Investigate IS-IS as routing protocol

[LeeSmet]

One of the main advantages is that it has a built-in 2 layer hierarchy, where there is a difference between backbone (l2) routers and local routers. For our use case we also might be able to add extra levels (to be investigated).

Mainly we should focus on the scalability aspect of using IS-IS vs Babel, since Babel has been shown not to scale very efficiently, at least in our setup

[delandtj]

yes... IS-IS is basically the base for BGP too but ISS-IS has openness to custom tlv's built-in (BGP being a standard would be too rigid)
also , there is already a full Rust implementation for it
https://github.com/holo-routing/holo/tree/master/holo-isis