Difference between loopback and dummy interfaces for use in Linux routing

Wilhelm Schuster ws at rot13.io
Fri Apr 27 22:42:23 CEST 2018


On 2018-04-27 21:47, Maximilian Wilhelm wrote:
> This way it's easy to have different direct protocols in bird and
> easily tag, filter and/or announce prefixes within your network
> accordingly. real loopback IPs are part of the IGP (OSPF), both 2 and
> 3 are read by instances of protocol direct and distributed by (i)BGP.

I didn't consider that, but it looks like an interesting approach.
Reading the bird documentation, it slightly discourages from using the
direct protocol:

> The question is whether it is a good idea to have such device routes
> in BIRD routing table. OS kernel usually handles device routes for
> directly connected networks by itself so we don't need (and don't want)
> to export these routes to the kernel protocol. OSPF protocol creates
> device routes for its interfaces itself and BGP protocol is usually used
> for exporting aggregate routes. But the Direct protocol is necessary for
> distance-vector protocols like RIP or Babel to announce local networks.

Though, I'll definitely be trying it out.

Cheers, Wilhelm.


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