Subject: doubts on SDP

From: "Sasitharan R" <[email-masked]>
Date: Wed, 18 Apr 2001 19:07:33 +0530

Hi all,

    My understanding on the usage of SDP is as follows,

1) Media gateway controller (MGC) uses SDP to get the session description
and properties of terminations from
    mediagateway(MG). So when MGC initiates any command it uses the values
given by SDP. If we use SDP MG
    will give values as fully specified to MG. This is my understanding. Is
it correct? If I'm wrong please explain how it will be?

2)  If we design a residential gateway using MGCP and MEGACO, can we do this
without having SDP ?
     Is SDP is a mandatory for any MG ?

3)  Is it possible to change a Residential gateway to trunking Gateway ? If
so is only signaling is the addition ?

     Any body in this mailing list are invited to clarify my doubts.

Regards and
thanks in advance,
    sasi

---

From: "Madhu Babu Brahmanapally" <[email-masked]>
Date: Wed, 18 Apr 2001 10:02:01 -0400

Hi Sasi,
My answers below with [Madhu]
Regards
Madhubabu
-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Sasitharan R
Sent: Wednesday, April 18, 2001 9:38 AM
To: [email-masked]
Subject: doubts on SDP

Hi all,

1) Media gateway controller (MGC) uses SDP to get the session description
and properties of terminations from
    mediagateway(MG). So when MGC initiates any command it uses the values
given by SDP. If we use SDP MG
    will give values as fully specified to MG. This is my understanding. Is
it correct? If I'm wrong please explain how it will be?
[Madhu] The MGC can either fully specify, over specify or underspecify the
values in different fields of SDP. If underspecified, MG has to specify the
value it has chosen and send the chosen values in the response. If the MGC
fully specify, then the MG should validate the support for the specified
parameters and then respond accordingly.

2)  If we design a residential gateway using MGCP and MEGACO, can we do this
without having SDP ?
     Is SDP is a mandatory for any MG ?
[Madhu] SDP is a mandatory means of exchanging the session description in
both MGCP and MEGACO. You have to live with that.

3)  Is it possible to change a Residential gateway to trunking Gateway ? If
so is only signaling is the addition ?
[Madhu] IMO the packages supported on the Media Gateway decides the behavior
of the Gateway. This in turn means that the commands exchanged between the
MG and MGC decides the operation taken at the MG. The MG and MGC should be
aware of the behavior of the terminations in the Media Gateway(whether it is
RG or TGW). It is definitely possible to change a Residential gateway to
Trunking gateway.

Regards and
thanks in advance,
    sasi

---

From: Christian Groves <[email-masked]>
Date: Fri, 27 Apr 2001 16:12:59 +1000

Hello Sasi,

You may design a MG that implements H.248 without SDP by using the
binary version of Megaco as it does not use SDP for description in the
Local and remote descriptors.

Cheers, Christian