Basic Multicast Question - Catalyst 3560 and 3750

innesimiller · ‎09-04-2012

I am currently designing a network which requires Multicasting, for UDP video traffic from multiple IP security cameras. This is the first time that I have had to use Multicasting, having relied so far on multiple unicast streams from the devices, I would be very grateful if anyone could comment on my understanding of the set-up of the system as I will outline below, the infrastructure and topology is exactly the same as I have deployed previously, it is just the multicast element that is new:

The network consists of 5 x 3560 switches, with a backbone 3750 connecting via fibre to each of the 3560s. The devices (cameras) are connected to the 3560s (there are around 50), which emit multicast UDP video traffic. The traffic is received by workstations connected to the 3560s (either 1,2 or 3 per switch). There are no routers connected as the network is closed and self-contained (it is a security network)

My understanding is that the following needs to take place:

1) IGMP snooping needs to be enabled on the 3560s

2) IGMP querying needs to be enabled on one of the switches, as it is a Layer 2 network only, so I do not need a router to handle the IGMP requests, my preference would be to enable it on the backbone 3750.

The network should now handle the multicast traffic and prevent flooding using the IGMP snooping feature.

My questions would be:

1) Are the above assumptions correct?

2) Which IOS image should I use, Base IP etc?

3) According to the research I have completed, the 3560s and 3750s support both the IGMP snooping and querying functions, am I wrong?

4) Is there anything that I have missed, or need to consider in addition to the above?

If you are able to comment I would be very grateful, as it is the first time that I have used this forum please excuse any first-time errors!

Thank you for your help,

Joseph W. Doherty · ‎09-05-2012

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Posting

Hmm, looks like you got it all right.

Base IP image should, I believe, suffice too.

One thing you might want to be aware of, if not already, multiple IP multicast addresses map to the same Ethernet multicast address, so if you want to insure you obtain the full benefit of limiting multicast flooding at L2, avoid using the same Ethernet multicast addresses unless the receiving host desires those multicast packets too.