Customer reported 'Malformed Attribute DOMIAN_PATH' log entries on their BGP-speaking router. This article explains possible reason of seeing them. 

The following logs are seeing on BGP-speaking router:

Nov 17 22:32:23 router rpd[16576]: Received malformed update from x.x.x.x (External AS ABC)
Nov 17 22:32:23 router rpd[16576]: Family inet-unicast, prefix a.a.a.a/b
Nov 17 22:32:23 router rpd[16576]: Malformed Attribute DOMIAN_PATH(36) flag 0xc0 length 8 error 5 (Attribute length error).
Nov 17 22:37:23 router rpd[16576]: Total incoming malformed attributes from x.x.x.x (External AS ABC) since last logging
Nov 17 22:37:23 router rpd[16576]: Received 1 malformed attribute DOMIAN_PATH(36)

The malformed log is seen because, the knob "domain-path-id receive" is not enabled.

With a fix of PR1763063, the software behavior changed. The "domain-path-id receive" configuration is required to control importing domain path. 

#set protocols bgp group <GROUP> neighbor <PEER-IP> domain-path-id receive

The importing of this attribute is disabled by default. When this knob is not enabled, software treats the domain_path as unrecognized attribute, drop it, and print log message.

"domain-path-id send" knob can also be configured if domain-path-id needs to be sent from one peer to another.

2024-11-25 : Article Created

2025-02-24: Major formatting changes

2026-02-09: Published

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/routing-options-dpath-domain-id.html