[c-nsp] CEF and multicast on a 3750

[John Neiberger]

On Tue, Jun 26, 2012 at 9:59 AM, John Gill <johgill at cisco.com> wrote:
> Luckily, buffering issues are easy to check.  Look for output drops in "show
> interface" as well as "sh plat port-asic stats drop gi x/y/z"
>
> Don't forget, as some others have touched on, state changes.  If TCNs occur,
> we fast-age mac addresses - including IGMP-learned.
>
> Who is the mrouter/querier?  Does this device always have igmp/mrouter
> state?  IGMP join/leave activity should be investigated.
>
> It's an important distinction to see if you are missing traffic on all
> receivers, or a subset.

We just solved the problem. It turns out we had mls qos enabled, but
99.999% of the traffic on this box is video, so qos was hurting us. We
were using an older code originally that apparently has a bug that was
hiding the drops from us. The output drop counters were not
incrementing. We upgraded the code and suddenly started seeing the
drops. We then disabled mls qos and now it's running perfectly clean.

Thanks for everyone's help!
John