At Layer2, the difference is subtle. At Layer3, it's different! As
others pointed out, 01:00:5E will lead every IP multicast packet at
Layer2 (it's all about the handoff to higher functions in the switch).
Any other Layer2 "group" address which does not have specific code
attached to it will be replicated to all devices in that broadcast domain.
There are many group addresses though, that DO have other code to
intercept... Spanning Tree is an L2 multicast address.... CDP is...
Just to name a couple!
It's all about awareness though. if the switch isn't aware, it will
flood the frame. The PC then is presumed to be aware of whether it's
part of that group or not.
HTH,
Scott
*Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,
CCDE #2009::D, CCNP-Voice, JNCIE-SP #153, JNCIE-ER #102, CISSP, et al.
CCSI #21903, JNCI-SP, JNCI-ER
swm_at_emanon.com
Knowledge is power.
Power corrupts.
Study hard and be Eeeeviiiil......
On 9/28/11 11:10 AM, CCIE KID wrote:
> Hi fellas,
>
> I have a million dollar doubt. Whether switches understand multicast or not.
> Its all about the so called I/G bit setting in the MAC frame. If the I bit
> is set to 1 then its a multicast address . But unfortunately the broadcast
> address also has the I bit set to 1 . So how does a switch differentiate
> multicast and broadcast. Is there any method used in cisco switches to
> differentiate. Can anyone help me out?
Blogs and organic groups at http://www.ccie.net
Received on Wed Sep 28 2011 - 12:43:34 ART
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