Subject: RE: difference between servicechangeaddress and servicechangeMgcI d

From: Lalit Kumar <[email-masked]>
Date: Wed, 20 Jun 2001 12:27:11 +0530

hi,
   Thanks for the response, but some doubts still persist.

   In RFC3015 section 7.2.8, the document writes "The MG may specify an
address in the ServiceChangeAddress parameter of the serviceChange Request,
and the MGC may also do so in the ServiceChange reply. In either case, the
recipient must use the supplied address as the destination for all
subsequent transaction requests within the association......"

   In section 11.5 the document says, "In partial failure, or manual
maintenance reasons, an MGC may wish to direct its controlled MGs to use a
different MGC. To do so, it sends a ServiceChange method to the MG with a
"Handoff" method, and its designated replacement in the
ServiceMgcId............"

   According to my interpretation, besides sending serviceChangeMgcId at the
time of registration, MGC might wish to send the ServiceChange Request with
ServiceChangeMgcId for the mated pair, making transactions transparent to
the MG. All the transaction replies, acks, request or pending shall be
handled by the new MGC after making the new association.

   The MGC might also send a serviceChangeAddress when it wants to handle
all the transaction replies/acks/pendings for transaction request initiated
by it. All the new Transactions shall be handled by the newMG. This setup
works in the current associated and MG need not establish a new association.

  Please correct me if my interpretation is wrong.
	
With Regards,
lalit

-----Original Message-----
From: Madhu Babu Brahmanapally [mailto:[email-masked]]
Sent: Monday, June 18, 2001 7:18 PM
To: 'Lalit Kumar'; [email-masked]
Subject: RE: difference between servicechangeaddress and
servicechangeMgcId

Hi Lalit,
The serviceChangeMgcId is sent from the MGC when it doesn't accept the
registration request from the MG. And hence the serviceChangeMgcId is set to
another MGC. In case the MGC accepts the registration request from the MG,
the serviceChangeAddress is used to specify address to which further
commands/responses need to be sent. Hope this answers your query.
-Regards
Madhubabu

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Lalit Kumar
Sent: Monday, June 18, 2001 2:07 AM
To: [email-masked]
Subject: difference between servicechangeaddress and servicechangeMgcId

hi,
   I was going through RFC3015 section 7.2.8. It says that
    "The ServiceChangeAddress provides an address to be used within the
context of the association currently being negotiated, while the
serviceChangeMgcId provides an alternative address where the MG should seek
to establish another association."

	Can somebody explain the role of association??
	Since both cannot be used simultaneously when should MGC use
serviceChangeAddress and when should it use serviceChangeMgcId??

	Thanks in advance,

With Regards,
lalit

---

From: Terry L Anderson <[email-masked]>
Date: Wed, 20 Jun 2001 10:55:45 -0400

> subsequent transaction requests within the association......"

but you end your quote too soon.  see below.

> handled by the new MGC after making the new association.

But 7.2.8 says,
    "In either case, the recipient must use the supplied address as the
destination for all subsequent transaction requests  within the association.  At
the same time, as indicated in section 9, transaction repies and pending
indications must be sent to the address from which the corresponding requests
originated."

and in second paragraph of section 9
    "As describged in section 7.2.8, either the MG or the MGC may supply an
address in the ServiceChangeAddress parameter to which subsequent request must
be addressed, but responses (including the response to the initial ServiceChange
request) must always be sent back to the address which was the source of the
corresponding request."

and in D.1.5 fourth paragraph (applying to UDP only)
    "...a valid ServiceChange message announcing a failover, it will  start
transmitting outstanding commands to that new MGC. Responses to commands are
still transmitted to the source address of the command."

I think that this is pretty clear that the intent was NOT to make any exceptions
to the principle stated in D.1 (for UDP)
    "Responses must be sent to the address and port from which the corresponding
commands were sent."

>   Please correct me if my interpretation is wrong.

You might prefer a different policy, but I think that the policy in H.248 is
clear - responses always go to source address of request, never to any
advertised address.

--
------------------------------------------------------------
Terry L Anderson              mailto:[email-masked]
Tel:908.582.7013   Fax:908.582.6729
Lucent Technologies/INS/Voice Over IP Access Networks
Rm 2B-121, 600 Mountain Av, Murray Hill, NJ 07974
http://its.lucent.com/~tla (Lucent internal) http://www.gti.net/tla