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

On Jun 6, 2007, at 1:01 PM, Brian Haberman wrote:

>
>
> Marshall Eubanks wrote:
>
>>>>>>
>>>>>>
>>>>>> 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.
>>>
>>
>> This has to be supported IMHO.
>>
>
> But it could be supported by having an administrator inside the NAPT
> assign different groups to all the SSM senders.  That way, (S,G)
> collisions will not occur outside the NAPT.
>
> I don't see an easy, automated solution.

The NAPT knows what is SSM. Couldn't it also do a Multicast Group  
Translation for SSM groups ? Why
is this more difficult than, say, port translation ?

Marshall


>
> Regards,
> Brian