Multiple routing tables with multiple gateways

[Fernando Frediani]

Hello there,

I'm currently writing a project document which consists in a server to 
be hosted in a Internet Exchange Point, (similar to a route server but 
with another propose) and one of the things it must do is: When it 
receives a request coming from an IP range from ISP A it must go out to 
the internet using the ISP A gateway, when the request comes from ISP B 
IP range it goes out via that ISP router and so on. Any request 
originating on the server itself goes out via the Internet Exchange 
connectivity.

I know this can be done using IProute2 and creating multiple routing 
tables, but I would rather automate it using BIRD, so the ISPs would 
establish a BGP session to the server, announce their IP range, but in a 
different way they do with a Route server as they would need also to 
announce default route, and BIRD would take care to inform the kernel 
for when the request comes from those IPs it needs to use the specific 
ISP gateway for that.

Would anyone be able to point me to the right direction in terms of BIRD 
BGP config in order to achieve that, specially with regards the main 
differences to a Route Server.

Thanks
Best regards,

Fernando