Subject: SDP description in MGCP

From: Harpreet Singh Anand <[email-masked]>
Date: Mon, 6 Sep 1999 11:43:43 +0530

Hello all,

There are a few issues regarding usage of SDP in MGCP which are listed below:

1. MGCP v1.* specifies that " If a connection descriptor is requested, but it
does not exist for the connection audited, that connection descriptor will
appear with the SDP protocol version field only." (pp  81 -
<draft-huitema-megaco-mgcp-v1-03.txt>)

It also specifies that "MGCP implementations are expected to be fully capable of
parsing any conformant SDP message, and should send session descriptions that
strictly conform to the SDP standard." (pp 86,
<draft-huitema-megaco-mgcp-v1-03.txt>)

Now, according to SDP, besides version, there are other mandatory fields also,
like  o=  (owner/creator and session identifier),  s=  (session name.) Thus if
an MGCP implementation sends an SDP description only with v=0 field then the
session description is not SDP conformant.

Also, the SDP examples given in the MGCP draft are also not fully SDP conformant
(SDP described madatory fields are missing).

So are we saying that the MGCP implementations will implement only a subset of
SDP as described in MGCP ?

2. MGCP 1.* has specified that multiple SDP descriptions have to be separated by
an empty line. (pp 81, <draft-huitema-megaco-mgcp-v1-03.txt>). However, the
grammer has not been updated to reflect this change. The rules for MGCPCommand
and MGCPResponse should be updated to reflect this change.

Regards,
Harpreet Singh Anand,

Ficon Technology
E-mail :  mailto:[email-masked]
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