nanog mailing list archives
Re: BGP and The zero window edge
From: Job Snijders via NANOG <nanog () nanog org>
Date: Thu, 22 Apr 2021 01:24:54 +0200
On Wed, Apr 21, 2021 at 09:22:57PM +0000, Jakob Heitz (jheitz) wrote:
I'd like to get some data on what actually happened in the real cases and analyze it. [snip] TCP zero window is possible, but many other things could cause it too.
Indeed. There could be a number of reasons that caused it. Switchings away from TCP win=0 towards "Zombie Routes": *RIGHT NOW* (at the moment of writing), there are a number of zombie route visible in the IPv6 Default-Free Zone: One example is http://lg.ring.nlnog.net/prefix_detail/lg01/ipv6?q=2a0b:6b86:d15::/48 2a0b:6b86:d15::/48 via: BGP.as_path: 204092 57199 35280 6939 42615 42615 212232 BGP.as_path: 208627 207910 57199 35280 6939 42615 42615 212232 BGP.as_path: 208627 207910 57199 35280 6939 42615 42615 212232 (first announced April 15th, last withdrawn April 15th, 2021) Another one is http://lg.ring.nlnog.net/prefix_detail/lg01/ipv6?q=2a0b:6b86:d24::/48 2a0b:6b86:d24::/48 via: BGP.as_path: 201701 9002 6939 42615 212232 BGP.as_path: 34927 9002 6939 42615 212232 BGP.as_path: 207960 34927 9002 6939 42615 212232 BGP.as_path: 44103 50673 9002 6939 42615 212232 BGP.as_path: 208627 207910 34927 9002 6939 42615 212232 BGP.as_path: 3280 34927 9002 6939 42615 212232 BGP.as_path: 206628 34927 9002 6939 42615 212232 BGP.as_path: 208627 207910 34927 9002 6939 42615 212232 (first announced March 24th, last withdrawn March 24th, 2021) Just now, I literally rebooted the BGP speaker behind lg.ring.nlnog.net to make ensure that those routes are not stuck in the BGP looking glass itself. 2a0b:6b86:d24::/48 was first announced on March 24th, 2021, and withdrawn at the end of March 24th, 2021 by the originator, and now almost a month later, this prefix still is visible in the default-free zone despite WITHDRAW messages having been sent and the AS 212232 operator confirming they are not announcing that IP prefix anywhere. I checked the AS 6939 Looking glass, but the d24::/48 route is not visible in the http://lg.he.net/ web interface. This leads me to believe the the route got stuck somewhere along way in either of 201701, 204092, 206628, 207910, 207960, 208627, 3280, 34927, 35280, 44103, 50673, 57199, and/or 9002. This implies indeed might be multiple reasons a BGP route gets stuck ('stuck' as in - a WITHDRAW was not generated, or ignored). Perhaps on any one of these edges there is a very high Out Queue for one reason or another: 34927 9002 206628 34927 44103 50673 207960 34927 3280 34927 9002 6939 201701 9002 208627 207910 I'm not sure all the these sightings of stuck routes can be pinpointed to one specific BGP vendor (or one bug). Kind regards, Job
Current thread:
- BGP and The zero window edge Jean St-Laurent via NANOG (Apr 21)
- <Possible follow-ups>
- RE: BGP and The zero window edge Jakob Heitz (jheitz) via NANOG (Apr 21)
- Re: BGP and The zero window edge Job Snijders via NANOG (Apr 21)
- RE: BGP and The zero window edge Jakob Heitz (jheitz) via NANOG (Apr 21)
- Re: BGP and The zero window edge Job Snijders via NANOG (Apr 21)
- RE: BGP and The zero window edge Philip Loenneker (Apr 21)
- Re: BGP and The zero window edge Hank Nussbacher (Apr 21)
- Re: BGP and The zero window edge Alexandre Snarskii (Apr 22)
- Re: BGP and The zero window edge Job Snijders via NANOG (Apr 22)
- Re: BGP and The zero window edge Simon Leinen (Apr 24)
- Re: BGP and The zero window edge Alarig Le Lay (Apr 25)
- Re: BGP and The zero window edge Job Snijders via NANOG (Apr 21)