Long BGP AS paths

Sun Oct 1 04:32:21 UTC 2017

Hi Bill,

Could you list which prefix(es) you saw were being announced with these
long AS paths?

Mark

On Sat, Sep 30, 2017 at 6:29 PM, William Herrin <bill at herrin.us> wrote:

> To the chucklehead who started announcing a 2200+ byte AS path yesterday
> around 18:27 EDT, I beg of you: STOP. You've triggered a bug in Quagga
> that's present in all versions released in the last decade. Your
> announcement causes routers based on Quagga to send a malformed update to
> their neighbors, collapsing the entire BGP session. Every 30 seconds or so.
>
> For everyone else: please consider filtering BGP announcements with
> stupidly long AS paths. There's no need nor excuse for them to be present
> in the DFZ and you could have saved me a painful Saturday.
>
> Cisco:
>
> router bgp XXX
>  bgp maxas-limit 50
>
>
> Juniper:
> https://kb.juniper.net/InfoCenter/index?page=content&id=KB29321
>
>
> Quagga:
>
> ip as-path access-list maxas-limit50 deny ^([{},0-9]+ ){50}
> ip as-path access-list maxas-limit50 permit .*
>
>
> Regards,
> Bill Herrin
>
>
> --
> William Herrin ................ herrin at dirtside.com  bill at herrin.us
> Dirtside Systems ......... Web: <http://www.dirtside.com/>
>