Adding a downstream ebgp connection. How to keep it separate?

[Alexander Zubkov]

Hi,

I think you need to start with explaining why do you want to keep
customer and upstream routes in separate tables.

Regards,
Alexander

On Tue, Mar 19, 2024 at 1:39 PM LU <zyash911 at gmail.com> wrote:
>
> Hello.
>
> I have two BGP routers with bird 2.4. Each router maintains some eBGP connections to upstreams where I announce my prefixes. These routers have an iBGP connection between themselves to exchange routes learned from those eBGP connections.
>
> I do some filtering on the eBGP connections (like setting local preference, as path prepending, setting an internal bgp community so that I know which routes originate from which eBGP connection, etc.)
>
> So far this is simple, works great for my own traffic/prefixes and have no trouble maintaining this.
>
> But now a need arose that I will be adding a downstream eBGP connection (customer). This means transiting a foreign prefix over my BGP routers and exporting some routes to it.
>
> How do I approach this the cleanest and simplest way possible?
>
> I suppose I should have two routing tables (currently under Linux/Bird everything is under the default routing/main table):
>
> - main table (keep for my own traffic)
> - customer table
>
> But I am unsure what to do with my existing upstream eBGP connections since I do some filtering on them for my own use cases.
>
> Should I have a separate Bird table for each upstream eBGP connection? Then use the pipe protocol to put the routes in the main and customer table separately?
>
> Then I could place the current filtering of eBGP connections that I use for myself in the pipe protocol that feeds my main table?
>
> The customer table will then be piped the raw routes from the eBGP connections.
>
> Is my thinking correct? Or this can be done better/differently?
>
> Are there perhaps any presentations and/or sample configs of such setups? I am sure this situation comes up quite often.
>
> Thanks!
>
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