> Dino, > > At Toronto NV03 session, you suggested that > draft-ghanwani-nvo3-app-mcast-framework can use LISP’s signal free multicast > scheme. > After studying the draft-farinacci-lisp-signal-free-multicast-00, I agree > that the proposed scheme can definitely solve the problem of application > initiated multicast in environment where underlay network don’t support any > IP multicast protocol.
The design allows for either unicast or multicast RLOCs to be registered to the mapping system. So LISP signal-free multicast can be used when the underlay supports multicast. > But there are some issues of using the LISP’s signal free multicast > mechanism in Data Centers when NVEs, especially the server based hypervisor > virtual switches, don’t ( or can’t) support the “General Receiver-site > procedure” documented in the “draft-farinacci-list-signal-free-multicast-00”. > The general Whatever the application is going to use to tell the network what multicast groups are joined can be used as well. > receiver-site procedure requires egress edge (i.e. egress NVE) to terminate > IGMP or PIM messages. But many NVEs (server based virtual switches) don’t > terminate IGMP nor PIM. Well if the virtual switch supports LISP, then the app directly tells the xTR which groups it is joining. And if the LISP xTR is one-hop northbound from the virtual switch, you can bet the virtual switch does IGMP snooping. > Therefore, NVO3 needs a simpler scheme for “Receiver NVEs”. > draft-ghanwani-nvo3-app-mcast-framework-00 suggests all IGMP messages are > sent to “multicast server”. That is not simpler - that adds a new component to the network. And if you IGMP to a server why is that different than registering to a map-server. But since there is no precise serial spec'ed on how the NVE-to-NVA protocol works no one can tell what can be leveraged for multicast. LISP-signal-free-multicast works because the LISP mapping system protocols are well specified, implemented, and deployed. > Or “Multicast server” can fake “IGMP query” to all the NVEs, which forwarded > down to applications. The reply (IGMP report) can be automatically sent back > to “multicast server” without NVE doing anything extra. > > What do you think? You want multicast routers to attach to the overlay. They don't send IGMP packets to each other. IGMP is a host-to-router protocol and has been abused to be a host-to-switch protocol. Let's stop the abuse. :-) Dino > > > Linda >
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