Subject: [Sigtran] Query : Regarding IUA message if the user equipment is unplugged

From: "santosh agarwal" <[email-masked]>
Date: Wed, 4 Dec 2002 18:27:22 -0000

Hello All,

There is a problem whereby the PRI interface takes quite sometime to come up
in case the Interface is unplugged and put back.

In case of the below scenario, how is the IUA  expected to behave..
PBX ---------(e1)-------------SG-----------(iua)-------------MGC

If the PBX is unplugged and put back. Is the User allowed to bring up the
Interface. by sending a Q.921 establish request(SABME)

If The PBX will send a SABME to SG, Does the SG inform the same to the MGC.
Or wait for the MGC to send the IUA_Establish request.( after some user
defined time)
This causes delay since there is no message in GWC to inform that the
interface has gone down.

Thanks for your time ..

Regards
Santosh Agarwal

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Wed, 4 Dec 2002 12:30:40 -0700

Santosh,

santosh agarwal wrote:                                                             (Wed, 04 Dec 2002 18:27:22)
> in case the Interface is unplugged and put back.

Which interface is unplugged?  The E1?  The IUA?

If the E1 is unplugged you should get a DL-RELEASE Indication at the SG side
of the connection which whould be echoed up to the MGC.  The MGC should
continue periodically to attempt a DL-ESTABLISH Request until it is successful
or receives a DL-ESTABLISH Indication (Q.931 requirement).  The PBX should behave
the same (getting DL-RELEASE Indication and attempting to restablish with
DL-ESTABLISH Request).  The link should come back up fairly soon.

What do you mean by some time?  How long does it take to come back up?

If you are talking seconds, realized that it may take several seconds for
the carrier alarms to clear on the E1 when you plug it back in.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

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From: "santosh agarwal" <[email-masked]>
Date: Thu, 5 Dec 2002 10:24:33 -0000

The E1 interface is unplugged from the PBX end..
As per the MGC handling in my case ,, the MGC initiates  a Establish request
after every 2 minutes and it takes
anything between 0 - 2 minutes for the link to come up.

Upon plugging back..
The SG receives a Establish request from the PBX end (Q.921 SABME) but  the
SG doesn't inform  the MGC when a Establish Request. And in turn waits for
the MGC to send the request periodically..

Do we have a mechanism ( like a DL_Establish Indication in Q.921) to inform
the MGC that the far end PBX is now up and
the MGC can initiates a Establish request rather when than waiting for a
predefined timer value..

Regards
Santosh

-----Original Message-----
From: Brian F. G. Bidulock [mailto:[email-masked]]
Sent: 04 December 2002 19:31
To: santosh agarwal
Cc: [email-masked]
Subject: Re: [Sigtran] Query : Regarding IUA message if the user
equipment is unplugged

Santosh,

santosh agarwal wrote:
(Wed, 04 Dec 2002 18:27:22)

If the E1 is unplugged you should get a DL-RELEASE Indication at the SG side
of the connection which whould be echoed up to the MGC.  The MGC should
continue periodically to attempt a DL-ESTABLISH Request until it is
successful
or receives a DL-ESTABLISH Indication (Q.931 requirement).  The PBX should
behave
the same (getting DL-RELEASE Indication and attempting to restablish with
DL-ESTABLISH Request).  The link should come back up fairly soon.

--brian

--
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 5 Dec 2002 04:50:51 -0700

Santosh,

Yes, there is a DL-ESTABLISH Indication in Q.921. (Section 4.1.1.1 Q.921
and elsewhere).  IUA also has an Establish Indication.  The SG should send
Establish Indication to the MGC.

Why is the MGC waiting 2 minutes?

--brian

santosh agarwal wrote:                                                             (Thu, 05 Dec 2002 10:24:33)

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From: "santosh agarwal" <[email-masked]>
Date: Thu, 5 Dec 2002 12:37:44 -0000

Brian,
IUA has a Establish Indication but I am not sure if the specs mention
explicitly that
is should be send by the SG upon receipt of a Q.921 Establish Request.
(Q.921 SABME).
If this is the case than then a Establish request can be triggered by the
MGC upon receipt of
a Establish Indication. And the interface would come up faster rather than
waiting for the next periodic(audit) mechanism to kick it.

MGC is waiting around 0 to 2 minutes since the Audit check all interface
every two minutes and kick a Establish request for interface not in service.

I believe only the Network side (SG-MGC) is allowed to bring up the
interface and the
far end PBX(user) is not allowed to trigger an establish request in case of
IUA.

-- santosh

Santosh,

--brian

santosh agarwal wrote:
(Thu, 05 Dec 2002 10:24:33)
> > There is a problem whereby the PRI interface takes quite sometime to
come
> up

**************************Disclaimer****************************************
********
> whatsoever is strictly prohibited.
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--
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 5 Dec 2002 05:57:33 -0700

santosh,

santosh agarwal wrote:                                                           (Thu, 05 Dec 2002 12:37:44)
> far end PBX(user) is not allowed to trigger an establish request in case of

RFC 3057 Page 22:

	"When the MGC sends an IUA Establish Request message, the MGC MAY
	 start a timer.  This timer would be stopped upon receipt of an IUA
	 Establish Confirm or Establish Indication. ..."

The MGC can clearly receive an Establish Indication.

Although it is not explicitly stated in RFC 3057, test case 2.3.2 in
iua_interop_draft01_oct17.txt shows an Establish Indication being sent from
the SG to the ASP in response to a local DL-ESTABLISH Indication primitive.

The SG should send this primitive when it receives a local DL-ESTABLISH
Indication from the Q.921 interface.

--brian