Hi.

So, the Linux BGP routers perform packet forwarding. Up until this point they were handling only my own network/prefixes/traffic. Everything is using the default linux/bird main tables.

I want to provide connectivity to the customer. I would announce his prefix to a select few of my upstream eBGP sessions and also export some of the upstream routes to him.

So, at the very least I need a separate routing table (on linux) to have a different FIB for my own traffic and the customer's.

But since I want to export some routes to the customer (and not just a default route) I need a way to be able to hand off him the raw upstream routes that I receive via eBGP. When I receive upstream routes I process them with filters (some get rejected, some I set a different local preference, etc. in the end they are modified to suit my use cases).

So this is what I am asking: does it make sense to have a separate bird table per each upstream eBGP session so that I can keep the raw routes there, and eventually feed them via the pipe protocol to my own routing table for processing, and to the customer's table?

Hope this makes sense.

Thanks.

wt., 19 mar 2024 o 23:34 Alexander Zubkov <green@qrator.net> napisał(a):

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@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!
>
>
>
>