Question about babel over bird

Juliusz Chroboczek jch at irif.fr
Thu Jan 12 16:48:12 CET 2023


> But this filter applies in the antenna that advertise the route.
> 10.20.2.2 and 10.20.2.36 advertise 10.0.0.0/8
> 
> 10.20.2.162 and 10.20.3.1 links with 10.20.2.2 and i want that 10.20.2.162 uses
> 10.20.2.36 (not direct link) for 10.0.0.0/8 not 10.20.2.2 and 10.20.3.1 uses
> 10.20.2.2

For anyone who's lost:

                 162
                /   \
               /     \
 Internet --- 2       36 --- Internet
               \     /
                \   /
                 3.1

Oriol wants 162 to reach the Internet through 36 and 3.1 to reach the
Internet through 2.

> So i need to modify in 10.20.2.162 and 10.20.3.1 the 10.0.0.0/8 gateway
> Is this possible with babel?

It's possible with babeld (the standalone implementation of Babel), which
allows filtering on router-id.  Toke will correct me if I'm wrong, but
I don't think that the BIRD implementation can do that.

Another solution would be to use source-specific routing, but that's only
supported for IPv6, not for IPv4.  (Older versions of babeld supported
source-specific routing for IPv4, but that was removed due to the complexity
of the code.)

-- Juliusz


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