H.225- CRV

Paul E. Jones paulej at PACKETIZER.COM
Mon Jan 15 23:27:26 EST 2001


(a) is closer to the way things actually work.

Essentially, you can use whatever values you wish so long as you never place
two calls to the same endpoint using the same CRV value.  So, whether two
calls to an endpoint use the same TCP connection or different connections,
the CRV must be unique.

You should also consider the possibility that an endpoint may have two call
signaling addresses.  How would you know if this were the case?  The safest
thing to do is never have two calls with the same CRV at the same time.
However, if you know that the destination endpoints are unique, you could
re-use the CRV value.. at least when a Gatekeeper is not being used.

There are also so other properties of CRVs:
  1) The CRV sent in an ARQ to place a call shall be the same as the
     CRV in the resulting Setup message
  2) The CRV sent in an ARQ to accept a call should *not* be taken
     from the incoming Setup message-- it should be locally generated so
     that it is a unique between the endpoint and the GK


----- Original Message -----
From: "Nehru, Archana" <archie at trillium.com>
To: "'Paul E. Jones'" <paulej at PACKETIZER.COM>
Cc: <ITU-SG16 at mailbag.cps.intel.com>
Sent: Monday, January 15, 2001 10:28 PM
Subject: H.225- CRV

> hi all,
> I have a question about H.323 -CRV values. Q.931 specs says that a CRV
> should be unique per D-channel layer 2 logical link.
> In H.225 context, does the above mean that:
> a) CRV values should be unique across all outgoing H.225 calls that have
> same "destination" IP address ?
> b) CRV value only needs to be unique across all H.225 connections using
> same TCP connection? In other words, if an endpoint A makes two
> calls to endpoint B, then the same CRV can be used on both the calls, as
> long as they use different TCP connections?
> I would appreciate any help on this.
> Regards
> Archana

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