[c-nsp] BFD CPU hog and traceback on me3600 and isis flapping 15.3(3)S1a

[Pete Lumbis]

Just to close the loop on the thread, I spoke to OP off-list and this
matches CSCug77067. When an FRR event (either TE FRR or IP FRR) occurs the
processes prioritization for BFD and the FRR event doesn't do what it's
supposed to and BFD triggers a CPU hog. It's also possible, as Adam saw,
for BFD neighbors to flap. This is fixed in 15.4.1S1 and 15.3.3S2

-Pete


On Tue, Mar 18, 2014 at 8:27 AM, Vitkovský Adam <adam.vitkovsky at swan.sk>wrote:

>  Hello Pete,
>
> I wasn't performing the upgrade and the guy who did is not sure whether it
> was immediate.
>
> Anyways he eventually noticed that within an hour or so.
>
> Right now it is running smoothly for nearly 23 hours.
>
>
>
>
>
> adam
>
>
>
> *From:* Pete Lumbis [mailto:alumbis at gmail.com]
> *Sent:* Tuesday, March 18, 2014 12:41 AM
> *To:* Vitkovský Adam
> *Cc:* cisco-nsp at puck.nether.net
> *Subject:* Re: [c-nsp] BFD CPU hog and traceback on me3600 and isis
> flapping 15.3(3)S1a
>
>
>
> How soon after the upgrade to 15.4.1 did you see the issue again?
>
> What was that time difference compared to when you re-enabled BFD to show
> TAC and now (assuming it's still stable)?
>
>
>
> On Mon, Mar 17, 2014 at 11:36 AM, Vitkovský Adam <adam.vitkovsky at swan.sk>
> wrote:
>
> Hi folks,
>
> Anyone ran into issues with BFD on me3600 running 15.3(3)S1a or 15.4(1)S1
>
> This particular ring is up for about 3 weeks.
> Yesterday on one of the nodes where no customers are connected yet one
> colleague of mine noticed some BFD process CPU hogs and some tracebacks and
> ISIS sessions flapping cause of the BFD flaps.
> Upgrade to 15.4(1)S1 and reload did not help. What helped was to remove
> the "isis bfd" from the interface.
>
> Strange enough when I added the "isis bfd" back today so that I can see
> what's going on and to open up the case with cisco nothing happened.
> So this might be some slow buffer overflow.
>
> Has anyone experienced something like this please?
>
>
> adam
>
>
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