Subject: [Megaco] ipnapt package

From: "Muhammad Abid" <[email-masked]>
Date: Wed, 14 Feb 2007 22:26:56 -0800

Dear experts,

I need your assistance in understanding the Latching/Re-latching functions.

Per H.248.37 (p5),
When the NAPT Processing signal (ipnapt/latch) with parameter (napt) is sent
to a termination/stream is set to OFF
or the signal is NOT sent then as per default H.248.1 behaviour the MG
will use the IP address and port defined in the RemoteDescriptor for that
termination/stream for the sent application data streams."

If I read it right, I conclude that if NAT(ing) is not required, then no
need to Latch.
However, if NAT(ing) is required/desired then Latching is necessary.

Am I on the right track with the following combinations:

No NAPT .. No Latch
Yes to NAPT ... Yes to Latch

Secondly, how do we handle Latching for an end-office that is multi-homed
(with multiple IP Addresses)

Regards,

Muhammad
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From: [email-masked]
Date: Thu, 15 Feb 2007 08:09:19 +0100

Muhammad,

1) ipnapt package is currently under extension for more semantical
clarifications, see Draft H.248.37 Amendment 1:

http://ftp3.itu.int/av-arch/avc-site/2005-2008/0703_She/AVD-2954.zip
AVD-2954 3 Updated draft new ITU-T Recommendation H.248.37 Amendment 1 "IP
NAPT traversal package: Semantical clarification and address reporting
package" (Ed. 0.5)

2) napt value 'OFF' is required to disable the latching mode, or to
indicate at all that for that Termination isn't NAPT traversal support
required.
Of course, the general use case is NAPT traversal support, then 'LATCH'
mode ...

3) multi-homed IP hosts:
This is basically no issue from ipnapt package point of view. Guess you
consider the case that the host is choosing one out of N IP interfaces for
the session. Right? (The IP interface would be then static for the whole
lifetime of the H.248 stream/termination.)

The case, that the host is changeing IP interfaces *during* an active
session, was also already raised on the list. But I think this case is out
of scope of ipnapt/1.
We plan the submission of a correspondent contribution to the next Q3/16
meeting:

AVD-2974 3 H.248.37 Amendment 1 ? Progress on § 5.6 on Latching modes
Alcatel-Lucent
AVD-2975 3 H.248.37 Amendment 1 ? Progress on § 6 on Address Reporting
package Alcatel-Lucent
AVD-2976 3 H.248.37 Amendment 1 ? Update of Scope text Alcatel-Lucent
AVD-2977 3 H.248.37 Amendment 1 ? Frequent IP port changes as a security
means of VoIP terminals (Living list item #1.b) Alcatel-Lucent 　 AVD-2978
3 H.248.37 Amendment 1 ? Impact of SDP-signalled source filtering according
RFC 4570 (Living list item #1.e)

- Albrecht

                      "Muhammad Abid"                                                                                                
                      <[email-masked]         To:      [email-masked]                                                              
                      m>                       cc:                                                                                   
                                               Subject: [Megaco] ipnapt package                                                      
                      15.02.2007 07:26                                                                                               

Dear experts,

Per H.248.37 (p5),
When the NAPT Processing signal (ipnapt/latch) with parameter (napt) is
sent to a termination/stream is set to OFF
or the signal is NOT sent then as per default H.248.1 behaviour the MG
will use the IP address and port defined in the RemoteDescriptor for that
termination/stream for the sent application data streams."

No NAPT .. No Latch

Regards,

Muhammad_______________________________________________
Megaco mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/megaco

---

From: "Muhammad Abid" <[email-masked]>
Date: Thu, 15 Feb 2007 09:13:06 -0800

Alobrecht,

Many thanks for clarification and prompt reply.

Muhammad