Unanswered Question
Feb 28th, 2008

Hi all, am i right in saying switches treat multicast the same as broadcasts, are these multicasts limited to each vlan ?

I have this problem too.
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Joseph W. Doherty Thu, 02/28/2008 - 05:34

Unless multicast routing is active, multicast normally stops at L3.

As to switches treating multicast the same as broadcast, those without any multicast snooping do. Those with snooping treat multicast more like unicast, i.e. only forwarded where desired, the switch blocks needless multicast streams.

Most modern Enterprise level switches have the capability to block needless multicast to hosts (e.g. IGMP snooping). Some also support blocking needless multicast to routers (e.g. PIM snooping).


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