Can the Catalyst 3560 be configured to switch off MAC multicast addresses rather than IP multicast addresses?

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Jan 10th, 2010
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Can the Catalist 3560 be configured to switch off MAC multicast addresses rather than IP multicast addresses?

If not, what does it switch off if the multicast data is not IPv4 or IPv6? Or does it forward the data to all ports?

In addtion, if the multicast group is on more than one vlan, how is multicast vlan registration performed if the IGMP snooping and IP switching is not allowed?


Constraints:

I have a network where a sinlge multicast group is a member of multiple VLANs.

IGMP snooping is not allowed.

IP mulitcast address switching is not allowed as the IP data is not visible by the 3560?


Do I have to duplicate the multicast stream for each VLAN or can some other mechanism be used in this scenario?

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Giuseppe Larosa Mon, 01/11/2010 - 02:49
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Hello tempest,


MAC addresses are OSI layer2 concepts so multicast frames even if not carrying IPv4 or IPv6 frames are flooded out all ports in vlan.


To perform multicast routing the device has to be able to understand the upper layer protocols in the multicast frames exactly as it happens for unicast traffic.


When you say :

>> IP mulitcast address switching is not allowed as the IP data is not visible by the 3560?


C3560 supports IPv4 multicast routing or do you mean your traffic is encrypted in a way that the switch cannot understand upper layer protocols in the frame?


see

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_44_se/configuration/guide/swmcast.html


Hope to help

Giuseppe

tempest26 Mon, 01/11/2010 - 20:11
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Grazie Giuseppe,


>>C3560 supports IPv4 multicast routing or do you mean your traffic is encrypted in a way that the switch cannot understand upper layer protocols in the frame?


Correct, this is precisely what I mean.


However, I though that non-IP multicast traffic can be pruned using MAC addresses if CGMP or GMRP is used.  So the alternative solution to IGMP snooping and IP Mulitcast routing is to use CGMP (client) or GMRP. This would pass the IGMP messages using a layer 2 protocol such as GARP.


However, I don't think these protocols are supported on the 3560 as the statement below shows that the 3560 uses IP multicast group based bridging rather than MAC address based bridging.


"The Catalyst 3560 switch supports IP multicast group-based bridging, rather than MAC-addressed based groups."  from Catalyst 3560 Switch
Software Configuration Guide Cisco IOS Release 12.1(19)EA1.


I am a cisco novice though - so hence this post.


Thanks

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