[Cialug] Multicast, anyone?

[jeff at ocjtech.us]

On Mon, Oct 25, 2010 at 8:38 AM, Nathan C. Smith <nathan.smith at ipmvs.com> wrote:
> I've messed about with Multicast video on my network.  You can quickly slow everything with the addition of a lot of multicast traffic and some old devices (in our case, printers).  We have some old HP Laserjet 4 printers that were horribly burdened by receiving all the multicast packets (not sure why they were) and printouts would take 5 minutes and longer per page.

Some networking gear is pretty stupid and can't deal with extraneous
traffic in an efficient manner.  The printers probably didn't have a
hardware MAC address filter and had to process every packet in
software, even if the packet wasn't intended for the printer.

> In the end everything seemed to work but it was really scary seeing all the ports lit solid.  Something I thought would not happen once I enabled IGMP snooping.

Different implementations of IGMP snooping work better than others...

> So I guess my guidance is: don't start working with multicast during peak hours on your production network until you have some confidence with how to configure your switches.

Depending on your level of paranoia, you shouldn't make any changes to
a production network without scheduling an outage.

-- 
Jeff Ollie