Re: IP changeover Procedures

Hi Akhil,
 
A change of address for the MGC implies a new control association.  That does not necessarily mean that any contexts will be altered; all it means is that the control association has undergone a change.  It is up to the MGC to clean up anything on the MG that is out-of-whack.  Given that this is really the same MGC (though the MG cannot possibly know that), the MGC can choose to take NO action and continue everything as it is.  I will note that the change of interface will take a non-zero amount of time, so there is the possibility that messages will be lost.  The spec is pretty clear that the MG has to send replies back to where the command came from, so there is no way that a change of IP address can not result in a change of association (see H.248.1, Clause 9).
 
There is no way the MG could know that the MGC is the same one after the change of interfaces.  Please see H.248.1 Annex F for normative details on the ServiceChange procedures that are then used in the overall procedures in Supplement 7.
 
Kevin



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From: [email protected] [mailto:[email protected]] On Behalf Of Akhil Jain
Sent: Wednesday, November 18, 2009 5:30 AM
To: [email protected]
Subject: [Megaco] IP changeover Procedures



Hi All, 


Per our Implementation, we need to provide Interface Redundancy at MGC end, the architecture we were going to implement is MGC-Active will have 2 IP interfaces and MGC-Standby will have 2 IP interfaces.Can someone help in answering following things:

1. If an Association has been established between MGC-Active (IP1) and peer MG, and now IP1 of MGC-Active has gone down and IP-2 of MGC-Active needs to takeover without breaking the current control association how can we achieve that? 
<<< Per "Updated Draft ITU-T H.Sup7 “Gateway Control Protocol: Establishment Procedures for the H.248 MGC-MG Control Association” (Ed. 0.14)" ServiceChangeAddress field can be used by MGC to tell new IP address for remaining association. But the document has suggested the use of Service Change Address field in the "Association Establishment Phase".
Another thing if MGC sends ServiceChangeMethod as "Handoff" then It would mean that MGC wants a new association but that is not the case, MGC only wants to change the address for rest of the association. >>>


2. If we use MGCIDtotry field in the ServiceChange command then MGC will send this command through IP2 (as IP1 of MGC has been down) so, how will MG got to know that this request has been sent by MGC that has been registered on IP1. Shall it recognizes the MGC via MID ?


Kindly help!


Thanks
Akhil Jain

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