RIB showing unspecified next-hops when only link-local hop is provided by neighbour

[TimVosch]

Hi,

I'll preface this by saying I do not have advanced knowledge about BGP specs.

I am running on DN42, my peer is using BIRD, and I am running an IPv6 only stack. My gobgp shows an established connection with 900+ accepted routes. The peer provides me with the following output for troubleshooting:

BIRD Details running on peer

Name       Proto      Table      State  Since         Info
AS4242420700_v4 BGP        ---        start  2025-10-26 11:06:58  Connect       
  BGP state:          Connect
    Neighbor address: 192.168.222.127
    Neighbor AS:      4242420700
    Local AS:         4242423914
  Channel ipv4
    State:          DOWN
    Table:          t_bgp_v4
    Preference:     100
    Input filter:   (unnamed)
    Output filter:  (unnamed)
    Import limit:   5000
      Action:       block
Name       Proto      Table      State  Since         Info
AS4242420700_v6 BGP        ---        up     2025-10-26 23:08:31  Established

BGP state:          Established
Neighbor address: fe80::ade1%4242420700
Neighbor AS:      4242420700
Local AS:         4242423914
Neighbor ID:      10.188.100.10
Local capabilities
Multiprotocol
AF announced: ipv6
Route refresh
Graceful restart
4-octet AS numbers
Enhanced refresh
Long-lived graceful restart
Neighbor capabilities
Multiprotocol
AF announced: ipv6
Route refresh
4-octet AS numbers
Hostname: ENTRY
Session:          external AS4
Source address:   fe80::ade0
Hold timer:       77.333/90
Keepalive timer:  0.746/30
Send hold timer:  160.370/180
Channel ipv6
State:          UP
Table:          t_bgp_v6
Preference:     100
Input filter:   (unnamed)
Output filter:  (unnamed)
Import limit:   5000
Action:       block
Routes:         0 imported, 926 exported, 0 preferred
Route change stats:     received   rejected   filtered    ignored   accepted
Import updates:              0          0          0          0          0
Import withdraws:            0          0        ---          0          0
Export updates:          27429         12          0        ---      27417
Export withdraws:          473        ---        ---        ---        473
BGP Next hop:   :: fe80::ade0

Note the BGP Next Hop is set at :: and fe80::ade0. The peer's link-local address is fe80::ade0, mine is fe80::ade1.

GoBGP shows all routes having :: as next-hop. And zebra shows all routes as inactive with the same unspecified next-hop. Is GoBGP supposed to pickup the unspecified address only? Is this a CLI issue where it only shows the global next-hop? Though zebra also shows only the unspecified next-hop.

Would love to hear some ideas on this.

Sincerely, Tim van Osch.