Analyzing AS PATH in packets

[Alexander Zubkov]

Hi,

Yes, in version 2 the filter is applied before the prepend is made
during exporting. With tcpdump try to use "-s0 -v" options, it should
"decrypt" the bgp messages well.

On Tue, Aug 4, 2020 at 9:42 AM Julien Sansonnens <julien at jsansonnens.ch> wrote:
>
> Dear all,
>
> using bird 2.0.7
>
> I'm a bit confused with the output of "show route export". I'm exporting a full table to a downstream. I'm expecting to see my own AS as the first AS in AS PATH but it will not show in "BGP.as_path"
> If I prepend it, then it appears on the output.
>
> I don't know if it's related to display, or if my AS is really not added to the PATH. Perhaps it is added later in the process, before leaving my router ?
>
> How can I check this? I tried with "debug", but to my knowledge, it is not possible to display route details. I thought about doing tcpdump, but I haven't found out how to interpret the result correctly and see the AS PATH.
> Would you have a clue on how to see exactly what is being exported on an interface?
>
>  thanks a lot
> Julien
>