All things related to multicast

[Tom Pusateri <>]

In message 
<>
 you write:
>>> If the header length of the dummy IP header is set,
>
>    What do you mean by set? It should be set to 20, no? Are you saying your
>    definition of a dummy IP header is one with a Total Length field of 0?

The spec doesn't say that it should be set to 20 or any other value.
In fact, it only specifies that the group, source, and data length
be set. The other fields are not specified in the spec. The data length
should be set to zero it says.

>>> You know its IP version number from the outer IP header.
>
>    That isn't speced anywhere. What if the outer header was IPv4 and the
>    register was for an IPv6 multicast packet?

That is possible. We would not handle this correctly today.

>>> This does leave the Group/Source exposed since there is no checksum
>>> covering it.
>
>    Right.
>
>Dino
>

So it seems that the pim working group should update the spec
to more clearly specify which fields get set in a "dummy ip header"
of a null register.

I'll add it to the agenda.

Thanks,
Tom