Re: New Internet Draft on automatic (end-user) tunneling for SSM

[Dino Farinacci <dino@procket.com>]

>>          Ross.

    Ross, some quick comments:

    o Indicate the packet format encoding for join and prune messages. If they
      are simply IGMPv3 over UDP, indciate that.
    o Be very clear that the Router-Alert option is used for control packets
      from master to slave. This is what Jeremy freaked on. 
    o Indicate that data packets from the slave to the master do not need to
      be UDP checksummed. Or else, this won't get deployed. Routers doing 
      complete packet checksums in the data path is a non-starter.
    o Be more clear about "data packets from the master are processed like 
      any other multicast packet in the router". This is certaily not true.
      Multicast routers do RPF checks based on incoming interface. Packets
      coming over the UDP tunnel need different handling. And make sure the
      host/master doesn't UDP checksum the packet either.
    o Indicate how TTL and TOS header bits are handled. That is, is the UDP
      tunnel 1-hop or more. And if more than 1, you need a mechanism find out.
    o What is the source IP address of the UDP encapsulated packet forwarded
      by the encapsulating router.
    o And as always with tunnels. How do you propose to deal with MTU issues
      since an additional 28 bytes are added to the data packet.
    o Also, justify why you're not using GRE. 24 bytes of overhead is better
      than 28 plus there are 1000s of deployed routers that support GRE
      tunneling. Some doing it in hardware.

Dino