Apr 12 17:57:42 r0.iad rpd[1752]: Prefix Send failed ! 103.148.41.0/24 bgp_rt_trace_too_big_message:1209 path attribute too big. Cannot build update. so some idiot is barfing out a ridiculous as_path. dear lazynet, is there an easy way to get attribution for this stupidity? i.e. the as_path. e.g. a nice query to ris or rv given the prefix, 103.148.41.0/24, and the uct time, Apr 12 17:57:42. randy
I’m using CAIDA’s bgpreader and this one looks like it might be an example of what you want. R|R|1586714402.000000|routeviews|route-views.eqix|||2914|206.126.236.12|103.148.41.0/24|206.126.236.12|2914 58717 134371 134371 134371 134371 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076 140076|140076|2914:410 2914:1405 2914:2406 2914:3400|| —Sandy
aut-num: AS140076 as-name: MIS-AS-AP descr: Mir Internet Service country: BD org: ORG-MIS3-AP admin-c: MISA2-AP tech-c: MISA2-AP mnt-by: APNIC-HM mnt-irt: IRT-MIS-BD mnt-routes: MAINT-MIS-BD mnt-lower: MAINT-MIS-BD last-modified: 2020-01-31T06:35:38Z source: APNIC actually, an example of what none of us wants :) it seems a lot of folk think prepending acrually works. thanks
On 13/Apr/20 23:04, Bryan Holloway wrote:
Oh, it works ... just not for anything pragmatically useful.
In 2020, no less. Can't recall the last time I used this feature, even if it's one we offer for BGP communities we accept from customers. Admittedly, I don't think of any of them use it. Mark.
Well, according to your router's error message, it *did* work...it ensured you couldn't propagate that route update, thereby ensuring no traffic from your neighbors would traverse the prepended path. Of course, it's a bit of a degenerate case of "working"--but it *did* serve to shift traffic away. ^_^;; Matt On Mon, Apr 13, 2020, 13:33 Randy Bush <randy@psg.com> wrote:
On Mon, Apr 13, 2020 at 7:38 PM Brandon Martin <lists.nanog@monmotha.net> wrote:
for ~4 yrs or so there's been possible problems with as-paths longer than ~50 (I think, i can't recall the exact vendor bug) so, folk should have already been denying announcements with longer than ~soemthing-like-45 asn in the path.. right? :) (yes, any prepend past ~10 is arguably not worth the time)
On the point of as-path length limit, Yes I know of at least one tier-1 that does it and since I left some 8 years back I do it everywhere I go. In addition to the above (best common practice, id' say) -on junos you can do community length limiting -and on cisco you can do attribute filtering -hence my question to this forum some time back about whether folks do filter all the "experiments" for the sake of running a successful business (paraphrasing...) adam
participants (8)
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adamv0025@netconsultings.com
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Brandon Martin
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Bryan Holloway
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Christopher Morrow
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Mark Tinka
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Matthew Petach
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Randy Bush
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Sandra Murphy