PDU & ASN parser

[Sherlock, Stuart]

Would someone please unsubscribe me.

Thanks
Stuart Sherlock

                -----Original Message-----
                From:   Paul Long [mailto:Plong at SMITHMICRO.COM]
                Sent:   Wednesday, June 30, 1999 9:28 AM
                To:     ITU-SG16 at MAILBAG.INTEL.COM
                Subject:        Re: PDU & ASN parser

                Guntram,

                I raised this issue over a year ago. In addition, H.225.0
does not address
                this issue regarding RAS (it does regarding call signaling),
so I suppose one
                could pack multiple RAS messages per unreliable-transport
PDU. As you say, it
                doesn't make sense to pack messages, and I don't think
anyone does it. We
                should probably add something like the following to section
6.1 of the next
                revision of H.225.0.

                "When messages are sent on the H.225.0 RAS channel, only one
whole message
                shall be sent within the boundaries defined by the
transport; there shall be
                no fragmentation of H.225.0 RAS messages across transport
PDUs."

                We should also insert the indicated text, below, into
existing text in the
                same section.

                "When messages are sent on the reliable H.245 control
channel, >>>exactly one
                message should be sent but<<< more than one message may be
sent within the
                boundaries defined by the reliable transport PDU as long as
whole messages are
                sent;"

                Paul Long
                Smith Micro Software, Inc.

                        -----Original Message-----
                        From:   Guntram Diehl [SMTP:gdiehl at innovaphone.com]
                        Sent:   Wednesday, June 30, 1999 4:14 AM
                        To:     'Bancroft Scott'; 'Srikanth Nayani'
                        Cc:     'h323implementors at imtc.org'
                        Subject:        RE: PDU & ASN parser

                        Yes this can be done, but does any implementation
actually do it? Why
                        would anyone want to do this, it just saves 4 bytes
tpkt header per
                        additional H.245 message and it does not change the
fragmentation of
                the
                        whole thing by IP.

                        Or is there another reason why this was specified in
the standard this
                        way?

                        Guntram

                        -----Original Message-----
                        From: Bancroft Scott [mailto:baos at OSS.COM]
                        Sent: Wednesday, June 30, 1999 3:54 AM
                        To: Srikanth Nayani
                        Cc: h323implementors at imtc.org
                        Subject: Re: PDU & ASN parser


                        On Tue, 29 Jun 1999, Srikanth Nayani wrote:

                        >   In the H.225 document  chapter 6 mentions that
multiple messages
                can be
                        > sent over the reliable H.245 control channel
within the boundaries
                of the
                        > reliable transport channel . Does that mean that
two H.245 PDUs
                encoded
                        > using PER and whose total encoded length is within
the boundary of
                the
                        > H.245 TCP channel can be merely concatenated and
sent as  a single
                payload
                        > of the H.245 TCP channel.
                        >               If so how does a ASN.1 decoder know
that there are two
                messages in the
                        > payload and the offset at which the second message
starts.

                        An PER decoder does not know that there are two
messages in the
                payload.
                        It does know where the first message ends, so the
location of the next
                        message can be derived from this knowledge.



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