Metro Ethernet Multicast Support

From: Holmes,David A (no email)
Date: Tue Nov 04 2008 - 15:13:35 EST

  • Next message: Charles Wyble: "On the subject of multihoming"

    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?


  • Next message: Charles Wyble: "On the subject of multihoming"





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