Subject: BGP on Ethernet

From: "Mareline Sheldon" <[email-masked]>
Date: Tue, 4 Dec 2001 18:24:58 +0530

Hi!
Can anybody give me some information/help as to what all changes are to be
incorporated into BGP when migrating it from a single processor environment
to a multi processor distributed architecture.Let me be a little more
articulate. In a multiprocessor distributed architecture we have different
processors (probably shacked up in different shelves) running the routing
protocols. We need to keep the routing tables synched up in all these
processors. One idea is to connect all these routers (processors) within the
router to form a complete IBGP mesh. But then this introduces scalability
issues which everyone is well aware of. What is the other alternative that
we have to keep all these routing engines synchronized.

regards,
mareline s.

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From: "John Stracke" <[email-masked]>
Date: Tue, 4 Dec 2001 10:16:34 -0500

>We need to keep the routing tables synched up in all these

Well...fundamentally, I'm not sure you have much in the way of 
alternatives.  You could use a different synchronization protocol; but the 
scaling issues are likely to be the same as with BGP.  (I'm assuming here 
that you're not planning on exposing the N processors to the outside BGP 
world separately.) Either way, you're passing messages around which update 
the routing table.

One option would be a client/server system, where the clients forward all 
incoming BGP updates to the server, and the server maintains the routing 
table.  This could work if you can devise a server-to-client protocol that 
the clients can interpret more cheaply than they interpet BGP.  (The 
simplest way to do that, of course, is if all the processors are in a 
single box, and the clients can read the routing table directly out of 
memory.) This has the disadvantage of introducing a single point of 
failure.

/==============================================================\
|John Stracke                   |Principal Engineer            |
[email-masked]  |Incentive Systems, Inc.       |
|http://www.incentivesystems.com|My opinions are my own.       |
|==============================================================|
|"Simply vanished--like an old oak table." --Lord Percy, _Black|
|Adder II_                                                     |
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