[VOIPSEC] 4G Issue Map: signaling complexity

[Simon Horne]

Janne

The principal you described is almost exactly how H.460.18 works for NAT 
traversal. he main differences it the ITU has opted to not force short 
reregistrations but to have a permanently open UDP channel with 0-30sec 
pings to keep the pinhole open. In our work 15sec seemed the optimum ping 
timing which is consistent with what I see you guys doing. Even though the 
standard specifies up to 30sec, from experience, I have found any higher 
than about 25sec may cause the pinhole to close and incoming calls to fail.

Simon



At 03:38 PM 27/08/2006, you wrote:
>No, you do not need to set any external IP address manually this may be
>something special for sipX, I don't know. And you do not need the set a
>re-registration timer on the client this is done on the Ingate only and
>there are two ways to keep the signalling path through the NAT open;
>using short re-registration intervals or sending OPTION packet with
>short intervals. If you use OPTION or re-registration to keep the
>signalling path open is up to the Ingate administrator and depends on
>the clients used. And the user does not need to do any special settings
>on the client and can move between the office and remote sites as they
>want, it is a key feature to make it transparent for the user.
>
>By keeping the signalling path open as described above requests will
>reach the NATed client and media works as long as symmetric RTP is used.