BGP Notification sent, invalid or corrupt AS path - Page 2

Josiah Inubio · ‎08-25-2015

Hi Everyone,

I've been trying to have an bgp peering on our counterpart but this error keeps on showing. Everytime it's established, it dropped also. Please see logs below. I've already bounced my session, create / re-create my bgp config, but still no avail. Can anyone advise me on this?

RP/0/RP0/CPU0:Aug 25 09:20:31.043 : bgp[1045]:
%ROUTING-BGP-5-ADJCHANGE_DETAIL : neighbor 206.41.72.1 Down - BGP
Notification sent, invalid or corrupt AS path (VRF: default; AFI/SAFI: 1/1)

Connections established 145; dropped 145
Local host: 206.41.72.39, Local port: 11458
Foreign host: 206.41.72.1, Foreign port: 179
Last reset 00:00:14, due to Peer closing down the session
Peer reset reason: Remote closed the session (Connection timed out)
Time since last notification sent to neighbor: 00:01:30
Error Code: invalid or corrupt AS path
Notification data sent:
40020A02 02000051 CC000040 F1

Total malformed UPDATE 145
Last malformed UPDATE 00:01:30
Error subcode 11, attribute code 0, action reset session
Malformed UPDATE: 133 bytes
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF
00850200 00002E40 01010040 020A0202
000051CC 000040F1 400304CE 294822C0
07080000 51CC172D 4359C008 0851CC01
9B51CC03 781317DD 6016B855 E41648F6
A01648F6 CC1748F7 EA14B855 4014173E
40141706 B014173E 501748F6 501417DE
A016173E 3817173E 361417CD C017B81C
2014173B 10

Josiah Inubio · ‎09-02-2015

Hi Peter,

Please see attached.

#show bgp neighbor 206.41.73.1
Wed Sep 2 11:21:05.005 UTC

BGP neighbor is 206.41.73.1
Remote AS, local AS, external link
Description: ::PEERING
Remote router ID 206.41.73.1
BGP state = Established, up for 1w1d
Last read 00:00:30, Last read before reset 00:00:00
Hold time is 180, keepalive interval is 60 seconds
Configured hold time: 180, keepalive: 60, min acceptable hold time: 3
Last write 00:00:00, attempted 19, written 19
Second last write 00:01:00, attempted 19, written 19
Last write before reset 00:00:00, attempted 0, written 0
Second last write before reset 00:00:00, attempted 0, written 0
Last write pulse rcvd Sep 2 11:21:04.835 last full not set pulse count 26456
Last write pulse rcvd before reset 00:00:00
Socket not armed for io, armed for read, armed for write
Last write thread event before reset 00:00:00, second last 00:00:00
Last KA expiry before reset 00:00:00, second last 00:00:00
Last KA error before reset 00:00:00, KA not sent 00:00:00
Last KA start before reset 00:00:00, second last 00:00:00
Precedence: internet
Enforcing first AS is enabled
Neighbor capabilities:
Route refresh: advertised and received
4-byte AS: advertised and received
Address family IPv4 Unicast: advertised and received
Received 14057 messages, 0 notifications, 0 in queue
Sent 12480 messages, 0 notifications, 0 in queue
Minimum time between advertisement runs is 30 secs

For Address Family: IPv4 Unicast
BGP neighbor version 328579802
Update group: 0.36 Filter-group: 0.13 No Refresh request being processed
Inbound soft reconfiguration allowed (override route-refresh)
Private AS number removed from updates to this neighbor
Route refresh request: received 0, sent 0
Policy for incoming advertisements is PEERING-IN
Policy for outgoing advertisements is ALL-OUT
0 accepted prefixes, 0 are bestpaths
Cumulative no. of prefixes denied: 0.
Prefix advertised 669, suppressed 36, withdrawn 22
Maximum prefixes allowed 1048576
Threshold for warning message 75%, restart interval 0 min
An EoR was not received during read-only mode
Last ack version 328579802, Last synced ack version 0
Outstanding version objects: current 0, max 3
Additional-paths operation: None

Connections established 1; dropped 0
Local host: 206.41.73.39, Local port: 179
Foreign host: 206.41.73.1, Foreign port: 39574
Last reset 00:00:00

Josiah Inubio · ‎09-02-2015

Hi Peter,

We've just put this "enforce-first-as disable" on our config and our bgp peering established.

rdeguzman75 · ‎09-01-2023

i've had this happen when the as path prepend being sent was different than what the actual as of the bgp router is. from the messages you get, this is likely your neighbor sending the wrong as value in their as prepend statement.

Peter Paluch · ‎09-01-2015

Josiah,

In addition, can you please post the output from show bgp neighbor 206.41.73.1 ?

Thanks!

Best regards,
Peter

p-smallwood · ‎04-28-2018

I have seen the message %BGP-3-NOTIFICATION: sent to neighbor (invalid or corrupt AS path) when an eBGP neighbor is configured to AS-Prepend using an AS number that is different from it's own.