SLB, Pix & Multicast

Unanswered Question
Mar 14th, 2007

I've had a good search of the website but don't seem to be able to find out what I need about SLB & multicasting.

What I am trying to do is set up SLB for about 4 firewalls, whilst I know this is possible and have found the documents I need, I can't find out anything about doing SLB across firewalls with multicasting going across.

Is there any documentation on this specific set up or has anyone had experience of doing multicasting across SLB & Pix. Can it be done or are there too many problems with it.

The switches are 6500's and the Pix are 515E with version 7 installed.


I have this problem too.
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bwilmoth Tue, 03/20/2007 - 07:06

Multicast is supported only in bridge mode: multicast can be bridged between 2 VLANs, but NOT processed in any other way, so no NAT and no balancing

Mel Popple Fri, 03/23/2007 - 15:24

Thanks for the reply,

I would agree with bridging but the following is another issue.

1x 6500 outside, 3(or more)x Pix in between and then 2x 6500 in the center, the receiving servers beyond that are on a single subnet.

Many multicast senders from equal cost distance away to any number of recievers on the same network - balanced across all the Pix so not to swamp any of them.

Which has to be scaleable and redundant, of course :o)

I am at a stand still on this one and believe that it isn't possible.......

mikedavi1 Fri, 03/23/2007 - 17:12

Not sure bridging would've bought you much anyway since Spanning Tree would have left you with one PIX to move traffic through.

You may or may not have limitations around existing equipment, but here's a couple of avenues for you to explore:

PIX/ASA PIM-SM & BIDIR configuration example:

Equal Cost Multipath Multicast Load Splitting

You might be able to get creative with these. I'm thinking the receivers 6500s load split their joins across the PIXes, each pix joins the sender-side 6500 DR.

What do you think?

HTH a bit,



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