From: sheherezada@gmail.com
Date: Fri May 23 2008 - 15:43:50 ART
If you receive default from both providers, you are still connected to
the outside world if the link to ISP1 is lost. However, you have some
things to configure beforehand, if you want ISP2 to act only as a
backup (and avoid asymmetrical routing):
(1) give a higher preference to the default from ISP1, if you want to
follow the path from ISP1 only (during normal operation)
(2) prepend your AS (say twice) when announcing your route to ISP2, if
you want to discourage download through ISP2 (during normal operation)
Make sure to announce only your route to both providers (configure a
prefix list).
BTW, receiving partial routes from ISP1 does not make sense is this is
your primary provider. This would make sense if you prefer ISP1 for
local (say metropolitan) upload and ISP2 for the other destinations,
during normal operation.
If you want HSRP to track the gateway to ISP1, you could use IP SLA...
HTH,
Mihai Dumitru
On Thu, May 22, 2008 at 4:43 PM, Ashwani <ash_r135@hotmail.com> wrote:
> Hello,
>
> BGP multihoming scenario if we are getting only partial routes & default
> route from ISP1 & default only from ISP2.
>
> Internet
> | |
> (Primary)ISP1 ISP2(Backup)
> | |
> EBGP | |EBGP
> R1ibgpR2
> .1 | | .2
> __________HSRP(.3)______________192.168.1.0/24 (Advertising this subnet)
>
> If we loose connection with ISP1 , will traffic will take path from R2
> automatically? or do I need to change default route under R1 to point
> towards ISP2 ??
> I never worked on BGP so any help will be appreciated or any examples.
>
> Thanks,
> Ashwani
>
>
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