Re: BGP IPv4

From: Petr Lapukhov (petr@internetworkexpert.com)
Date: Wed Jul 16 2008 - 03:55:10 ART

Hi,
In your case, if the customer is using the same public AS number on both
sites, you may use the "allowas-in" BGP feature.
This per-neighbor command allows a BGP speaker to accept updates with it's
own AS number in AS_PATH attribute. Configure this feature on your
customer's BGP peering sessions with their respective ISPs.

==

router bgp 100
neighbor x.x.x.x allowas-in <count>

==

Adjust the <count> value to match the number of AS num repetitions you want
to accept (e.g. this needed if some of the sites is doing AS_PATH
prepending)

Obviously, you need to ensure the segmeted regions do not advertise the same
prefixes to their ISPs, e.g. have non-overlapping addressing spaces. Also,
allowing to accept your own AS number may potentially lead to routing loops,
so be careful when implementing your filtering policy.

HTH 

-- 
Petr Lapukhov, CCIE #16379 (R&S/Security/SP/Voice)
petr@internetworkexpert.com

Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Outside US: 775-826-4344
Online Community: http://www.IEOC.com
CCIE Blog: http://blog.internetworkexpert.com

2008/7/16 Harindha Fernando <pottaharry@gmail.com>:

>  Hi Experts,
>
> I need your feedback for the below BGP IPv4 (NO MPLS) scenario.
>
> CUSTOMER (AS 100) <--> SERVICE_PROVIDER(AS 200) <---> INTERNET
> <---->CUSTOMER(AS 100)
>
> This particular customer needs to use the SAME AS(100)  in two different
> parts of the world.
>
> 1. Can this be done ?
> 2. If yes, how ?
> 3. if no, why ?
>
> Your earliest response is highly appreciable.
>
> Rgds,
> Harin.
>
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

This archive was generated by hypermail 2.1.4 : Mon Aug 04 2008 - 06:11:55 ART