On 5/11/2008, at 9:13 AM, Holmes,David A wrote:

The Metro Ethernet Forum (MEF) MEF10-1 ELAN multipoint-to-multipoint specification says that multicast packets must be replicated out all ports in the ELAN, except the ingress port. Some carriers have taken this literally and built a virtual ELAN service emulating a 1990's style hub in which all multicast packets are replicated out all ports regardless of the L3 multicast routing protocol in use. In the case of PIM sparse mode real physical Ethernet switches use IGMP snooping to construct a directed path through the switch fabric, so that a given established multicast stream is forwarded just like a directed unicast connection with mac/port table entries establishing a single path through the L2 fabric, and no flooding is done. Some carriers flood directed multicast traffic out all ELAN ports even though a single path should be taken. In networks with a large number of directed multicast streams, flooding out all ports uses unnecessary bandwidth, sometimes rendering a 10 Mb port useless due to oversubscription caused by this unnecessary flooding.

Can anyone suggest a carrier MEF ELAN multipoint-to-multipoint service that does not flood established directed PIM sparse mode streams?

Are you looking for a vendor product, or a service? I'm not aware of any vendor products or services that do what you describe. However, I'd recommend perhaps a L3 VPN service with multicast support and pushing your mcast traffic down it, perhaps talk to your L2 service provider and see if they can provide you with this in parallel to your L2 service. -- Nathan Ward