Re: Can route-views be trusted?

>
> I actually don't know what the "OBSERVED PATHS" is showing here, 35280
> doesn't appear in any of them, so are they the paths "up to" 35280 ?


Presumably  'observed paths from inside 35280', but also think it's a
misleading/confusing tool.

From what I can see for that prefix ( 2a0d:3dc1:6789::/48 ) , origin is
4601 , paths is to 1299. ( 1299 25091 8298 4601 )

1299 doesn't seem to have it anywhere in their LGs, but 174 sure does in
Singapore and Washington, DC.

Tue Mar  3 18:39:11.114 UTC
BGP routing table entry for 2a0d:3dc1:6789::/48
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker         2021417067  2021417067
Last Modified: Feb 25 08:49:15.258 for 6d09h
Paths: (1 available, best #1)
  Path #1: Received by speaker 0
  1299 25091 8298 4601
    2001:550:0:1000::261c:1d4 (metric 118081) from
2001:550:0:1000::9a36:42af (38.28.1.212)
      Origin IGP, metric 4294967294, localpref 100, valid, internal, best,
group-best
      Received Path ID 0, Local Path ID 1, version 2021417067
      Community: 174:10001 174:11700 174:20666 174:21100 174:22020
      Originator: 38.28.1.212, Cluster list: 154.54.66.175, 154.54.136.66,
66.28.1.3, 38.28.1.123

RIPEStat has the withdrawl at  2026-03-02 15:20:08.

So it seems like Cogent is where it's stuck. AS35280 presumably only has
this route because AS174 is still advertising it.

This ThousandEyes tool then saying 'This ASN is potentially retaining stuck
routes' is kinda crap, since Cogent appears to be the actual place it's
stuck. You see the same error message for any ASN that has a path from 174.





On Tue, Mar 3, 2026 at 5:00 AM James Bensley via NANOG <
[email protected]> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
>
> Hi Hank,
>
> It is possible for routes to get stuck in the global routing table,
> although it is pretty rare.
>
> The is a project called the BGP Clock, they announce prefixes, then
> withdraw them, and then check if they are still visible anywhere, to see if
> the prefixes are "stuck". It's called the BGP Clock because they encode the
> time in the IPv6 prefix, so each prefix is unique and you can see when it
> was announced (and thus how long it's been lingering in the DFZ).
>
> F5s ASN in one that shows as potentially having this problem according to
> this tool:
> https://www.thousandeyes.com/bgp-stuck-route-observatory/?asn=35280
>
> Note that this can't be taken as any sort of guarantee and this is just a
> "hint" because there are many variables at play.
>
> I actually don't know what the "OBSERVED PATHS" is showing here, 35280
> doesn't appear in any of them, so are they the paths "up to" 35280 ?
>
>
> With kind regards,
> James.
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