Hi Arzhel, On Fri, Apr 12, 2024 at 11:57:38AM +0200, Arzhel Younsi wrote:
But for IPv6, it's cleaner to only require the router's link local address: testvm2006:~$ ip -6 addr inet6 2620:0:860:140:10:192:24:4/128 scope global testvm2006:~$ ip -6 route default via fe80::2022:22ff:fe22:2201 dev ens13 metric 1024 pref medium
In Bird: neighbor fe80::2022:22ff:fe22:2201%ens13 external;
But then the link local address doesn't work with multihop (for obvious reason). bird: /etc/bird/bird.conf:22:1 Multihop BGP cannot be used with link-local addresses
I use lladdrs for BGP endpoints in my network and that works fine. I think using `direct` instead of `multihop` in the v6-lladdr case would make it work for you. One word of advice: don't use the %scope syntax, use the `interface` directive instead. I don't recall exactly why but I had some subtle problem with that. As for your v4/32 problem, give `multihop 1` a try. That enforces no routers on the path to the peer like direct but allows off-subnet endpoints. Do keep in mind the docs recommend setting the source address explicitly when enabling multihop. multihop [number] Configure multihop BGP session to a neighbor that isn't directly connected. Accurately, this option should be used if the configured neighbor IP address does not match with any local network subnets. Such IP address have to be reachable through system routing table. The alternative is the direct option. For multihop BGP it is recommended to explicitly configure the source address to have it stable. Optional number argument can be used to specify the number of hops (used for TTL). Note that the number of networks (edges) in a path is counted; i.e., if two BGP speakers are separated by one router, the number of hops is 2. Default: enabled for iBGP. The reason why direct isn't working is also clear from the docs: direct Specify that the neighbor is directly connected. The IP address of the neighbor must be from a directly reachable IP range (i.e. associated with one of your router's interfaces), >>>otherwise the BGP session wouldn't start but it would wait for such interface to appear<<<. The alternative is the multihop option. Default: enabled for eBGP. Hope that helps, --Daniel