Feb 8 04:52:48 er1.511.msp bfdd[31763]: BFDD_STATE_UP_TO_DOWN: BFD Session 2001:504:27::d1af:0:2 (IFL 360) state Up -> Down LD/RD(228/3270602753) Up time:16:39:29 Local diag: CtlExpire Remote diag: None Reason: Detect Timer Expiry.

Feb 8 04:52:48 er1.511.msp bfdd[31763]: BFDD_TRAP_SHOP_STATE_DOWN: local discriminator: 228, new state: down, interface: et-0/0/1.0, peer addr: 2001:504:27::d1af:0:2

Feb 8 04:59:05 er1.511.msp bfdd[31763]: BFDD_TRAP_SHOP_STATE_UP: local discriminator: 228, new state: up, interface: et-0/0/1.0, peer addr: 2001:504:27::d1af:0:2

Feb 8 05:12:26 er1.511.msp bfdd[31763]: BFDD_STATE_UP_TO_DOWN: BFD Session 2001:504:27::d1af:0:2 (IFL 360) state Up -> Down LD/RD(228/1591314386) Up time:00:13:22 Local diag: NbrSignal Remote diag: CtlExpire Reason: Received DOWN from PEER.

Feb 8 05:12:26 er1.511.msp bfdd[31763]: BFDD_TRAP_SHOP_STATE_DOWN: local discriminator: 228, new state: down, interface: et-0/0/1.0, peer addr: 2001:504:27::d1af:0:2

We saw BFD go down to rs2 when those updates took place an hour ago and hasn’t come back up, still down.

Juniper here, but based on ARP/ND for the others, looks like a mix of Cisco/Juniper devices so perhaps not specific to any platform.

Address State Interface Time Interval Multiplier

2001:504:27::d1af:0:2 Down et-0/0/1.0 3.000 2.000 3

Client BGP, TX interval 0.500, RX interval 0.500

Session down time 01:11:17, previous up time 00:13:22

Local diagnostic NbrSignal, remote diagnostic CtlExpire

Remote state Down, version 1

Session type: Single hop BFD

Min async interval 0.500, min slow interval 2.000

Adaptive async TX interval 2.000, RX interval 2.000

Local min TX interval 2.000, minimum RX interval 0.500, multiplier 3

Remote min TX interval 1.000, min RX interval 0.500, multiplier 3

Local discriminator 228, remote discriminator 1591314386

Echo TX interval 2.000, echo detection interval 6.000

Echo mode disabled/inactiveno-absorb, no-refresh

Session ID: 0x0

On Feb 8, 2024, at 00:01, Richard Laager <[log in to unmask]> wrote:

BIRD is complaining that various peers are sending BFD packets with an unknown session id.

Anyone have thoughts on this?

The logs look like this:
2024-02-07 23:44:14 <RMT> bfd1: Bad packet from YOUR_IP - unknown session id (SOME_INTEGER)

Those marked with an asterisk were doing this yesterday, so prior to the reboot of rs2.

rs1:

Inteliquent (Neutral Tandem)
206.108.255.137 *

rs2:

les.net
2001:504:27::4813:0:1

Savage Communications
206.108.255.17 *
2001:504:27::5adc:0:1 *

Stellar Association
206.108.255.53
2001:504:27::8e16:0:1 *

Hoyos Consulting
2001:504:27::d15d:0:1

Eastern Iowa Data Group
206.108.255.168 *
2001:504:27::f7a2:0:1 *

Omnitel Communications
206.108.255.148

Here is for the entire month of January:

rlaager@rs1:~$ rg "^2024-01-.*Bad packet from" /var/log/bird/rs1-ipv*.1 | awk '{print $8}' | sort | uniq -c
     9 2001:504:27::3823:0:2
     2 2001:504:27::8252:0:1
1183836 2001:504:27::b7f8:0:1
     4 2001:504:27::d15d:0:1
1183834 206.108.255.101
  7498 206.108.255.119
   380 206.108.255.121
1463099 206.108.255.137
     3 206.108.255.176
     3 206.108.255.185

root@rs2:~# rg "^2024-01-.*Bad packet from" /var/log/bird/rs2-ipv*.1 | awk '{print $8}' | sort | uniq -c
    12 2001:504:27::1e49:0:1
     1 2001:504:27::3823:0:2
     1 2001:504:27::39:0:1
1457433 2001:504:27::5adc:0:1
     3 2001:504:27::6478:0:1
1457369 2001:504:27::8e16:0:1
     1 2001:504:27::9dbe:0:1
     5 2001:504:27::9dbe:0:2
1179733 2001:504:27::b7f8:0:1
1176975 2001:504:27::d15d:0:1
     4 2001:504:27::e4f:0:1
     1 2001:504:27::f756:0:1
1331747 2001:504:27::f7a2:0:1
1179735 206.108.255.101
  7494 206.108.255.119
  1954 206.108.255.120
     3 206.108.255.137
     3 206.108.255.161
1331745 206.108.255.168
1457437 206.108.255.17
     2 206.108.255.176
     8 206.108.255.185
    11 206.108.255.3
     6 206.108.255.46
1457345 206.108.255.53
     4 206.108.255.92

--
Richard