[c-nsp] CEF and multicast on a 3750

[John Neiberger]

I'm trying to help troubleshoot a really odd multicast issue on a 3750
that involves intermittent dropped packets. The problem seems to be
related to the overall traffic level on the multicast content vlan,
but we can find no explanation for it. There are multicast sources and
receivers in the same vlan. There is a layer three Vlan interface
configured, but it is not being used for routing. It is just a host on
the Vlan. Another router upstream on a trunk is doing the routing and
acting as IGMP snooping querier. However, on the Vlan interface
configured on the switch, I noticed that CEF had been disabled. I have
no idea why, and I thought nothing of it at first, but now I'm
questioning my assumptions. If the layer three interface isn't being
used for routing, would disabling CEF on it have any effect on traffic
within the Vlan?