March 2001 - sg16-avd - lists.packetizer.com

H.323 Question
by rdhanju 07 Mar '01

07 Mar '01

I have been trying to find the actual ASN coding of the fastStart element in the version 2 of the H.225 setup message without any luck. Any help is appreciated.. Thanks. Roby Dhanju Senior Engineer ipNetFusion Voice 972.761.9271 x 214 Fax 972.761.9067 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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AVD-2063 Document
by Orit Levin 06 Mar '01

06 Mar '01

Hello all! Unfortunately at the last moment I had to cancel my participation in the meeting due to personal reasons. I hope seeing you all next time, though. I am attaching the AVD-2063 "Draft of Annex O" updated version that includes all the material being discussed so far. Please, upload this late contribution to the working sites. If you find time to review it during the meeting, I will be happy to see your comments and thoughts directly or/and in the meeting report. In any case, I would like to renew the discussion during the next meeting starting from this version. Best Regards, Orit Levin Chief Architect RADVision Inc. TEL: 201.529.4300 x 230 FAX:201.529.3516 mailto:orit@radvision.com http://www.radvision.com 575 Corporate Drive Suite 420 Mahwah, NJ 07430

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Re: New comer questions
by Tom-PT Taylor 06 Mar '01

06 Mar '01

You can find it in section D.2 of the Megaco/H.248 specification. > -----Original Message----- > From: Liu, Gary [mailto:gLiu@unispherenetworks.com] > Sent: Monday, March 05, 2001 8:21 AM > To: Taylor, Tom-PT [NORSE:B881:EXCH]; ITU-SG16(a)MAILBAG.INTEL.COM > Subject: RE: New comer questions > > > Is RFC1006 recommended for MEGACO implementation or vendor specific > implementation? > > -----Original Message----- > From: Tom-PT Taylor [mailto:taylor@nortelnetworks.com] > Sent: Sunday, March 04, 2001 3:28 PM > To: Liu, Gary; ITU-SG16(a)MAILBAG.INTEL.COM > Subject: RE: New commer questions > > > > We use the RFC 1006 length specifier to indicate total > message length in > TCP. > > The "ALF" is actually anything but message delimitation -- > not sure how it > got that name. The functions performed by the application are > > -- reliable delivery (aided by Megaco's transaction orientation) > -- sequencing (not much needed in Megaco except in sorting out event > reports) > -- throttling in the face of network congestion. > > > -----Original Message----- > > From: Liu, Gary [ mailto:gLiu@UNISPHERENETWORKS.COM > <mailto:gLiu@UNISPHERENETWORKS.COM> ] > > Sent: Friday, March 02, 2001 11:16 AM > > To: ITU-SG16(a)MAILBAG.INTEL.COM > > Subject: New commer questions > > > > > > Hi, > > > > I am a new commer to the MEGACO mailing list and have some > > dump questions. > > The text enconding is new to me. If TCP is used as > transport, how is a > > transaction message framed out from the data stream. Is > > "MEGACO/1" the frame > > mark? > > The standard requies MGC/MC to support UDP/ALF. UDP is > already message > > based. Why is ALF (application level framing) needed? I > > though the other way > > around. Framing is needed for TCP. Thanks. > > > > > > Gary Liu > > > > Unisphere Networks, Inc. > > < http://www.unispherenetworks.com <http://www.unispherenetworks.com> > > 7800 Congress Ave., Suit 100 > Boca Raton, FL 33487 > T:(561)981-7022, F:(561)981-7001 > > mailto:gliu@unispherenetworks.com <mailto:gliu@unispherenetworks.com> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > For help on this mail list, send "HELP ITU-SG16" in a message to > listserv(a)mailbag.intel.com >

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Gatekeeper-assigned address in RCF
by Francois Audet 06 Mar '01

06 Mar '01

Hi guys, I found a minor mistake in H.225.0v4. It says in 7.9.1 that if no terminalAlias is included in the RRQ, a dialedDigits address may be assigned by the gatekeeper in the RCF terminalAlias. There is no reason to restrict it to a dialedDigits string. The text in 7.9.2 for RCF mentions a terminalAlias field, not a dialedDigits. If we wanted to restrict it to a "phone number", it should be a partyNumber. The original text is as follows: terminalAlias - This optional value is a list of alias addresses, by which other terminals may identify this terminal. This field may be used in addition to or as an alternative to the terminalAliasPattern and supportedPrefixes fields. If the terminalAlias is null, a dialedDigits address may be assigned by the gatekeeper, and included in the RCF. If an email-ID is available for the endpoint, it should be registered. Note that multiple alias addresses may refer to the same transport addresses. All of the endpoint's aliases that it desires to register shall be included in this list unless the additiveRegistration option is specified, in which case the endpoint aliases in an RRQ shall be added to the list of aliases currently registered for the endpoint. It should be changed to: terminalAlias - This optional value is a list of alias addresses, by which other terminals may identify this terminal. This field may be used in addition to or as an alternative to the terminalAliasPattern and supportedPrefixes fields. If the terminalAlias is null, a terminalAlias address may be assigned by the gatekeeper, and included in the RCF. If an email-ID is available for the endpoint, it should be registered. Note that multiple alias addresses may refer to the same transport addresses. All of the endpoint's aliases that it desires to register shall be included in this list unless the additiveRegistration option is specified, in which case the endpoint aliases in an RRQ shall be added to the list of aliases currently registered for the endpoint. Comments? ---- François AUDET, Nortel Networks mailto:audet@nortelnetworks.com <mailto:audet@nortelnetworks.com> , tel:+1 408 495 3756

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Call for Participation: IPtel 2001 workshop
by Henning Schulzrinne 05 Mar '01

05 Mar '01

Call for Participation 2nd IP Telephony Workshop April 2-3, 2001 - Columbia University, New York City http://www.fokus.gmd.de/events/iptel2001/ Objectives ---------- Internet telephony is rapidly evolving from research to design and deployment. The IP Telephony Workshop aims at bringing together researchers, developers, vendors and service providers active in this area and stimulate discussion on innovation, research, implementation, deployment experiences and future directions. Scope & Topics -------------- Original technical articles related to IP telephony will be presented. We received forty papers addressing QoS research (12), service creation and call control (8), firewall/NAT traversal issues (3), conferencing (3), IP interworking with PSTN and wireless (3), QoS testing and measurement (2), instant messaging and presence (2), security (1), administration mechanisms (1), performance analysis (1), etc. Twenty submissions will be accepted, presented and published in the proceedings. Important Dates --------------- Program published March 15th, 2001 Registration deadline March 23rd, 2001 Workshop April 2nd-3rd, 2001 iptel2001 Organizing Committee ------------------------------ Program Chair H. Schulzrinne Columbia University Program Committee M. Arango Sun Microsystems F. Baker Cisco W. Bauerfeld T-Nova G. Bond AT&T Research S. Bradner Harvard University G. Carle GMD FOKUS J. Crowcroft UCL C. Huitema Microsoft G. S. Kuo National Central University, Taiwan J. Kuthan GMD Fokus T. Magedanz IKV++ GmbH W. Marshall AT&T Research D. Medhi University of Missouri-Kansas City D. Oran Cisco J. Ott University of Bremen T. La Porta Bell Labs B. Rosen Marconi J. Rosenberg dynamicsoft H. Sinnreich MCI WorldCom R. Steinmetz Technical University of Darmstadt H. Stüttgen NEC CCRLE W. Wimmreuter Siemens L. Wolf University of Karlsruhe A. Wolisz Technical University of Berlin M. Zitterbart Technical University of Braunschweig Contact Address --------------- Please send all your inquiries regarding iptel2001 to iptel2001(a)egroups.com. Registration ------------ The registration is now open. Participants are asked to register in advance at http://www.fokus.gmd.de/iptel2001/iptel2001/reg/ The registration deadline is March 23rd, 2001. See our registration website for more details. Accommodation ------------- New York city offers many hotels in different price ranges. Our accommodation web page contains pointers to some nearby hotels, however, attendees are responsible for booking their own accommodation. http://www.fokus.gmd.de/events/iptel2001/accommodation/ Exhibition ---------- To demonstrate how research and development become reality there will be an exhibition co-located with the workshop. A limited number of teams from industry as well as from academia and research will be given space to present their software and hardware, both products and prototypes. If you are interested in presenting your products or prototypes at iptel2001, please send an e-mail to iptel2001(a)egroups.com. Please include a short description of what you plan to display and special requirements if you have any. We will provide tables, power strips, Ethernet/802.11b wireless Internet connectivity (no firewall/NAT) and space for your booth if needed. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv(a)mailbag.intel.com

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List of docs
by Pete Cordell 05 Mar '01

05 Mar '01

Couldn't find an up to date list of docs for the meeting, so made up one myself. Seemed churlish to keep it to myself, so I've attached it here. The links should work, but they currently point to the pictel site. If you want to access files from your hard drive, remove the line: <base href... from the HTML file (just use notepad to edit it). (The unzipped links will only work if you have already unzipped the docs!!!) No promises on accuracy!!! Pete. ============================================= Pete Cordell Tech-Know-Ware pete(a)tech-know-ware.com +44 1473 635863 =============================================

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Re: New comer questions
by Liu, Gary 05 Mar '01

05 Mar '01

Is RFC1006 recommended for MEGACO implementation or vendor specific implementation? -----Original Message----- From: Tom-PT Taylor [mailto:taylor@nortelnetworks.com] Sent: Sunday, March 04, 2001 3:28 PM To: Liu, Gary; ITU-SG16(a)MAILBAG.INTEL.COM Subject: RE: New commer questions We use the RFC 1006 length specifier to indicate total message length in TCP. The "ALF" is actually anything but message delimitation -- not sure how it got that name. The functions performed by the application are -- reliable delivery (aided by Megaco's transaction orientation) -- sequencing (not much needed in Megaco except in sorting out event reports) -- throttling in the face of network congestion. > -----Original Message----- > From: Liu, Gary [ mailto:gLiu@UNISPHERENETWORKS.COM <mailto:gLiu@UNISPHERENETWORKS.COM> ] > Sent: Friday, March 02, 2001 11:16 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: New commer questions > > > Hi, > > I am a new commer to the MEGACO mailing list and have some > dump questions. > The text enconding is new to me. If TCP is used as transport, how is a > transaction message framed out from the data stream. Is > "MEGACO/1" the frame > mark? > The standard requies MGC/MC to support UDP/ALF. UDP is already message > based. Why is ALF (application level framing) needed? I > though the other way > around. Framing is needed for TCP. Thanks. > > > Gary Liu > > Unisphere Networks, Inc. > < http://www.unispherenetworks.com <http://www.unispherenetworks.com> > > 7800 Congress Ave., Suit 100 > Boca Raton, FL 33487 > T:(561)981-7022, F:(561)981-7001 > > mailto:gliu@unispherenetworks.com <mailto:gliu@unispherenetworks.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: New commer questions
by Tom-PT Taylor 04 Mar '01

04 Mar '01

We use the RFC 1006 length specifier to indicate total message length in TCP. The "ALF" is actually anything but message delimitation -- not sure how it got that name. The functions performed by the application are -- reliable delivery (aided by Megaco's transaction orientation) -- sequencing (not much needed in Megaco except in sorting out event reports) -- throttling in the face of network congestion. > -----Original Message----- > From: Liu, Gary [mailto:gLiu@UNISPHERENETWORKS.COM] > Sent: Friday, March 02, 2001 11:16 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: New commer questions > > > Hi, > > I am a new commer to the MEGACO mailing list and have some > dump questions. > The text enconding is new to me. If TCP is used as transport, how is a > transaction message framed out from the data stream. Is > "MEGACO/1" the frame > mark? > The standard requies MGC/MC to support UDP/ALF. UDP is already message > based. Why is ALF (application level framing) needed? I > though the other way > around. Framing is needed for TCP. Thanks. > > > Gary Liu > > Unisphere Networks, Inc. > <http://www.unispherenetworks.com> > 7800 Congress Ave., Suit 100 > Boca Raton, FL 33487 > T:(561)981-7022, F:(561)981-7001 > > mailto:gliu@unispherenetworks.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: Protocol version re-negotiation
by Michael Brown 04 Mar '01

04 Mar '01

Nancy, The parameter that would be used is be the ServiceChangeAddress. As far as the assumption that the MGC would be provisioned with the primary and secondary MGs, certainly it could be done that way (and the text in 11.4 does imply this), but I do think that passing the address is an acceptable approach and should certainly be allowed. IMO we don't really need a new method for this. I don't see how adding a new method is more efficient. I still would contend that adding a ServiceChangeReason is sufficient and that it is desirable to do so (at least in V.2). Michael -----Original Message----- From: Nancy Devin [mailto:nancy.devin@alcatel.com] Sent: Tuesday, February 27, 2001 1:07 PM To: Brown, Michael [NC1:GW10:EXCH] Cc: ITU-SG16 Mail List; megaco(a)fore.com Subject: Re: Protocol version re-negotiation Hi Mike, I don't understand why your are talking about passing the address of the secondary MG to the MGC during a Failover. My understanding is that the MGC is configured with both the primary MG address and the secondary MG address (even though I did not find any text on that). If that is not the case then which parameter is used to transmit the address the the MGC. Also, I think the idea of having to Handoff to another MG or Failover to the other MG may not be the most efficient one. If we are to add a new reason then why not also add a new method which would be "VersionNegotiation" Method: VersionNegotiation TerminationID: Root Reason: MG directed change / MGC directed change Description: Sent from the MG to the MGC, the MG initiates a protocol version negotiation. Sent from the MGC to the MG, the MGC initiates a protocol version negotiation. Nancy Michael Brown wrote: > Comments inline. > > Michael > > "Rosen, Brian" wrote: > > > > > > I think you missed one point: "How does a NON-redundant MG > > > upgrade to a > > > new version of the protocol?" > > It comes down, reboots, and comes up again - it's a service affecting > > change. AFAIK, that's the only way today. > > <MB> Yes, if the MG is really Non-redundant there doesn't seem to be an option. > > > > > > > > > Can the MG Failover to itself? Will this cause any problems > > > in the MGC? > > Since that's not a defined option, some MGCs might have a problem. > > <MB> While there is no existing text specifically saying that this is allowed., > there also is none that disallows this behavior. It seems to me that the MGC > should just accept the "new" address for the "secondary" MG and go on. This > would be used when an MG and its mate hide behind a single address for the MGC > <> MG control association. I would think that this could easily be added to the > implementor's guide and I don't think that it should cause problems. > > > > > > > > > > > To allow this requires only a few changes to the text in RFC3015 as > > > follows: > > > Section 7.2.8 ServiceChange > > > Modify text: "6) Failover - sent from MG to MGC to indicate > > > the primary > > > MG is out of service and a secondary is taking over, or to indicate a > > > version negotiation from the MG." > > > Add a Reason: "Version Negotiation" or a more generic "MG Directed > > > Change". > > > Add text: "The MG may initiate a version negotiation with a > > > ServiceChange Command specifying the "Root" for the TerminationID, > > > ServiceChangeMethod equal to Failover and ServiceChangeReason equal to > > > "Version Negotiation"." > > I think that's a scope add, which I for one am reluctant to do. > > If there was a real problem with something we already had, that's one thing, > > but a real feature add, I'm less thrilled about. I'll admit some of the > > things > > we have talked about stray at least close, if not over such a line. Here, > > I think an MG that can do a non-service affecting upgrade which is not > > redundant is pretty unusual these days - I don't mean to discourage folks > > from doing that, but I also don't feel we need changes in semantics (and > > some additional syntax, albeit some IANA registrations) to make it happen, > > it can wait for V2. > > <MB> I'm suppose I'd agree that this propoal is adding a new feature as it would > require a new, IANA registered reason and the associated behavior. I'd say it's > somewhat unfortunate because basically, I don't see problems with the proposed > approach. There is one thing about the approach that bothers me which we might > consider for V2. That is, the use of Failover in this instance seems > inappropriate. The name just seems to imply that a software upgrade is a failure > scenario. I would suggest that it would be nicer to enhance the definition of > Handoff rather than Failover since handoff implies a more graceful transition. > Given the current definitions of Handoff and Failover in version 1, we do have > to live with Failover for now. > > > > > > > > > > > Cheers, > > > Paul > > > > > > "Rosen, Brian" wrote: > > > > > > > > It's unlikely that we will do anything that adds > > > > new features by edits to the implementor's guide. > > > > It's reasonable to have explanatory text in such a > > > > document that is not normative. > > > > > > > > I think you failover, upgrade, and failover back > > > > with this version of the protocol. > > > > > > > > Brian > > > > > > > > > -----Original Message----- > > > > > From: Paul Rheaume [mailto:paul.rheaume@alcatel.com] > > > > > Sent: Thursday, February 22, 2001 1:00 PM > > > > > To: ITU-SG16 Mail List > > > > > Cc: megaco(a)fore.com > > > > > Subject: Re: Protocol version re-negotiation > > > > > > > > > > > > > > > Folks, > > > > > > > > > > Where is the appropriate list to discuss this issue? > > > > > > > > > > We feel that version negotiation and the version upgrade > > > > > process is not > > > > > well specified and needs to be discussed and properly > > > defined at the > > > > > latest in version 2 of the specification. That means > > > looking at this > > > > > very soon. > > > > > > > > > > I think this issue belongs to the next version of the > > > Implementor's > > > > > Guide. > > > > > > > > > > Regards, > > > > > Paul > > > > > > > > > > Nancy Devin wrote: > > > > > > > > > > > > How does a non-redundant MG upgrade to a new > > > > > > Megaco version without affecting service? How > > > > > > does a redundant MG upgrade to a new Megaco > > > > > > version without affecting service? > > > > > > > > > > > > It is mentionned in RFC3015 that Protocol version > > > > > > negotiation can be done at Restart, Failover, and > > > > > > Handoff serviceChanges. It is not mentionned > > > > > > explicitly how version protocol re-negotiation is > > > > > > done after the MG has registered with the MGC. in > > > > > > both situation > > > > > > > > > > > > This could be done in at least two different ways > > > > > > as listed bellow. > > > > > > > > > > > > 1- Protocol version negotiation could be > > > > > > initiated using the Failover serviceChange. A > > > > > > Failover serviceChange with a protocol version > > > > > > would indicate that the MG has been configured > > > > > > with a new H.248 protocol version. Sent from the > > > > > > MG to the MGC, it indicates that the MG has been > > > > > > configured with a new H.248 protocol version. > > > > > > This serviceChange shall not indicate Failure of > > > > > > the working MG. This would require that for > > > > > > non-redundant MGs, both the primary IP address and > > > > > > the secondary IP address be the same. > > > > > > > > > > > > 2- Protocol version negotiation could be > > > > > > intiated using a new serviceChange method: > > > > > > VersionNegotiation (Method 7 of the serviceChange > > > > > > command as defined in RFC3015) This serviceChange > > > > > > would be sent from the MG to the MGC to initiate > > > > > > protocol version initiation. It indicates that > > > > > > the MG has been configured with a new H.248 > > > > > > protocol version. Sent from the MGC to the MG, it > > > > > > indicates that the MGC has been configured with a > > > > > > new H.248 protocol version. > > > > > > > > > > > > Comments please. > > > > > > Nancy > > > > > > > > -- Nancy Devin Software Designer Alcatel 600 March Road, P.O. Box 13600 Kanata, Ontario, Canada K2K 2E6 Telephone: (613) 591-3600 x6897 Fax: (613) 599-3609 Internet: nancy.devin(a)alcatel.com

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

02 Mar '01

Hi All, Following text contains further clarification on encoding rules for NULL ASN.1 data types. This might be useful for implementors in general. thanks Manoj Paul. -----Original Message----- From: Bancroft Scott [mailto:baos@oss.com] Sent: Thursday, March 01, 2001 6:46 PM To: Paul, Manoj Cc: Olivier DUBUISSON; John Larmouth; Jean-Paul LEMAIRE Subject: RE: Interoperability Problems due to Open Type encoding of Null t ypes (fwd) On Thu, 1 Mar 2001, Paul, Manoj wrote: > Hi Bancroft, > > Thanks for your clarification. I now understand outermost value > as a value nested in an Open Type (TYPE-IDENTIFIER.&Type). I actually > began to get into this loop > when i was encoding an "extension addition" as open type (for ex, an > extension addition in a SEQUENCE). For ex > > example ::= SEQUENCE > { > a BOOLEAN, > ..., > b CHOICE > { > b1 NULL, > b2 NULL > } > } > Now when I encode the value of "b", I would apply the rules of Open > Type encoding. I choose one of the Nulls, say b2. Which of the following > you think is a correct encoding: > > 1) Does b2 qualify as an outermost value and since it does not produce any > encode bits, I need to encode a 0x00 octet for it with the bit-fields of > "b", and > then octet align to generate complete encoding. And add this total length > before this octet aligned bit field. > > 2) b and not b2 is the outermost value, and since b generates a > non-empty bit string, we just add pad bits, add length. So no > additional 0x00 octet for b2. 2 is correct. > The above example is closest to what I am trying to understand. The > problem is that clause "10.1.3" does not state definition of > "outermost value". After your clarification, I do understand it as the > value nested in an Open Type. But besides this definition, is there > any other meaning of Outermost value also (like the last embedded > codepoint in an information element which is after the extension > marker). What do you mean by "codepoint" in this context? > My $0.02 is to make the definition of outermost value > explicit in X.691. Your assistance is greatly appreciated. We will either do this, or revise the text to not use the term "outermost value". Bancroft > warm regards > Manoj Paul. > > -----Original Message----- > From: Bancroft Scott [mailto:baos@oss.com] > Sent: Wednesday, February 28, 2001 4:37 PM > To: Paul, Manoj > Cc: Olivier DUBUISSON; John Larmouth; Jean-Paul LEMAIRE > Subject: RE: Interoperability Problems due to Open Type encoding of Null > t ypes (fwd) > > > On Wed, 28 Feb 2001, Paul, Manoj wrote: > > > Hi Bancroft, > > > > A few weeks back there was a discussion on the SG16 mailing > > list about the meaning of Outermost value. You had given the > > clairification on this term with the following example. > > > > > > > > "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. > > > > I have a doubt about this and would highly appreciate if you could > > help me with that. In the example above, I assume that bar is being > > encoded as an Open type value. > > No, not at all as an Open type value. It is being encoded as an outermost > value, which means that after encoding it is padded to be an integral > number of 8 bits long. > > > You mentioned that each type which is directly nested in the Open type > > should be considered as an Outermost value. > > Correct. > > > By that logic, b,v and i should be encoded as per the outermost value > > rules. Is that true? > > > No. b is not directly nested in an open type value. The *contents* > of v is encoded as an outermost value because it is to be nested in > the Open type, v. i is encoded as an outermost value because the rules > for encoding extension additions mandates it. > > > Does that mean that "b" which resuls in a non-empty bit string need to > > be octet aliged? > > No. Indeed, "b" would never be octet aligned because of the extensibility > marker that will always occur immediately in front of it (and because it > is not encoded as an outermost type). > > > In the encoding above, you also mentioned that v should result in > > 0x01, 0x00 octets. But why should we encode the length for v, since it > > is not encoded as an open type itself. > > The *contents* of v is encoded as an outermost type, meaning that it is > padded to an octet boundary. v itself is encoded as an Open type, meaning > that a length is always prefixed to its value (i.e., always prefixed to > its *contents* by virtue of encoding v). > > > Shouldn't it just be 0x00? > > No, not at all. > > Consider the case where you have the following and maybe you will see > the rationale why it was designed this way. Suppose we have: > > ObjSet TYPE-IDENTIFIER ::= {...} > > Bar ::= SEQUENCE { > b TYPE-IDENTIFIER.&id ({ObjSet}), > v TYPE-IDENTIFIER.&Type ({ObjSet}{@b}} > } > > > Zoo ::= SEQUENCE { > j Bar, > k INTEGER > } > > If an implementation did not know all the information objects in ObjSet > (a common occurrence in many types of applications) then it would be > impossible for such a receiving implementation to know how many bytes > to skip over to get to k if v were not encoded with a length prefix. > > > I will really appreciate your help on this since no where this > > clarification is available. > > In my previous email I spelled out the pertinent clauses where the > proper encoding is defined. Which did you find unclear. Your feedback > would be much appreciated so that we can improve the documentation. > > ------------------------------------------------------------------------- > 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

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