<div dir="ltr"><div>Hi, </div><div class="gmail_quote gmail_quote_container"><div dir="ltr"><div><br></div><div>Strange problem here. We have just turned up a new CDN at our IXP - EdgeNext. Our Route Server is refusing to peer with them, citing the error "Malformed AS_PATH". Tcpdump shows them having a "my AS" of 123456 - which it seems Bird is misunderstanding.</div><div><br></div><div>Any idea how we can fix this? Is there a skin/neighbor profile that we can configure for them?</div><div><br></div><div>Here is output from birdc show protocol:</div><div><br></div><div>root@rs1:/home/devops# /usr/sbin/birdc -s /var/run/bird/bird-rs1-lan1-ipv4.ctl<br>BIRD 2.19.1 ready.<br>bird> show protocols all pb_0025_as139057<br>Name Proto Table State Since Info<br>pb_0025_as139057 BGP --- start 2026-07-22 14:45:32 Idle Received: Malformed AS_PATH<br> Description: AS139057 - CDN EdgeNext<br> BGP state: Idle<br> Neighbor address: 196.x.y.z<br> Neighbor AS: 139057<br> Local AS: 37800<br> Error wait: 35.054/60<br> Last error: Received: Malformed AS_PATH<br> Channel ipv4<br> State: DOWN<br> Table: t_0025_as139057<br> Preference: 100<br> Input filter: f_import_as139057<br> Output filter: f_export_as139057<br> Import limit: 1000<br> Action: restart</div><div><br></div><div>And here is output from tcpdump packet capture:</div><div>11:38:15.176666 ens18 In IP (tos 0xc0, ttl 1, id 36934, offset 0, flags [none], proto TCP (6), length 123)<br> 196.60.122.44.49581 > rs1-lan1-ipv4.bgp: Flags [P.], cksum 0x56b2 (correct), seq 1:72, ack 1, win 5840, options [nop,nop,TS val 41713288 ecr 3839994927], length 71: BGP<br> Open Message (1), length: 71<br> Version 4, my AS 23456, Holdtime 180s, ID 172.16.0.1<br> Optional parameters, length: 42<br> Option Capabilities Advertisement (2), length: 6<br> Multiprotocol Extensions (1), length: 4<br> AFI IPv4 (1), SAFI Unicast (1)<br> 0x0000: 0001 0001<br> Option Capabilities Advertisement (2), length: 2<br> Route Refresh (Cisco) (128), length: 0<br> Option Capabilities Advertisement (2), length: 2<br> Route Refresh (2), length: 0<br> Option Capabilities Advertisement (2), length: 16<br> Graceful Restart (64), length: 14<br> Restart Flags: [none], Restart Time 120s<br> AFI IPv4 (1), SAFI Unicast (1), Forwarding state preserved: yes<br> AFI IPv6 (2), SAFI Unicast (1), Forwarding state preserved: yes<br> AFI VPLS (25), SAFI EVPN (70), Forwarding state preserved: yes<br> 0x0000: 0078 0001 0180 0002 0180 0019 4680<br> Option Capabilities Advertisement (2), length: 6<br> 32-Bit AS Number (65), length: 4<br> 4 Byte AS 139057<br> 0x0000: 0002 1f31<br> 0x0000: 45c0 007b 9046 0000 0106 abce c43c 7a2c E..{.F.......<z,<br> 0x0010: c43c 7a03 c1ad 00b3 da49 51e5 b19f 25d5 .<z......IQ...%.<br> 0x0020: 8018 16d0 56b2 0000 0101 080a 027c 7e88 ....V........|~.<br> 0x0030: e4e1 ac2f ffff ffff ffff ffff ffff ffff .../............<br> 0x0040: ffff ffff 0047 0104 5ba0 00b4 ac10 0001 .....G..[.......<br> 0x0050: 2a02 0601 0400 0100 0102 0280 0002 0202 *...............<br> 0x0060: 0002 1040 0e00 7800 0101 8000 0201 8000 ...@..x.........<br> 0x0070: 1946 8002 0641 0400 021f 31 .F...A....1<br>11:38:15.176686 ens18 Out IP (tos 0xc0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40)<br> rs1-lan1-ipv4.bgp > 196.60.122.44.49581: Flags [R], cksum 0x9962 (correct), seq 2979997141, win 0, length 0<br> 0x0000: 45c0 0028 0000 4000 4006 bd67 c43c 7a03 E..(..@.@..g.<z.<br> 0x0010: c43c 7a2c 00b3 c1ad b19f 25d5 0000 0000 .<z,......%.....<br> 0x0020: 5004 0000 9962 0000 P....b..<br>11:38:26.177549 ens18 In IP (tos 0xc0, ttl 1, id 37226, offset 0, flags [none], proto TCP (6), length 60)<br> 196.60.122.44.43812 > rs1-lan1-ipv4.bgp: Flags [S], cksum 0x6704 (correct), seq 2085855246, win 5840, options [mss 1460,sackOK,TS val 41714388 ecr 0,nop,wscale 0], length 0<br> 0x0000: 45c0 003c 916a 0000 0106 aae9 c43c 7a2c E..<.j.......<z,<br> 0x0010: c43c 7a03 ab24 00b3 7c53 a00e 0000 0000 .<z..$..|S......<br> 0x0020: a002 16d0 6704 0000 0204 05b4 0402 080a ....g...........<br> 0x0030: 027c 82d4 0000 0000 0103 0300 .|..........<br>11:38:26.177593 ens18 Out IP (tos 0xc0, ttl 255, id 0, offset 0, flags [DF], proto TCP (6), length 60)<br> rs1-lan1-ipv4.bgp > 196.60.122.44.43812: Flags [S.], cksum 0x7cd7 (incorrect -> 0x8971), seq 316352219, ack 2085855247, win 65160, options [mss 1460,sackOK,TS val 3840005929 ecr 41714388,nop,wscale 7], length 0<br> 0x0000: 45c0 003c 0000 4000 ff06 fe52 c43c 7a03 E..<..@....R.<z.<br> 0x0010: c43c 7a2c 00b3 ab24 12db 26db 7c53 a00f .<z,...$..&.|S..<br> 0x0020: a012 fe88 7cd7 0000 0204 05b4 0402 080a ....|...........<br> 0x0030: e4e1 d729 027c 82d4 0103 0307 ...).|......<br>11:38:26.179093 ens18 In IP (tos 0xc0, ttl 1, id 37227, offset 0, flags [none], proto TCP (6), length 52)<br> 196.60.122.44.43812 > rs1-lan1-ipv4.bgp: Flags [.], cksum 0x9ff6 (correct), seq 1, ack 1, win 5840, options [nop,nop,TS val 41714388 ecr 3840005929], length 0<br> 0x0000: 45c0 0034 916b 0000 0106 aaf0 c43c 7a2c E..4.k.......<z,<br> 0x0010: c43c 7a03 ab24 00b3 7c53 a00f 12db 26dc .<z..$..|S....&.<br> 0x0020: 8010 16d0 9ff6 0000 0101 080a 027c 82d4 .............|..<br> 0x0030: e4e1 d729 ...)<br>11:38:26.179093 ens18 In IP (tos 0xc0, ttl 1, id 37228, offset 0, flags [none], proto TCP (6), length 52)<br> 196.60.122.44.43812 > rs1-lan1-ipv4.bgp: Flags [.], cksum 0x9ff6 (correct), seq 1, ack 1, win 5840, options [nop,nop,TS val 41714388 ecr 3840005929], length 0<br> 0x0000: 45c0 0034 916c 0000 0106 aaef c43c 7a2c E..4.l.......<z,<br> 0x0010: c43c 7a03 ab24 00b3 7c53 a00f 12db 26dc .<z..$..|S....&.<br> 0x0020: 8010 16d0 9ff6 0000 0101 080a 027c 82d4 .............|..<br> 0x0030: e4e1 d729 ...)<br>11:38:26.179093 ens18 In IP (tos 0xc0, ttl 1, id 37229, offset 0, flags [none], proto TCP (6), length 123)<br> 196.60.122.44.43812 > rs1-lan1-ipv4.bgp: Flags [P.], cksum 0xeb7e (correct), seq 1:72, ack 1, win 5840, options [nop,nop,TS val 41714388 ecr 3840005929], length 71: BGP<br> Open Message (1), length: 71<br> Version 4, my AS 23456, Holdtime 180s, ID 172.16.0.1<br> Optional parameters, length: 42<br> Option Capabilities Advertisement (2), length: 6<br> Multiprotocol Extensions (1), length: 4<br> AFI IPv4 (1), SAFI Unicast (1)<br> 0x0000: 0001 0001<br> Option Capabilities Advertisement (2), length: 2<br> Route Refresh (Cisco) (128), length: 0<br> Option Capabilities Advertisement (2), length: 2<br> Route Refresh (2), length: 0<br> Option Capabilities Advertisement (2), length: 16<br> Graceful Restart (64), length: 14<br> Restart Flags: [none], Restart Time 120s<br> AFI IPv4 (1), SAFI Unicast (1), Forwarding state preserved: yes<br> AFI IPv6 (2), SAFI Unicast (1), Forwarding state preserved: yes<br> AFI VPLS (25), SAFI EVPN (70), Forwarding state preserved: yes<br> 0x0000: 0078 0001 0180 0002 0180 0019 4680<br> Option Capabilities Advertisement (2), length: 6<br> 32-Bit AS Number (65), length: 4<br> 4 Byte AS 139057<br> 0x0000: 0002 1f31<br> 0x0000: 45c0 007b 916d 0000 0106 aaa7 c43c 7a2c E..{.m.......<z,<br> 0x0010: c43c 7a03 ab24 00b3 7c53 a00f 12db 26dc .<z..$..|S....&.<br> 0x0020: 8018 16d0 eb7e 0000 0101 080a 027c 82d4 .....~.......|..<br> 0x0030: e4e1 d729 ffff ffff ffff ffff ffff ffff ...)............<br> 0x0040: ffff ffff 0047 0104 5ba0 00b4 ac10 0001 .....G..[.......<br> 0x0050: 2a02 0601 0400 0100 0102 0280 0002 0202 *...............<br> 0x0060: 0002 1040 0e00 7800 0101 8000 0201 8000 ...@..x.........<br> 0x0070: 1946 8002 0641 0400 021f 31 .F...A....1<br><br><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>--</div><div>Brian Munyao Longwe</div><div>IXP Coordinator | Cell: +265999708883</div><div><a href="https://lionex.org" target="_blank"><img alt="https://lionex.org" src="https://ci3.googleusercontent.com/mail-sig/AIorK4xJpwdHsBCQuenqp2oA-Ybvd4brYWH0KCcnblD5Wk1Jiedkvmlbd9hujA3vKzAcGpVQY8Uz2rEo1J7T"></a></div></div></div></div></div>
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