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H.323 Annex I
by Baese Gero 06 Feb '01

06 Feb '01

Dear Mr. Li, experts, it is quite discouraging that our questions remaining unanswered and the positive signs we were sending are ignored still. We repeated our technical concerns for the UCLA proposal several times. Please be so kind to let everybody know what is needed to implement the proposal. So far provided documents are not sufficient. The simulation scenario document exists for three months now. We were asking you several times to raise your objections for the provided simulation conditions. We were incorporating your favorite test values in the document. What are the reasons to defer the start of the tests still ? The next meeting is approaching and results are needed as basis for the decision. For both of us it would be harmful to fight for details in front of the group again. We are soliciting you to co-operate - it is of mutual interest and the best for the standard. Best Wishes Gero Bäse ----------------------------------------------------------- Gero Bäse Siemens AG Tel.: +49 89 636 53193 Corporate Technology Fax: +49 89 636 52393 Networks and Multimediacommunication CT IC 2 ----------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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Re: Interoperability Problems due to Open Type encoding of Null t ypes (fwd)
by Paul, Manoj 03 Feb '01

03 Feb '01

Hi All, I am resending this mail as there does not seem to be a consensus on the defintion of "outermost" value as defined in X.691 specification. Any additional information which would help solve this issue is appreciated. It will help to mitigate one of the important issues affecting the interoperability across H.323 implementations. thanks Manoj. -----Original Message----- From: Paul, Manoj [mailto:mpaul@TRILLIUM.COM] Sent: Friday, January 19, 2001 10:21 AM To: ITU-SG16(a)mailbag.cps.intel.com Subject: Re: Interoperability Problems due to Open Type encoding of Null t ypes (fwd) Hi Scott, We agree to your interpretation for case (1). However, for case (2) we believe that only Foo SEQUENCE should be considered the outermost value. And since it would not generate an empty bit string, no additional 0x00 octet should be added to the field-list. Why should v (NULL element) also considered as outermost value in this context since it appears within the extension root of Foo, isn't it? -Manoj -----Original Message----- From: Bancroft Scott [mailto:baos@OSS.COM] Sent: Wednesday, January 17, 2001 8:58 PM To: ITU-SG16(a)mailbag.cps.intel.com Subject: Re: Interoperability Problems due to Open Type encoding of Null types (fwd) On Wed, 17 Jan 2001, Manoj Paul wrote: > Experts, > > We have come across a specific problem which has been the root > cause of interoperability failures across different implementations > of H.323 stack. The problem is related to the > 1) Encoding and decoding of NULL data types when they appear as > extension IEs. > 2) Encoding and decoding of extension IEs which have NULL as the > outermost ASN type. > > There have been different interpretations of the PER rules that apply > to the above conditions causing interop failures at encode/decode level. > Although the implementations would encode/decode (1) and (2) according > to Open Type elements, some subtle differences come as mentioned below: > > In case of (1), some implementations would not encode an extra 0x00 > octet for NULL data type and would just encode the length of the open type > element as 0x00. This idea probably stems from the fact that a NULL > data type has no encoding when they appear in the root of the ASN.1 type. > However, as per 10.1.3 and 10.2.1 of X.691, the correct encoding for > such a case would be 0x01 0x00, where 0x01 is the uncosntrained length > of the NULL data type encoding and 0x00 is the value of NULL data type in > extension. Your understanding of the encoding is correct. > In case of (2), some implementations would encode the extension IE as per > it's rules (e.g as a Choice/Sequence etc.), but would not add a 0x00 for > the outermost NULL data type in it's encode tree. This would change the > value of length field to be appended to this open type. Whereas some > implementations do add 0x00 octet for the outermost NULL data type. > > There appears to be a confusion as to what is meant by the "outermost" > value in 10.1.3 of X.691. I would appreciate clarification on this > clause as it would save a lot of interop overhead at encode/decode level. "outermost" value refers to a value of a type that is either directly nested in an open type or is a complete application message unto itself. For example, if you had: Foo ::= SEQUENCE { b BOOLEAN, v TYPE-IDENTIFIER.&Type, ..., i NULL } bar Foo ::= {b TRUE, v NULL : NULL, i NULL} The value of Foo, bar, is an outermost value. The value of v (NULL : NULL) is encoded as an outermost value, so in this case since NULL encodes to 0 bits it is replaced with eight 0-bits, and this is prefixed with a length of 1. Similarly, the value of i is encoded as an outermost value, so the resulting encoding in this case will have a length of 1 followed by eight 0-bits. ------------------------------------------------------------------------- Bancroft Scott Toll Free :1-888-OSS-ASN1 OSS Nokalva International:1-732-302-0750 baos(a)oss.com Tech Support :1-732-302-9669 x-1 1-732-302-9669 x-200 Fax :1-732-302-0023 http://www.oss.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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Re: Interoperability Problems due to Open Type encoding of Null t ypes (fwd)
by Paul, Manoj 02 Feb '01

02 Feb '01

Bancroft: Does your input to ITU-T ASN.1 Meeting defines outermost value as value of a type that is either directly nested in an open type or is a complete application message unto itself. Or does your input refers outermost value only to the value of the open type IE and not the IEs nested within it? Thanks Manoj. On Fri, 2 Feb 2001, Paul E. Jones wrote: > Manoj, > > Given Bancroft's role in the development of ASN.1, I'd say that whatever he > says is probably true and most likely the intent if the text is not clear. I have inputted this to the ASN.1 meeting that was held at the ITU-T in Geneva January 22 - February 2, and this will be clarified in an upcoming corrigendum. > In any case, I would venture to guess that OSS is more widely used than any > other ASN.1 PER encoder/decoder on the market. While it may not be > appropriate to call their tools the "de facto" standard, they very much are > (no disrespect intended to anyone). I would suggest that the text be > clarified according to Bancroft's recommendation and that Implementers > follow his advise, as I believe it would result in the widest possible > interoperability. I'm cc'ing the ITU-T ASN.1 Rapporteur, Olivier Dubuisson, and the ISO/IEC ASN.1 Rapporteur, John Larmouth, in case they have anything to add. Bancroft ______________________________________________________ > > ----- Original Message ----- > From: "Paul, Manoj" <mpaul(a)TRILLIUM.COM> > To: <ITU-SG16(a)mailbag.cps.intel.com> > Sent: Thursday, February 01, 2001 3:34 PM > Subject: Re: Interoperability Problems due to Open Type encoding of Null t > ypes (fwd) > > > > Hi All, > > > > I am resending this mail as there does not seem to be a consensus on > > the defintion of "outermost" value as defined in X.691 specification. > > Any additional information which would help solve this issue is > > appreciated. It will help to mitigate one of the important issues > > affecting the interoperability across H.323 implementations. > > thanks > > Manoj. > > > > -----Original Message----- > > From: Paul, Manoj [mailto:mpaul@TRILLIUM.COM] > > Sent: Friday, January 19, 2001 10:21 AM > > To: ITU-SG16(a)mailbag.cps.intel.com > > Subject: Re: Interoperability Problems due to Open Type encoding of Null > > t ypes (fwd) > > > > > > Hi Scott, > > > > We agree to your interpretation for case (1). However, for case (2) > > we believe that only Foo SEQUENCE should be considered the outermost > > value. And since it would not generate an empty bit string, no additional > > 0x00 octet should be added to the field-list. Why should v (NULL element) > > also considered as outermost value in this context since it appears > > within the extension root of Foo, isn't it? > > -Manoj > > > > -----Original Message----- > > From: Bancroft Scott [mailto:baos@OSS.COM] > > Sent: Wednesday, January 17, 2001 8:58 PM > > To: ITU-SG16(a)mailbag.cps.intel.com > > Subject: Re: Interoperability Problems due to Open Type encoding of Null > > types (fwd) > > > > > > On Wed, 17 Jan 2001, Manoj Paul wrote: > > > > > Experts, > > > > > > We have come across a specific problem which has been the root > > > cause of interoperability failures across different implementations > > > of H.323 stack. The problem is related to the > > > 1) Encoding and decoding of NULL data types when they appear as > > > extension IEs. > > > 2) Encoding and decoding of extension IEs which have NULL as the > > > outermost ASN type. > > > > > > There have been different interpretations of the PER rules that apply > > > to the above conditions causing interop failures at encode/decode level. > > > Although the implementations would encode/decode (1) and (2) according > > > to Open Type elements, some subtle differences come as mentioned below: > > > > > > In case of (1), some implementations would not encode an extra 0x00 > > > octet for NULL data type and would just encode the length of the open > type > > > element as 0x00. This idea probably stems from the fact that a NULL > > > data type has no encoding when they appear in the root of the ASN.1 > type. > > > However, as per 10.1.3 and 10.2.1 of X.691, the correct encoding for > > > such a case would be 0x01 0x00, where 0x01 is the uncosntrained length > > > of the NULL data type encoding and 0x00 is the value of NULL data type > in > > > extension. > > > > Your understanding of the encoding is correct. > > > > > In case of (2), some implementations would encode the extension IE as > per > > > it's rules (e.g as a Choice/Sequence etc.), but would not add a 0x00 for > > > the outermost NULL data type in it's encode tree. This would change the > > > value of length field to be appended to this open type. Whereas some > > > implementations do add 0x00 octet for the outermost NULL data type. > > > > > > There appears to be a confusion as to what is meant by the "outermost" > > > value in 10.1.3 of X.691. I would appreciate clarification on this > > > clause as it would save a lot of interop overhead at encode/decode > level. > > > > "outermost" value refers to a value of a type that is either directly > > nested in an open type or is a complete application message unto itself. > > For example, if you had: > > > > Foo ::= SEQUENCE { > > b BOOLEAN, > > v TYPE-IDENTIFIER.&Type, > > ..., > > i NULL > > } > > > > bar Foo ::= {b TRUE, v NULL : NULL, i NULL} > > > > The value of Foo, bar, is an outermost value. The value of v (NULL : NULL) > > is encoded as an outermost value, so in this case since NULL encodes to 0 > > bits it is replaced with eight 0-bits, and this is prefixed with a length > > of 1. Similarly, the value of i is encoded as an outermost value, so the > > resulting encoding in this case will have a length of 1 followed by eight > > 0-bits. > > > > ------------------------------------------------------------------------- > > Bancroft Scott Toll Free :1-888-OSS-ASN1 > > OSS Nokalva International:1-732-302-0750 > > baos(a)oss.com Tech Support :1-732-302-9669 > > x-1 > > 1-732-302-9669 x-200 Fax :1-732-302-0023 > > http://www.oss.com > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > For help on this mail list, send "HELP ITU-SG16" in a message to > > listserv(a)mailbag.intel.com > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > For help on this mail list, send "HELP ITU-SG16" in a message to > > listserv(a)mailbag.intel.com > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > For help on this mail list, send "HELP ITU-SG16" in a message to > > listserv(a)mailbag.intel.com > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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ARQ/ACF/ARJ between Gatekeepers?
by Frank Derks 02 Feb '01

02 Feb '01

Dear all, since the first version of H.323, the call signalling procedures have been explained through a series of examples. Although examples do help to get the idea on how things should work, they remain examples and are therefore (usually) incomplete. Take the example from Figure2/H.323v2 (or Figure 40/H.323v4): GK1 sends the SETUP message without first initiating the admission control procedure. If GK2 expects the admission control procedure to take place prior to the call setup, then this will fail unless GK2 makes an exception for certain "EPs" (GK1 in this case) to place calls without an admission control procedure. Are there any visions on this scenario? Frank ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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Re: ARQ/ACF/ARJ between Gatekeepers?
by Nagesh Kumar 02 Feb '01

02 Feb '01

Hi! I guess the receiving GK should have a policy to accept calls from other GKs. May be it can have a list of GKs from where it will accept calls. GK will not do ARQ/ACF while contacting the other GK as it may not know that it actaully talking to another GK or to an EP. regards, Nagesh. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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by opera＠localhost.net 01 Feb '01

01 Feb '01

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by ccbat＠GTE.NET 31 Jan '01

31 Jan '01

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H.323 query
by Jan Van Geel 31 Jan '01

31 Jan '01

Hello, I'm new in the domain of H.323 and have a rather basic question. In § 6.4 of H.323 it is stated that communication between gatekeepers is done in an unspecified fashion. Does this mean that there is no standardised protocol for this communication ? If the answer is "indeed there is no protocol defined", is there any common practice ? any comment/help is welcome kind regards Jan Van Geel Signalling Specialist Belgacom /NTS/TPM/NGN Tel : 32 2 202 1035 Email : jan.van.geel(a)belgacom.be **** DISCLAIMER **** "This e-mail and any attachments thereto may contain information which is confidential and/or protected by intellectual property rights and are intended for the sole use of the recipient(s) named above. Any use of the information contained herein (including, but not limited to, total or partial reproduction, communication or distribution in any form) by persons other than the designated recipient(s) is prohibited. If you have received this e-mail in error, please notify the sender either by telephone or by e-mail and delete the material from any computer. Thank you for your cooperation." ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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avd documents
by Agboh, Charles 31 Jan '01

31 Jan '01

Hi, Does anyone know where the AVD documents are uploaded? I can't get access to the standards.pictel.com/avc-site. Best Regards, Charles ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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RE: H.323 Annex I Progress
by Adam Li 30 Jan '01

30 Jan '01

Mr. Jones, Thank you for your email and your concerns. We are trying to make progress on an agreed simulation condition. We just got the response from Mr. Baese on the simulation conditions we sent on 12/21/2000. It appears there are still several controversial issues (please see my other email). It does take quite some time to run the simulation, and we understand the meeting deadline is approaching. We will do our best to work it out with the Siemens team and hope we can resolve the issues and reach an agreement as early as possible. I will keep everyone updated on the progress. If you (or any other interested parties) have any comments on the issues, we would love to hear your opinions and suggestions. Adam Li > -----Original Message----- > From: Paul E. Jones [mailto:paulej@packetizer.com] > Sent: Sunday, January 28, 2001 12:36 PM > To: Baese Gero; adamli(a)ICSL.UCLA.EDU > Subject: Re: H.323 Annex I > > > Mr. Bäse and Mr. Li, > > You will have to refresh my memory on this, but was Mr. Skran's > request that > you produce test results before the meeting in March or produce a > test plan > by that time? > > I would guess that, since I see these postings to the SG16 mailing list, > that little cooperation is taking place between the two sides on Annex I. > Is that an accurate assumption? > > I hope that we can reach some agreements on this before and during that > meeting. I'd like to see some of the scenery in Tasmania :-) > > Paul > > ----- Original Message ----- > From: "Baese Gero" <Gero.X.Baese(a)MCHP.SIEMENS.DE> > To: <ITU-SG16(a)mailbag.cps.intel.com> > Sent: Friday, January 26, 2001 11:18 AM > Subject: H.323 Annex I > > > Dear Mr. Li, experts, > > > as you wished we kindly reviewed your paper. Here are our conclusions: > * it does not incorporate both the conditions used in your > simulation > and the scenario we proposed in APC-1993 correctly > * it does not incorporate the decisions of the group at the Geneva > meeting > * relations to practical usage are missing > To replenish this paper with all the necessary information would take to > long. > > We are running out of time. Therefor we completed APC-1993 with the few > missing values out of your paper. An additional section with the proposed > internet tests is now included. Please be so kind to supplement > this section > with your suggestions. We hope you can finally agree on that > joint scenario > document. Again, it is very important to have a complete scenario > instead of > > a collection of values to make our work tangible for everybody within the > group. > > A few points are still under discussion. Using a rate control for example > does > not make much sense in our case. It is not part of any standard and can be > optimized to support one or the other method. > To regiment the length of slices is only in favour of the UCLA proposal. > Therefore > we don't want to see this restriction within the test scenario. > > It is still impossible to implement the UCLA proposal with the documents > available. > We were asking you several times concerning technical obscurities but your > answer > is still missing. > > We are supposed to use the standard ITU-T code of H.263 for the tests. As > far > as we aware there is no official version including all necessary parts of > H.263. > That is to say only H.26L can be used for the tests. If you know a place > where > the appropriate software is available please provide us with the link. > > Best Wishes > Gero Baese > > ----------------------------------------------------------- > Gero Bäse > Siemens AG Tel.: +49 89 636 53193 > Corporate Technology Fax: +49 89 636 52393 > Networks and Multimediacommunication CT IC 2 > ----------------------------------------------------------- > > > <<APC-1993r2.doc>> > > >

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