This reminds me of a failure mode I observed in OSPF. I don't know for certain if the same failure mode exists in BGP, but the symptoms sure look similar.
In OSPF the nodes connected to an Ethernet segment will elect a master. OSPF will verify that each node can communicate with the master, and this can be continuously verified with BFD.
OSPF will then assume that if two nodes can both communicate with the master, then they can also communicate directly with each other. If that assumption does not hold OSPF will configure routes which will always fail during the neighbor discovery step of the packet forwarding. I observed this behavior in two mainstream OSPF implementations.
Mythic Beasts (npub1wy5…64vc) Andrews & Arnold Ltd (AAISP) (npub1sv0…rq9x) Does the BGP implementation that you are using accept routes for which the advertised next hop does not respond to neighbor solicitation?
kasperd /
npub1jh…xut5y
2024-08-25 10:46:49
in reply to nevent1q…ya79
Author Public Key
npub1jhpgfu25y30c3h9xrrlxhrhge7669h3xwphjs99nau4k66ctsnyqjxut5yPublished at
2024-08-25 10:46:49Event JSON
{
"id": "3f5b857a1a5d2e287f2fdb9211dcabad626b8f514769c31324f36130d076cbb0",
"pubkey": "95c284f154245f88dca618fe6b8ee8cfb5a2de26706f2814b3ef2b6d6b0b84c8",
"created_at": 1724582809,
"kind": 1,
"tags": [
[
"p",
"831f088c53bea5a2faa06f0123cc9c1d30b816c1c4b1dbf0100a2cff8f612bb6"
],
[
"p",
"712913b00ac899746988cf9496deb3992caff8f7cc36a78527aaf319ab4f24d0"
],
[
"p",
"da50c965cdff34b1c8bd03920adf447dd35fadbeb8c1b63b53da77e5284e43dc"
],
[
"p",
"95c284f154245f88dca618fe6b8ee8cfb5a2de26706f2814b3ef2b6d6b0b84c8"
],
[
"e",
"861c2741776f5c59295d553869c9d3d7642d86a000b8587b76e807349f96ebe0",
"",
"reply",
"95c284f154245f88dca618fe6b8ee8cfb5a2de26706f2814b3ef2b6d6b0b84c8"
],
[
"e",
"fb89bd49960662422b8344475955a739973aae46574cd09ab776cde7840a7ede",
"",
"root",
"da50c965cdff34b1c8bd03920adf447dd35fadbeb8c1b63b53da77e5284e43dc"
],
[
"proxy",
"https://westergaard.social/objects/cac800d1-075b-4e2e-bf5f-da2851cf35b3",
"activitypub"
],
[
"L",
"pink.momostr"
],
[
"l",
"pink.momostr.activitypub:https://westergaard.social/objects/cac800d1-075b-4e2e-bf5f-da2851cf35b3",
"pink.momostr"
],
[
"-"
]
],
"content": "This reminds me of a failure mode I observed in OSPF. I don't know for certain if the same failure mode exists in BGP, but the symptoms sure look similar.\n\nIn OSPF the nodes connected to an Ethernet segment will elect a master. OSPF will verify that each node can communicate with the master, and this can be continuously verified with BFD.\n\nOSPF will then assume that if two nodes can both communicate with the master, then they can also communicate directly with each other. If that assumption does not hold OSPF will configure routes which will always fail during the neighbor discovery step of the packet forwarding. I observed this behavior in two mainstream OSPF implementations.\n\nnostr:npub1wy538vq2ezvhg6vge72fdh4nnyk2l78hesm20pf84te3n260yngqud64vc nostr:npub1sv0s3rznh6j6974qduqj8nyur5cts9kpcjcahuqspgk0lrmp9wmqnfrq9x Does the BGP implementation that you are using accept routes for which the advertised next hop does not respond to neighbor solicitation?",
"sig": "a9199321c600cb4b7dddb1f732edf81e7be9ebba295c3d8680acb3a38697a175afce76a0b54c490595d85790676fee67a85094f03639b8f323406269e34228bb"
}