Subject: Re: How Many Routing Tables

From: [email-masked]
Date: Thu, 23 Mar 2000 20:03:37 +0100

Hy David - It depends!
If you're redistributing RIP into OSPF, and  into BGP, fine.
If not, I don't see what you're doing. You'll have one for every protocol.
Assuming it is a Cisco router, the router will have a BGP table (build on
BGP messages), a OSPF table with the redistributed RIP routes and the OSPF
entries. Note that the router needs to be redistributing in order that OSPF
understands RIP messages. Every routing protocol (RIP being vector, OSPF
being link state) has it's own "language", way of exchanging information.
This info is carried in the fields in the packets. An OSPF packet doesn't
equal a RIP packet. Thus also the database will be different. Besides the
algorithm is not the same.
RIP defines 2 message types: Request and Response. "Uses a routing
algorithm in which routers periodically send routing updates to all
neighbours by broadcasting their entire route tables. Next hop information
relevant for routing.
OSPF has link state advertisements that it put's into the topology
database. When database is synchronised with neighbour, only changes will
be sent. Metric cost relevant for routing.

I hope this helps

Sincerly,

Damjan
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From: Nguyen Tuong Long Le <[email-masked]>
Date: Tue, 28 Mar 2000 11:05:28 +0200

Just as a follow-up question: Can somebody tell me how many route entries there
are in edge and core routers nowadays?

Thanks,
-- long