Subject: [Ietf-behave] multicast question

From: Cullen Jennings <[email-masked]>
Date: Mon, 25 Oct 2004 06:07:37 -0700 (PDT)

If a NAT did nothing but take IGMP packets from inside and sent them to
outside with no modification, and it took all traffic to a multicast address
from the outside and forwarded it to inside interface with no modification,
would it meet the requirements of this draft?

Cullen

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From: "Dan Wing" <[email-masked]>
Date: Mon, 25 Oct 2004 09:43:55 -0700 (PDT)

> outside with no modification, 

The source IP address would be wrong, as it would be the RFC1918 address.

Requirement 4.2 in the I-D states the outgoing packet must have the NAT's 
public IP address:

  4.2  IGMP Packets Sent Towards WAN Interface

   The IGMP packets sent by the NAT MUST follow the requirements in
   RFC3376 section 4 [3], specificially the TTL MUST be 1, IP precedence
   MUST be Internetwork Control (Type of Service 0xc0), and it MUST
   carry the IP Router Alert option.

   The IGMP packets sent by the NAT towards the WAN MUST use the NAT's
   public IP address as the source IP address.

> and it took all traffic to a multicast address

That part is fine.  The draft requires handling the multicast 
packets in that fashion.

> would it meet the requirements of this draft?

-d