[isp-bgp] Re: EBGP and loopbacks

[Dean Anderson <dean@...>]

On Fri, 14 May 2004, ISP-BGP Discussion List digest wrote:

> ISP-BGP Digest for Thursday, May 13, 2004.
> Subject: EBGP and loopbacks
> From: Tulip Rasputin <tulip_rasputin@yahoo.ca>
> Date: Thu, 13 May 2004 07:19:33 -0400 (EDT)
> X-Message-Number: 1
> 
> Folks,
> 
> Does anyone here run EBGP on loopbacks?  I have this customer who wants to run EBGP using
> loopbacks. Dont we always use loopbacks with only the IBGP peering?
> 
> Regards,
> Rasputin

Absolutely. We __only__ run bgp on loopbacks. Otherwise, 1) your BGP
addresses are publicly visible, and 2) a momentary failure of the link
will bring down the BGP session (if this is desired, there are BGP levers
to do this).  Generally, you want to have the BGP timeout somewhere more
than 1 millisecond and somewhere less than the TCP timeout.  Indeed, you
probably want it more like 10 or 15 seconds--not too fast, not too slow.

If you have multiple physical paths to your peer, you want the backup link
to be used without interrupting the BGP session.  This is done simply with
multiple static routes through interfaces, which go away if the interface
is down.

All you have to do is create the loopbacks, and then set the source 
interface command on your bgp neighbor statements.  And tell your peers, 
of course, what address to use.

		--Dean







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