I do a show mac in a new Sup2 CatOS 7.6(1) on a 4506 I see some many
ports with Xmit-Multicast equaling about 50% of the traffice. How can I
track down the source. This is only a Layer 2 network, no routers. I am
getting some complaints about Mitel IP Phones cutting in/out that sounds
like lost packets (could be Mitel phone/dsp firmware, but I want my show
mac to be clean before I point to Mitel... Seperately I see show in-lost
and out-lost on almost all the ports, about 5% of traffic.
I plugged into a port and did a sniffer trace. I see multicast traffic with a source of Symbol (we use their wireless phones with Mitel) destination is 01-a0-f8-f0-f0-04. How can I filter multicast from a layer 2 perspective with 4500/6500 switches? There are no routers.
Filtering multicasts is something that you do not want to do. In general, they represent a very low volume of the total bandwidth that is available.
One may get a wrong impression about this when a sniffer is attached to a network port where no other host is active. In that case, you only observe bcast, multicast and unknown destination mac adresses. This may seem a large amount of traffic but it is in fact a very little one.
In general I agree, but in this case the multicast traffic across all ports equals about 50% of the unicast traffic, and can't be explained. 50% seems unusual. Why send a broadcast across trunks to hosts that don't need the traffic? Multicast makes switching useless in a layer2 environment. We are back at hubs and bridges..when your hosts are across L3 links multicast is great..
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...