Sunday, May 2, 2021

PSA: PAN-OS Drops BGP peers with an invalid NLRI / Always filter inbound prefixes from Avi Vantage

If Avi Vantage IPAM cannot allocate an address for a new vIP, it will advertise an all-zeros host address - 0.0.0.0/32:


This will cause Palo Alto PAN-OS to restart a peer - even if it is not the immediate downstream prefix. Palo Alto uses routed as their dynamic routing engine - so this is probably default behavior inherited from there:

**** EXCEPTION   0x4103 - 57   (0000) **** I:008e7cd1 F:00000004
qbmlpar2.c 1352 :at 20:54:21, 2 May 2021 (1822572648 ms)
UPDATE message contains NLRI of 0.0.0.0.

**** PROBLEM     0x4102 - 46   (0000) **** I:008e7cd1 F:00000004
qbnmmsg.c 1074 :at 20:54:21, 2 May 2021 (1822572648 ms)
NM has received an UPDATE message that failed to parse.
Entity index               = 1
Local address              = 10.6.64.9
Local port                 = 0
Remote address             = 10.6.64.12
Remote port                = 0
Scope ID                   = 0

**** EXCEPTION   0x4102 - 71   (0000) **** I:008e7cd1 F:00000020
qbnmsnd2.c 167 :at 20:54:21, 2 May 2021 (1822572648 ms)
A NOTIFICATION message is being sent to a neighbor due to an unexpected
problem.
NM entity index       = 1
Local address         = 10.6.64.9
Local port            = 0
Remote address        = 10.6.64.12
Remote port           = 0
Scope ID              = 0
Remote AS number      = 64905
Remote BGP ID         = 0X0A06400C
Error code            = UPDATE Message Error (3)
Error subcode         = Invalid Network Field (10)

This could cause a network outage for all subtending networks on this peer. Consider this a friendly reminder to always leverage route filtering between autonomous systems!

Unfortunately, strict import filters on PAN-OS did not resolve this issue.

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