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February 2026

18 participants
22 discussions

Re: bird 3.2.0 - Malformed AS_PATH attribute - AS_SET segment (1) at 26
by Benjamin LaHaise 04 Feb '26

04 Feb '26

Hello Maria, On Wed, Feb 04, 2026 at 10:23:39PM +0100, Maria Matejka wrote: ... > This is a known feature, mandated by RFC 9774, Section 3: ... > It is still possible to `allow as sets` explicitly, if you really need > to keep them. Ah, so this is a case of the RFCs being ahead of what's actually deployed on the Internet. Sadly, I must accept them as otherwise there are holes in the routing table across a number of providers. If it was just 1 provider then new behaviour could be acceptable. Will have to revisit this in 2 or 3 years to see if ISPs have caught up with RFC 9774. Thank you for the quick response -- it is much appreciated. Cheers, -ben -- "Thought is the essence of where you are now."

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bird 3.2.0 - Malformed AS_PATH attribute - AS_SET segment (1) at 26
by Benjamin LaHaise 04 Feb '26

04 Feb '26

Hello all, With Fedora 43's bird 3.2.0-1 rpm installed on an x86_64 system, I'm seeing that several routes are being dropped from a full feed with the log messages below. Using Fedora's bird 3.1.4-1 does not seem to have any issues with the same BGP config and peer. Is this a known bug? What additional information can I provide to aid in the debugging? This is a backup transit connection that is not yet in full production use (but will be soon), so I can help with debugging and testing for now. Cheers, -ben Feb 4 14:42:49 router bird[24317]: upstream: Malformed AS_PATH attribute - AS_SET segment (1) at 14 Feb 4 14:42:49 router bird[24317]: upstream: Invalid route 76.165.0.0/16 withdrawn Feb 4 14:42:49 router bird[24317]: upstream: Malformed AS_PATH attribute - AS_SET segment (1) at 18 Feb 4 14:42:49 router bird[24317]: upstream: Invalid route 204.10.20.0/22 withdrawn Feb 4 14:42:49 router bird[24317]: upstream: Malformed AS_PATH attribute - AS_SET segment (1) at 14 Feb 4 14:42:49 router bird[24317]: upstream: Invalid route 213.186.96.0/19 withdrawn Feb 4 14:42:49 router bird[24317]: upstream: Invalid route 94.178.0.0/15 withdrawn Feb 4 14:42:49 router bird[24317]: upstream: Invalid route 37.52.0.0/14 withdrawn Feb 4 14:42:50 router bird[24317]: upstream: Malformed AS_PATH attribute - AS_SET segment (1) at 26 Feb 4 14:42:50 router bird[24317]: upstream: Invalid route 208.68.112.0/21 withdrawn Feb 4 14:42:50 router bird[24317]: upstream: Malformed AS_PATH attribute - AS_SET segment (1) at 18 Feb 4 14:42:50 router bird[24317]: upstream: Invalid route 147.92.87.0/24 withdrawn Feb 4 14:42:50 router bird[24317]: upstream: Invalid route 52.129.48.0/24 withdrawn Feb 4 14:42:50 router bird[24317]: upstream: Malformed AS_PATH attribute - AS_SET segment (1) at 18 Feb 4 14:42:50 router bird[24317]: upstream: Invalid route 15.20.64.0/18 withdrawn -- "Thought is the essence of where you are now."

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