Subject: TCP on Ethernet:[Re:] BGP on Ethernet

From: "Mareline Sheldon" <[email-masked]>
Date: Wed, 5 Dec 2001 09:17:12 +0530

No the processors are not going to be exposed to the outside world. From
outside it'll be one single router. You yourself acknowledge the problems in
client-server architecture.
My intention is to let all other routers on my private LAN (inside my
router) know of all the routing updates each of my processor gets.

This is my idea, i dont know feasible it actually is:

As soon as one router recieves an update from the outside world it simply
broadcasts it within the router. Mind you we are talking of the BGP packets
(in effect TCP). Now my doubt is that each router will receive that
broadcast packet. But how to get it up the TCP stack to port 179. TCP
doesn't support broadcast/multicast so how do i do that !?!?

What changes do i need to bring in to the BGP protocol so that it may accept
broadcast packets also from its virtual interfaces i.e ones within the
router.

Can i do some sort of broadcasting/multicasting of TCP packets on an
ethernet.

regards,
mareline s.

John wrote:

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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---

From: Fred Baker <[email-masked]>
Date: Wed, 05 Dec 2001 06:39:46 -0800

At 07:47 PM 12/4/2001, Mareline Sheldon wrote:
>But how to get it up the TCP stack to port 179.

since this is your own little world, you don't have to use the same 
transport. Use reliable multicast in some form. An example of such recently 
went to Proposed Standard:

           "PGM Reliable Transport Protocol", 09/19/2001,
           <draft-speakman-pgm-spec-07.txt>

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Fri, 07 Dec 2001 08:45:04 -0800

thoughts....

1) one and only one of your boxes will send the TCP ACK on the
BGP session for incoming packets. this argues for keeping the
replication mechanism well away from the incoming BGP session.
2) if your boxes have much higher bandwidth between them than to
the external world, letting one compute the routing table and
the others snapshot it at intervals may be a better strategy than
running a distributed routing computation across the internal net.
3) same argument if the limiting factor is the CPU power
4) if internal comm is slow, and cpus fast, ibgp may be the
right approach. (but that would seem strange)

Lots of ideas, most of them irrelevant to the config you are running, 
probably....

          Harald

--On 5. desember 2001 09:17 +0530 Mareline Sheldon <[email-masked]> 
wrote:

> outside it'll be one single router. You yourself acknowledge the problems
> in client-server architecture.
> broadcasts it within the router. Mind you we are talking of the BGP
> packets (in effect TCP). Now my doubt is that each router will receive
> that broadcast packet. But how to get it up the TCP stack to port 179. TCP
> What changes do i need to bring in to the BGP protocol so that it may
> accept broadcast packets also from its virtual interfaces i.e ones within
> the router.
>
>| 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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