Fri Feb 20 2004 - 00:24:46 GMT-3
Hello Robert,
The short answer to your question is, it depends. It depends on the link and
network type or how you've configured the protocol.
<snip - RFC 2328 Protocol Packet Processing section 8.>
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.
Retransmissions of Link State Update packets are ALWAYS sent
directly to the neighbor. On multi-access networks, this means
that retransmissions should be sent to the neighbor's IP
address.
The IP source address should be set to the IP address of the
sending interface. Interfaces to unnumbered point-to-point
networks have no associated IP address. On these interfaces,
the IP source should be set to any of the other IP addresses
belonging to the router. For this reason, there must be at
least one IP address assigned to the router.[2] Note that, for
most purposes, virtual links act precisely the same as
unnumbered point-to-point networks. However, each virtual link
does have an IP interface address (discovered during the routing
table build process) which is used as the IP source when sending
packets over the virtual link.
</snip>
----- Original Message -----
From: "McCallum, Robert" <robert.mccallum@thus.net>
To: <ccielab@groupstudy.com>
Sent: Thursday, February 19, 2004 1:37 PM
Subject: OSPF question Database Exchange Process
> During the Database Exchange Process on a broadcast network are the
packets between the master and the slave unicast or mulitcast packets? We
cant seem to find any decent document which actually talks about the
Database Exchange Process in better detail.
>
> TIA
>
> Robert McCallum
> CCIE #8757 R&S
>
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