Re: BGP peculiarity

Amit,

When an e-bgp neighbor advertises a prefix to you, it will prepend its AS
number, and if you ever advertise it back to him, he will see his AS number
in the update and reject the route. Unless you have "AS-OVERRIDE" or he has
"ALLOWAS-IN".

On Fri, Sep 16, 2011 at 5:09 AM, Amit Kumar Lohumi <getakl_at_gmail.com> wrote:

> Hi All,
>
> Can anyone pls explain ....
>
> why is it that in some cases a BGP router would not advertise e-BGP
> routes learned from a peer back to the same peer (sticking to the
> standard rule on BGP updates).
>
> ... while in other cases, BGP will infact advertise the e-BGP routes
> learned from a peer back to the same peer (although they do get
> rejected by the originating peer because of ASN match ).
>
> I have made these dichotomous BGP observations on a couple of
> different scenarios.
>
> Regards
>
>
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