[LINK] There goes the neighbourhood...

[Paul Brooks]

On 11/05/2011 6:51 PM, Kim Holburn wrote:
> The main reason NAT is a problem for VOIP/SIP/H323 is that they put IP addresses in the data.  If they relied on IP headers like every sensible protocol designer it would never have been an issue.  You wouldn't need STUN servers or anything else.  Just the packets.  The other fault is that they splatter udp connections with lots of ports.  Not necessary.

However, when the IP addresses that need to be transported around refer to third-party
hosts (i.e. neither of the source or destination hosts of the IP stream) there isn't
really anywhere else to stuff them than inside the data fields being transported. Not
every problem is solved by  a simple bilateral protocol like Telnet.

NAT is a problem because NAT is the problem. Remove the need for NAT as IPv6 allows,
and voila there is no longer any problem with having IP addresses embedded within data
streams, since they no longer have to be munged.

OK, they could have embedded DNS names instead of IP addresses, but at the time small
fixed-length rather than long variable length fields were considered better.

Paul.