Re: RE: [MBONED] FW: WGLC: draft-ietf-behave-multicast-06.txt

Marshall Eubanks wrote:
> Hello;
> 
> On 6/6/07, Brian Haberman <[email protected]> wrote:
>>
>>
>> Alvaro Fernandez wrote:
>> > Brian:
>> >
>> >
>> >
>> > My e-mail was not an answer to Albert, sorry for that,
>> >
>> >
>> >
>> > It is an idea regarding the BEHAVE Internet Draft and how the multicast
>> > NAPT can allow outside multicast routers to uniquely identify different
>> > multicast SSM channels (S,G) coming from inside interfaces in the case
>> > two inside interfaces use the same multicast group.
>> >
>>
>> How prevalent do people expect the scenario of a SSM sender being
>> located behind a NAPT?
>>
> 
> I would expect that this has the potential of being fairly common.
> 
> - Enterprises use NATs a lot. (I am not going to get into the question
> as to whether they should...)
> 
> - Enterprises use multicast video
> 
> - This video needs to go to remote offices, which are commonly behind
> their own NATs.

I assume you mean without utilizing a VPN connection?

> 
> If that multicast moves to SSM then they will need NAT traversal.
> 
> 
>> >
>> >
>> > In the BEHAVE draft, REQ-4, if there is a host on the inside interface
>> > sending UDP packets to a multicast group, the NAPT can change the
>> source
>> > address and the port but not the multicast group address. In this
>> way, I
>> > think the outside routers can not differentiate the two channels
>> because
>> > they have the same source (the public interface) and the same multicast
>> > group address.
>> >
>>
>> Is it possible for the NAPT to have multiple external addresses to use
>> as source addresses?
>>
> 
> Why would it need this ? ASM - (*,G) : SSM (S,G) ?
> Or are you worried about 2 different SSM sources using the same G.
> 

Yes, that is the scenario Alvaro described.  Two senders using the same
G both behind the same NAPT.

Regards,
Brian