Meeting documents posted

Paul E. Jones paulej at
Wed Aug 23 20:47:11 EDT 2006

Dear all who kindly responded to my question,

Now I understand the required minimum versions are coming from the 
expected use of H.225.0 generic extensibility framework and H.245 
generic parameter in the NAT traversal mechanism.

9.3	Requirements on Signalling and Media Streams
b)	NAT traversal mechanisms for H.323 multimedia systems shall 
support no less than ITU-T H.323v3, H.245v7, H.225.0v4, and H.235v3. 
All later versions of H.323, H.245, H.225.0 and H.235 may be 

My original difficulty was in the English expression "shall support 
no less than version n." It is negative to "less than n" hence 
equivalent to "n or higher." Furthermore, I understand that version n 
is a super-set of previous version (n-1), at least in principle ..., 
in our standards, meaning that version n entity can interwork with 
any lower version entity. Then the second sentence "may support any 
later version" would be overlapping with the first sentence.

In conclusion, a NAT traversal mechanism with the following H.323 
support conforms to this requirement (not mentioning H.245, H.225.0. 
H.235 for simplicity):

a/ v3
b/ v4
c/ v5
d/ v6
e/ v3, v4         ==> equivalent to b/
f/ v3, v5         ==> equivalent to c/
g/ v3, v6         ==> equivalent to d/
h/ v3, v4, v5     ==> equivalent to c/
i/ v3, v4, v5, v6 ==> equivalent to d/
j/ v4, v5         ==> equivalent to c/
k/ v4, v6         ==> equivalent to d/
l/ v4, v5, v6     ==> equivalent to d/
m/ v5, v6         ==> equivalent to d/

I hope I am correct.

Best regards,

e-mail: okubo at
         (<== sokubo at, valid until 31 March 2007)
Visiting Professor
Global Information and Telecommunication Institute (GITI)
Waseda University
Waseda University, YRP Ichibankan 312        Tel: +81 46 847 5406
3-4 Hikarinooka, Yokosuka-shi, Kanagawa-ken  Fax: +81 46 847 5413
239-0847 Japan
                       H.323 videoconferencing: arranged by advice

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