[FROG] Tunnel Encap attribute sub-tlv length 48582, exceeds remaining length 28

[Donald Sharp]

Mike -

Yes, we have had people asking about this in slack too.  We have
investigated and found a root cause and are putting patches together
now.  Effectively if you build FRR w/ vnc enabled
(--enable-bgp-vnc=yes) you will be seeing this problem as that VNC
also was using attribute type 255 and reading the length as `wrong`
and resetting the connection.

To solve this for yourself right now:

Rebuild FRR w/ `--disable-bgp-vnc` and reinstall.  If you are using
our build artifacts we are working on new ones now.

donald

On Mon, Jan 7, 2019 at 10:41 AM Mike Tancsa <mike at sentex.net> wrote:
>
> A couple  of my peers started flapping for some reason this morning with
> the error messages
>
>
> Jan  7 09:48:39 bgpd[19828]: Tunnel Encap attribute sub-tlv length 48582
> exceeds remaining length 28
> Jan  7 09:48:39 bgpd[19828]: %NOTIFICATION: sent to neighbor
> xx.yy.zz.205 3/9 (UPDATE Message Error/Optional Attribute Error) 35
> bytes e0 ff 20 ac d9 bd c6 ec 73 13 8f f0 6d ed c7 52 11 5a 91 3c 0e 8b
> 8c 1e be aa f2 72 d5 83 92 83 5e 5b 57
> Jan  7 09:48:39 bgpd[19828]: xx.yy.zz.205: Attribute VNC, parse error
> Jan  7 09:48:39 bgpd[19828]: %ADJCHANGE: neighbor xx.yy.zz.205(Unknown)
> in vrf Default Down BGP Notification send
>
> I was running frr 3.0.3 on FreeBSD RELENG11. Any idea what this bug is
> or problematic advertisement ? I started a pcap of the bgp sessions, but
> havent found anything obvious yet
>
> --
> -------------------
> Mike Tancsa, tel +1 519 651 3400 x203
> Sentex Communications, mike at sentex.net
> Providing Internet services since 1994 www.sentex.net
> Cambridge, Ontario Canada
>
>
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