BGP Session via Wireguard and IPv6 LL

General questions
1

Hi there,
I’m trying to peer on dn42 using ipv6 link local addresses. As multiple of my peers use the same address of fe80::ade0 I can not use set protocols bgp neighbor fe80::ade0 as I would need to state it multiple times and the it does not accept an interface identifier.

So I use the following configuration:
Wireguard:

 wireguard wg4242423914 {
     address fe80::ade1/64
     ipv6 {
         address {
             no-default-link-local
         }
     }
     peer to-de2 {
         address 116.203.141.239
         allowed-ips fe80::ade0/128
         persistent-keepalive 25
         port 21486
         public-key xxx
     }
     private-key yyy
 }

BGP:

 address-family {
     ipv6-unicast {
         network fdd0:45b1:4cdf::/48 {
         }
     }
 }
 neighbor wg4242423914 {
     address-family {
         ipv6-unicast {
         }
     }
     interface {
         v6only {
             remote-as 4242423914
         }
     }
     update-source wg4242423914
 }
 parameters {
     router-id 192.168.221.22
 }
 system-as 4242421486

With this my neighbor neve exits Idle state as frr seems to not know which address to connect to. At the same time i can see all node ndp request with no replies and connection attempts from my peer. Does someone know how I can proceed?

Edit: I noticed I included secrets in the config dump. Keys hav been rotated and censored.

2

I digged a bit further and found that my bgp config works when going via a normal ethernet link. So the issue seems to be somewhere in my wireguard setup. As of now it seems that IPv6 multicast does not travel across the wireguard tunnel even when allowing ff00::/10 . I will need to look further there.

3

Have a look at Issues with MP-BGP and IPv6 Link-local peers using extended next-hop - #2 by zero1three013, there is a reference configuration for Wireguard + BGP for extended next hop + IPv6 link local on DN42

4

Thanks, but this thread does not address the issue I have. If I specify the link local address directly as neighbor it works. The issue is I have two neighbors that use the same IPv6 link local address and I can not specify fe80::ade0%wgx as a neighbor to differentiate them. I could use auto discovery and set the interface as a neighbor but then I need IPv6 Multicast traffic to traverse the wireguard tunnel to discover the neighbor but this does not work.