January 1999 - sg16-avd - lists.packetizer.com

Re: apc number for moterey meeting
by Sakae OKUBO 25 Jan '99

25 Jan '99

Dear Mr. Kajos, > Please allocate an APC number for changes to H.341 Annexes. APC-1495 has been allocated to your contribution as attached. I indicated the source as Editor, but please advise me if it is otherwise. Best regards, Sakae OKUBO (Mr.) *********************************************************** Waseda Research Center Telecommunications Advancement Organization of Japan (TAO) 5th Floor, Nishi-Waseda Bldg. 1-21-1 Nishi-Waseda, Shinjuku-ku, Tokyo 169-0051 Japan Tel: +81 3 5286 3830 Fax: +81 3 5287 7287 e-mail: okubo(a)giti.or.jp *********************************************************** ---------------------------------------------------------------------- APC- Source Title ---------------------------------------------------------------------- 1486 SG11 Q.20/11 DSS2 protocol provision of adaptive timing recovery used for transmitting clock 1487 SG9 Q.31/9 Progress report on Webcasting 1488 MPEG Liaison statement from SC 29/WG 11 to ITU-T SG 16/Q 11, 12, 13 and 14 on MPEG-4 Systems on H.32X 1489 MPEG Liaison statement from SC 29/WG 11 to ITU-T SG 16/Q11, 12, 13, and 14 on MPEG-4 Audio on H.32X 1490 MPEG Liaison statement from SC 29/WG 11 to ITU-T SG 16/Q12 on Common Text Recommendations 1491 Nokia GSM in H.323 1492 AT&T H.323 Differentiated Services and Their Protocol Architectures 1493 AT&T Viewgraphs presentation for "H.323 Differentiated Services and Their Protocol Architectures" 1494 AT&T TIA/EIA IS-641 Enhanced Full-Rate Speech Codec for H.323 1495 Editor Changes to H.341 Annexes (G Kajos) ----------------------------------------------------------------------

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Monterey meeting - hotel cutoff date and document list
by Sakae OKUBO 25 Jan '99

25 Jan '99

Dear Q.12-14/16 experts, This is to remind you that the hotel reservation cutoff date is Wednesday, 27 January 1999. ftp://standard.pictel.com/avc-site/9902_Mon/Notice_Monterey.txt ftp://standard.pictel.com/avc-site/9902_Mon/Invitation_Monterey.zip Please directly contact Embassy Suites on Monterey Bay using the form included in the host's invitation. Participants are requested to book at the Embassy Suites, as its "conference arrangement" price is very reasonable, paying also for the conference facilities including beverages. Your cooperation helps the meeting host. Attached please find the current list of registered documents for the meeting. Early registration of your documents is requested to justify holding the meeting. Best regards, Sakae OKUBO (Mr.) *********************************************************** Waseda Research Center Telecommunications Advancement Organization of Japan (TAO) 5th Floor, Nishi-Waseda Bldg. 1-21-1 Nishi-Waseda, Shinjuku-ku, Tokyo 169-0051 Japan Tel: +81 3 5286 3830 Fax: +81 3 5287 7287 e-mail: okubo(a)giti.or.jp *********************************************************** ---------------------------------------------------------------------- APC- Source Title ---------------------------------------------------------------------- 1486 SG11 Q.20/11 DSS2 protocol provision of adaptive timing recovery used for transmitting clock 1487 SG9 Q.31/9 Progress report on Webcasting 1488 MPEG Liaison statement from SC 29/WG 11 to ITU-T SG 16/Q 11, 12, 13 and 14 on MPEG-4 Systems on H.32X 1489 MPEG Liaison statement from SC 29/WG 11 to ITU-T SG 16/Q11, 12, 13, and 14 on MPEG-4 Audio on H.32X 1490 MPEG Liaison statement from SC 29/WG 11 to ITU-T SG 16/Q12 on Common Text Recommendations 1491 Nokia GSM in H.323 1492 AT&T H.323 Differentiated Services and Their Protocol Architectures 1493 AT&T Viewgraphs presentation for "H.323 Differentiated Services and Their Protocol Architectures" 1494 AT&T TIA/EIA IS-641 Enhanced Full-Rate Speech Codec for H.323 ----------------------------------------------------------------------

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complete solutions
by MIRRORCOM DUPLICATION 23 Jan '99

23 Jan '99

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Re: Multiple aliases in ARQ destinationInfo
by Santo Wiryaman 23 Jan '99

23 Jan '99

As a GK developer, I share Paul Long's desire to arrive at some concensus on how a GK (or a collection of GK's) should treat multiple aliases in an ARQ. Several suggestions had been offered such as interpretation 1, interpretation 4, interpretation 4 plus Chris' refinements, and so on. Before we define how the GK should interpret multiple aliases, I think we need to find out what the endpoints (or users of those endpoints) mean when they send multiple aliases in a call. In this short email discussion of 4 people, there seemed to be multiple opinions on what this means: 1. Paul Long envisions an endpoint that would send a call request, specifying MULTIPLE aliases to the GK. These aliases match to different systems (e.g. #@work, #@home, cellphone#, fax#, etc.). The GK would find a match to one of these devices and the call would get routed to one of them. 2. Jim Toga envisions an endpoint that would send a call request, specifying MULTIPLE aliases to the GK. These aliases all match to a single device. The GK would find the device and the call would get connected. The two devices would then negotiate what kind of call it is (audio only vs. multimedia) by way of evaluating the aliases in the order they were specified. 3. Chris Purvis suggested an endpoint that would send a call request, specifying MULTIPLE aliases to the GK. The first alias would be the GW of choice. Subsequent alias(es) would contain the address of the "ultimate" destination. 4. Chris Purvis described an endpoint that would send a call request, specifying ONE alias to the GK. This alias is assigned to a person who may be in different places (i.e different endpoints) at different times. S/he somehow notifies the system where to route the call. At the time of the call, the GK would consult a dBase and route the call to the endpoint where the person is. This scenario is not really relevant to the issue at hand because the endpoint sends ONE alias in the ARQ. It is mentioned here to show as an example for how the objectives of scenario 1 can be accomplished without sending multiple aliases. 5. Santo knows of systems out there (MCU's) that register multiple aliases, each corresponding to a conference. Say, MCU1 registers "CONF_A", "CONF_B", "CONF_C" as its aliases. When EP1 calls "CONF_A", the GK would return the address of MCU1. The SETUP from EP1 would later arrive at MCU1 and the destination is "CONF_A". Becuase of this, MCU1 knows that the endpoint wants to joint "CONF_A" and the call is accepted. However, if MCU1 receives a SETUP with multiple destinations such as "CONF_A", "CONF_B", "CONF_C" it might get confused and drop the call (or use interpretation 1 and therefore use the first alias only). This is an example of a potential problems that can result from multiple aliases, not at the GK but at the destination endpoint (e.g. an MCU). I am sure the list above is not comprehensive. If 3 or more people join in the discussion they may have half a dozen more uses for multiple aliases. Some of the multiple alias interpretations (such as #1 - #3 described above) may all have valid and good reasons behind them. Since there can be many interpretations for multiple aliases from the users' point of view (some perhaps conflicting, e.g. #1 conflicts with #3) , it would be hard to specify a rule on the GK which can satisfy all the users' requirement. Some comments to Jim Toga's posting are within the enclosed text. -santo > -----Original Message----- > From: Jim Toga [SMTP:jim.toga@INTEL.COM] > Sent: Friday, January 22, 1999 12:46 PM > To: ITU-SG16(a)mailbag.cps.intel.com > Subject: Re: Multiple aliases in ARQ destinationInfo > > At 10:50 AM 1/22/99 -0500, Santo wrote: > [SNIP] > > >Of course I am not saying that if it hasn't been done it is a bad thing. > I > >am merely suggesting that there may be a better way of doing it (such as > the > >system in the UK described by Chris). It was not a rethoric question > >either; I truly wanted to know if Paul knows of any system out there > where > >you can "blast" dial with multiple numbers and hope to get connected to > one > >of them. > > I would offer as a model both DNS (which allows multiple 'aliases' to > point > to a single host) and 'hunt groups' as mentioned by ChrisP which are very > useful in situations other than call centers. To Chris's point, I also > believe that this functionality should be partially (if not completely) > implemented by a Gatekeeper - the multiple aliases simply gives the GK an > effiecient start. [Santo Wiryaman] The DNS analogy is done today by e.g. an MCU registering multiple aliases for the same CallSignalAddress. Even if a machine has multiple DNS names (aliases) such as in: 140.242.112.1 pj , PaulJ, pJones, Paul_Jones when user applications would "connect" to that system, they would typically use one of them, e.g. : ping pj telnet Paul_Jones.XYZ.com ftp PaulJ What we are dealing here is specifying multiple destinations all at once. It is like saying: ftp m1,m2,m3,m4 Which machine should the system connect to? Perhaps m3 because m1 and m2 are on a different domain? I fully agree with Jim and Chris that routing and hunt-group functionality should be implemented partly if no completely in the GK. I am still having problem seeing how multiple aliases helps the process. Unless, of course the GK is setup to use the same interpretation rules as specified by the site. Then this becomes a site configuration issue doesn't it? Another facet to this is if the aliases have some implied (agreement > between calling and called parties) functionality to them. For example I > might have both and rfc822 alias and an E.164 alias. The implications > might be that they are associated with a multimedia recipient and an > audio-only client respectively. Depending on what the caller wants to do > they might put one 'higher' in the alias array. Note that these are (or > might be) _service_ level capabilities, not the same thing as offered by > H.245.... > > > With respect to 'errror' conditions or inconsistencies on the GK database > when doing look-ups, it seems as though that would really be a policy > issue. The usual behaviour of 'least astonishment' should be the default. > > Comments? > > jimt. > > > > > >I share Chris' concern about such a "blast" dial system which is > >non-determinism. > > > > > > > > >Regards, > > > >-santo > > > >> -----Original Message----- > >> From: Chris Purvis [SMTP:CPurvis@MADGE.COM] > >> Sent: Friday, January 22, 1999 5:33 AM > >> To: ITU-SG16(a)mailbag.cps.intel.com > >> Subject: Re: Multiple aliases in ARQ destinationInfo > >> > >> Time for me to wade in on a couple of points here too, I'm afraid... > >> > >> First let me say what we've implemented so far: > >> 4. Respond with ACF if at least one alias is registered, starting > >> with > >> the first one. > >> > >> Having said that, I'm not certain that's how things should be. I > believe > >> the "right" answer is none of those Paul suggests. My starting point, > >> though, is that at this stage of placing a call, line-hunting is the > job > >> of > >> the gatekeeper, not the endpoint. If one wants to do line-hunting at > the > >> endpoint, one should be sending a number of ARQs - note that there's no > >> reason an endpoint can't have multiple ARQs outstanding at the same > time, > >> so > >> this should not add significantly to call setup latency. > >> Hence what I believe SHOULD happen is that the gatekeeper > >> 1. If it can match anything within its zone, should ensure that > different > >> aliases in the ARQ do not point to different destinations within the > zone. > >> If there is such disagreement, the GK should return ARJ. > >> Either: > >> 2a. Repeat the same policy at any other levels of search that it > engages > >> in > >> (LRQs etc). > >> or (probably "better" from the point of view of call setup times, > although > >> less deterministic): > >> 2b. If a search procedure needs to be done outside of the zone, use the > >> first positive reply you get > >> > >> One use I see for these multiple aliases, is to avoid the abomination > of > >> dial-prefixes for dialing out through gateways. The first alias should > >> point to a gateway (probably by name rather than number), subsequent > >> aliases > >> in a setup message should tell the gateway what to do. Clever > gatekeepers > >> may want to have policy on what outside lines are permitted to certain > >> users, and therefore need to see this information at this stage. > >> Unfortunately nobody seems to use multiple aliases like this... > >> > >> In answer to a couple of other specific points: > >> > >> [Santo] > >> >In practice, could you tell us an example of a widely deployed > >> communication > >> >system where you can "dial" multiple destinations (e.g. home phone, > work > >> >phone, cell phone, fax number, emailID) at once and "it" will get you > the > >> >most suitable destination? I can imagine a smart phonebook/dialer > which > >> >would take the addresses and "dial" one number at a time until it gets > >> >connected. But the smarts is in the application, not in the "switch" > (in > >> >our case the GK). > >> Are you suggesting that if such a thing hasn't been done before it is > not > >> a > >> "good" thing to do? > >> Incidentally the start of such a thing does exist, at least in the UK. > I > >> have friends for whom I can dial a single number. They tell the server > >> for > >> this number where they are at any given time, and when I dial their > >> "personal numebr" I talk to the person, whether they happen to be at > home > >> (on their home number), at work (on their work number) or elsewhere (on > >> their mobile phone). We have a huge opportunity to improve users' > >> experience. > >> > >> [Paul] > >> >Is an EP required to use the exact same alias list in the Setup that > it > >> used > >> >in the ARQ? I don't think so. Sounds like it should use the alias list > >> sent > >> >back in the ACF's destinationInfo field, which would presumably > contain > >> only > >> >the alias(es) that resolved into the provided transport address. Good > >> point, > >> >though. Needs more thought. What if more than one alias resolved into > the > >> same > >> >address and the GK returned all of the resolved aliases? But then, > maybe > >> we're > >> >trying to over-engineer the problem. Maybe it just makes good sense to > >> the > >> >users in these situations to provide a single alias, and everything > just > >> >works... :-) > >> The ACF's destinationInfo field only appears in version 2, but yes this > is > >> certainly what you should use where present (if it's absent, you can't > do > >> anything other than use what you used in the setup message). Do any > >> endpoints complain when they see extra, superfluous aliases in setup > >> messages addressed to them? I doubt it. Even gateways should surely > use > >> what they can make sense of and ignore anything else. The question > mark > >> is > >> how the destinationInfo, destExtraCallInfo and remoteExtensionAddress > >> fields > >> in ACF should be mapped to the various fields in the setup message > >> (CalledPartyNumber, CalledPartySubAddress, destinationAddress, > >> DestExtraCallInfo, remoteExtensionAddress). I seem to remember hearing > at > >> some point that they should be mapped into the fields of the same name, > >> except that the first destinationInfo that is a phone number is moved > into > >> CalledPartyNumber, and CalledPartySubAddress. I believe if implemented > >> this > >> is a potential source of incompatibility with TIPHON however, because > >> (again > >> from memory - no doubt I'll be corrected if I'm wrong!) TIPHON > equipment > >> is > >> instructed to ignore CalledPartyNumber. Whatever "correct" procedure > is, > >> though, it should be agreed and documented. > >> > >> [Paul] > >> >Simple, return the transport address of the first resolved alias. > What's > >> wrong > >> >with that? > >> Possible non-determinism (see 2b above). > >> > >> Regards, > >> Chris > >> -- > >> Dr Chris Purvis - Senior Development Engineer, WAVE CC Software > >> Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks. > >> ENGLAND > >> Phone: +44 1753 661 359 email: cpurvis(a)madge.com > > > +1-503-264-8816(voice) Intel - Hillsboro, OR > mailto:jim.toga@intel.com mailto:james.toga@ties.itu.int > PGP keyID 36 07 86 49 7D 74 DF 57 50 CB BA 32 08 9C 7C 41

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Re: Multiple aliases in ARQ destinationInfo
by Paul Long 22 Jan '99

22 Jan '99

-----Original Message----- From: Jim Toga [SMTP:jim.toga@INTEL.COM] Sent: Friday, January 22, 1999 9:46 AM To: ITU-SG16(a)mailbag.cps.intel.com Subject: Re: Multiple aliases in ARQ destinationInfo With respect to 'errror' conditions or inconsistencies on the GK database when doing look-ups, it seems as though that would really be a policy issue. The usual behaviour of 'least astonishment' should be the default. Comments? I agree that it should be a policy issue. An administrator might not want to delay the call setup by having to look up all aliases in its registration database before responding to an ARQ. I know that one GK vendor I spoke to at the interop had this concern. Plus, what's the danger in not having all aliases resolve to the same transport address? The caller gets a wrong number? Not like that hasn't happened before. I still like good old #4. Paul Long Smith Micro Software, Inc.

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by dawnc＠TOGETHER.NET 22 Jan '99

22 Jan '99

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Re: Multiple aliases in ARQ destinationInfo
by Santo Wiryaman 22 Jan '99

22 Jan '99

Paul, Chris: First, a thank you to Paul for correcting my mistake. You are absolutely right that the extra phone numbers are to be placed in the destExtraCallInfo in the ARQ. I apologise for my lapse of memory and for not double checking the standard. Second, I agree with Chris that a single "number" that can follow a person is a very good thing. In the example that Chris gave, though, the user of the endpoint "dials" a single number. The "network" (in our case the GK) may provide a dBase search on how to route this number at that particular time based on some rules consistent with the service being provided. In this case the ARQ would contain one "number". Of course I am not saying that if it hasn't been done it is a bad thing. I am merely suggesting that there may be a better way of doing it (such as the system in the UK described by Chris). It was not a rethoric question either; I truly wanted to know if Paul knows of any system out there where you can "blast" dial with multiple numbers and hope to get connected to one of them. I share Chris' concern about such a "blast" dial system which is non-determinism. Regards, -santo > -----Original Message----- > From: Chris Purvis [SMTP:CPurvis@MADGE.COM] > Sent: Friday, January 22, 1999 5:33 AM > To: ITU-SG16(a)mailbag.cps.intel.com > Subject: Re: Multiple aliases in ARQ destinationInfo > > Time for me to wade in on a couple of points here too, I'm afraid... > > First let me say what we've implemented so far: > 4. Respond with ACF if at least one alias is registered, starting > with > the first one. > > Having said that, I'm not certain that's how things should be. I believe > the "right" answer is none of those Paul suggests. My starting point, > though, is that at this stage of placing a call, line-hunting is the job > of > the gatekeeper, not the endpoint. If one wants to do line-hunting at the > endpoint, one should be sending a number of ARQs - note that there's no > reason an endpoint can't have multiple ARQs outstanding at the same time, > so > this should not add significantly to call setup latency. > Hence what I believe SHOULD happen is that the gatekeeper > 1. If it can match anything within its zone, should ensure that different > aliases in the ARQ do not point to different destinations within the zone. > If there is such disagreement, the GK should return ARJ. > Either: > 2a. Repeat the same policy at any other levels of search that it engages > in > (LRQs etc). > or (probably "better" from the point of view of call setup times, although > less deterministic): > 2b. If a search procedure needs to be done outside of the zone, use the > first positive reply you get > > One use I see for these multiple aliases, is to avoid the abomination of > dial-prefixes for dialing out through gateways. The first alias should > point to a gateway (probably by name rather than number), subsequent > aliases > in a setup message should tell the gateway what to do. Clever gatekeepers > may want to have policy on what outside lines are permitted to certain > users, and therefore need to see this information at this stage. > Unfortunately nobody seems to use multiple aliases like this... > > In answer to a couple of other specific points: > > [Santo] > >In practice, could you tell us an example of a widely deployed > communication > >system where you can "dial" multiple destinations (e.g. home phone, work > >phone, cell phone, fax number, emailID) at once and "it" will get you the > >most suitable destination? I can imagine a smart phonebook/dialer which > >would take the addresses and "dial" one number at a time until it gets > >connected. But the smarts is in the application, not in the "switch" (in > >our case the GK). > Are you suggesting that if such a thing hasn't been done before it is not > a > "good" thing to do? > Incidentally the start of such a thing does exist, at least in the UK. I > have friends for whom I can dial a single number. They tell the server > for > this number where they are at any given time, and when I dial their > "personal numebr" I talk to the person, whether they happen to be at home > (on their home number), at work (on their work number) or elsewhere (on > their mobile phone). We have a huge opportunity to improve users' > experience. > > [Paul] > >Is an EP required to use the exact same alias list in the Setup that it > used > >in the ARQ? I don't think so. Sounds like it should use the alias list > sent > >back in the ACF's destinationInfo field, which would presumably contain > only > >the alias(es) that resolved into the provided transport address. Good > point, > >though. Needs more thought. What if more than one alias resolved into the > same > >address and the GK returned all of the resolved aliases? But then, maybe > we're > >trying to over-engineer the problem. Maybe it just makes good sense to > the > >users in these situations to provide a single alias, and everything just > >works... :-) > The ACF's destinationInfo field only appears in version 2, but yes this is > certainly what you should use where present (if it's absent, you can't do > anything other than use what you used in the setup message). Do any > endpoints complain when they see extra, superfluous aliases in setup > messages addressed to them? I doubt it. Even gateways should surely use > what they can make sense of and ignore anything else. The question mark > is > how the destinationInfo, destExtraCallInfo and remoteExtensionAddress > fields > in ACF should be mapped to the various fields in the setup message > (CalledPartyNumber, CalledPartySubAddress, destinationAddress, > DestExtraCallInfo, remoteExtensionAddress). I seem to remember hearing at > some point that they should be mapped into the fields of the same name, > except that the first destinationInfo that is a phone number is moved into > CalledPartyNumber, and CalledPartySubAddress. I believe if implemented > this > is a potential source of incompatibility with TIPHON however, because > (again > from memory - no doubt I'll be corrected if I'm wrong!) TIPHON equipment > is > instructed to ignore CalledPartyNumber. Whatever "correct" procedure is, > though, it should be agreed and documented. > > [Paul] > >Simple, return the transport address of the first resolved alias. What's > wrong > >with that? > Possible non-determinism (see 2b above). > > Regards, > Chris > -- > Dr Chris Purvis - Senior Development Engineer, WAVE CC Software > Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks. > ENGLAND > Phone: +44 1753 661 359 email: cpurvis(a)madge.com

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Re: Relationship of H.323 and H.245 versions
by Paul Long 22 Jan '99

22 Jan '99

Chris, In ASN.1-speak, being able to pass an ASN.1 value, typically transparently, is called "relaying" [1]. Luckily, the PER encoding used by both H.245 and H.225.0 are relay-safe [2]. An H.323 entity is therefore technically able [3] to route a message originally encoded using an abstract syntax other than the one it uses itself. Frankly, I don't see how it could be otherwise. Are you saying, for example, that a v4 EP and a v5 EP routed via a v2 GK are both relegated to using v2? Will the GK modify all protocol identifiers to indicate this reduction, or will the EPs continue to think they can use v4 signaling? It's a real shame if the GK becomes the weakest link when there is no normative reason for this. Our stack can support relaying, but then I wrote it myself... :-) Maybe you should have a talk with your stack vendor. [1] 3.8.23/X.691(1994): "relay-safe encoding: A complete encoding of an abstract syntax value which can be decoded (including any embedded encodings) without knowledge of the presentation layer defined context set that formed the environment in which the encoding was performed." [2] 7.3/X.691(1994): "PER encodings are always relay-safe provided the abstract values of the types EXTERNAL, EMBEDDED PDV and CHARACTER STRING are constrained to prevent the carriage of presentation context identifiers." [3] C.2(Non-normative)/X.691(1994): "Where an abstract syntax value contains embedded material that is encoded using a transfer or abstract syntax different from that associated with the abstract syntax value, it is strongly recommended that the embedded material be encoded in a relay-safe manner." Paul Long Smith Micro Software, Inc. -----Original Message----- From: Chris Purvis [SMTP:CPurvis@MADGE.COM] Sent: Friday, January 22, 1999 1:55 AM To: ITU-SG16(a)MAILBAG.INTEL.COM Subject: Re: Relationship of H.323 and H.245 versions Paul, The problem with this is that with the way certain stacks work an application (such as a gatekeeper) can not necessarily get hold of things that weren't fully decoded ASN.1-wise, and therefore can not relay them onwards. What would happen when, for instance, the Madge gatekeeper (H.323v2), received a message from (say) a v4 endpoint containing "new" mandatory fields, is that it would be able to forward only that part of the message which is understood in the (v2) ASN.1 of which it is aware. To do anything different for future versions may or may not be possible (my understanding of PER encoding isn't quite up to being definitive on this) but if it is possible it would require many stack vendors and people with their own stacks to do some significant rewriting. I think Jim's right, much as it would be nice to be cleverer. Chris > -----Original Message----- > From: Paul Long [mailto:Plong@SMITHMICRO.COM] > Sent: 21 January 1999 10:21 > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: Relationship of H.323 and H.245 versions > > > From: Jim Toga [SMTP:jim.toga@INTEL.COM] > This is getting close. One potential > problem surrounds > intermediaries > (for example GKs in a GK-routed call). We > need to indicate > what exactly is > the expected behaviour of 'M' entities when > they get 'N' type > messages > (that look like 'M' messages with extentions.) > > I would contend that the reality of the > situation is that all > we can > stipulate, is that the 'M' entities don't crash in the > presense of 'N' > messages. We can't mandate that 'M's pass new > (uninterpreted/not-understood) data on. > Obviously if there is > an existing > opaque field defined, this _shall_ be forwarded. > > comments? > > I thought I addressed this in the last sentence, "In > addition, if a >product > is relaying an ASN.1 value, it shall encode the same value > that it >decoded, > regardless of its own version or the version of the value's > sender." This is > for intermediate entities such as gatekeepers that relay, or > route, call > signaling and control messages between entities. My company > is not in the > gatekeeper business, so with my lack of familiarity I could > be off base here, > but I believe this statement is necessary to mitigate the > earlier statement, > "Each product shall _encode_ and decode the H.245 and H.225.0 > ASN.1 syntax > trees defined in their respective version of H.323." The last sentence > sanctions, for example, a v1 gatekeeper relaying v2 messages. > I assume this is > a requirement and that we can indeed mandate it. > > Was I not clear, or did I simply not address your concern? > > Paul Long > Smith Micro Software, Inc. >

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Re: Multiple aliases in ARQ destinationInfo
by Paul Long 22 Jan '99

22 Jan '99

-----Original Message----- From: Santo Wiryaman [SMTP:swiryaman@VIDEOSERVER.COM] Sent: Friday, January 22, 1999 7:51 AM To: ITU-SG16(a)mailbag.cps.intel.com Subject: Re: Multiple aliases in ARQ destinationInfo I truly wanted to know if Paul knows of any system out there where you can "blast" dial with multiple numbers and hope to get connected to one of them. No, I don't know of any. I share Chris' concern about such a "blast" dial system which is non-determinism. My primary interest is in raising awareness of this issue among GK vendors. As primarily an EP vendor, we don't want our users to experience the kind of variance in behavior that I experienced at the last interop. My secondary interest is in having a normative or at least consensus-based agreement about what is the right thing to do in light of the ambiguity in the Recommendations. Lastly, I believe that interpretation 4 or possibly Chris' improvement makes the most sense. Paul Long Smith Micro Software, Inc.

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Re: Multiple aliases in ARQ destinationInfo
by Chris Purvis 22 Jan '99

22 Jan '99

Time for me to wade in on a couple of points here too, I'm afraid... First let me say what we've implemented so far: 4. Respond with ACF if at least one alias is registered, starting with the first one. Having said that, I'm not certain that's how things should be. I believe the "right" answer is none of those Paul suggests. My starting point, though, is that at this stage of placing a call, line-hunting is the job of the gatekeeper, not the endpoint. If one wants to do line-hunting at the endpoint, one should be sending a number of ARQs - note that there's no reason an endpoint can't have multiple ARQs outstanding at the same time, so this should not add significantly to call setup latency. Hence what I believe SHOULD happen is that the gatekeeper 1. If it can match anything within its zone, should ensure that different aliases in the ARQ do not point to different destinations within the zone. If there is such disagreement, the GK should return ARJ. Either: 2a. Repeat the same policy at any other levels of search that it engages in (LRQs etc). or (probably "better" from the point of view of call setup times, although less deterministic): 2b. If a search procedure needs to be done outside of the zone, use the first positive reply you get One use I see for these multiple aliases, is to avoid the abomination of dial-prefixes for dialing out through gateways. The first alias should point to a gateway (probably by name rather than number), subsequent aliases in a setup message should tell the gateway what to do. Clever gatekeepers may want to have policy on what outside lines are permitted to certain users, and therefore need to see this information at this stage. Unfortunately nobody seems to use multiple aliases like this... In answer to a couple of other specific points: [Santo] >In practice, could you tell us an example of a widely deployed communication >system where you can "dial" multiple destinations (e.g. home phone, work >phone, cell phone, fax number, emailID) at once and "it" will get you the >most suitable destination? I can imagine a smart phonebook/dialer which >would take the addresses and "dial" one number at a time until it gets >connected. But the smarts is in the application, not in the "switch" (in >our case the GK). Are you suggesting that if such a thing hasn't been done before it is not a "good" thing to do? Incidentally the start of such a thing does exist, at least in the UK. I have friends for whom I can dial a single number. They tell the server for this number where they are at any given time, and when I dial their "personal numebr" I talk to the person, whether they happen to be at home (on their home number), at work (on their work number) or elsewhere (on their mobile phone). We have a huge opportunity to improve users' experience. [Paul] >Is an EP required to use the exact same alias list in the Setup that it used >in the ARQ? I don't think so. Sounds like it should use the alias list sent >back in the ACF's destinationInfo field, which would presumably contain only >the alias(es) that resolved into the provided transport address. Good point, >though. Needs more thought. What if more than one alias resolved into the same >address and the GK returned all of the resolved aliases? But then, maybe we're >trying to over-engineer the problem. Maybe it just makes good sense to the >users in these situations to provide a single alias, and everything just >works... :-) The ACF's destinationInfo field only appears in version 2, but yes this is certainly what you should use where present (if it's absent, you can't do anything other than use what you used in the setup message). Do any endpoints complain when they see extra, superfluous aliases in setup messages addressed to them? I doubt it. Even gateways should surely use what they can make sense of and ignore anything else. The question mark is how the destinationInfo, destExtraCallInfo and remoteExtensionAddress fields in ACF should be mapped to the various fields in the setup message (CalledPartyNumber, CalledPartySubAddress, destinationAddress, DestExtraCallInfo, remoteExtensionAddress). I seem to remember hearing at some point that they should be mapped into the fields of the same name, except that the first destinationInfo that is a phone number is moved into CalledPartyNumber, and CalledPartySubAddress. I believe if implemented this is a potential source of incompatibility with TIPHON however, because (again from memory - no doubt I'll be corrected if I'm wrong!) TIPHON equipment is instructed to ignore CalledPartyNumber. Whatever "correct" procedure is, though, it should be agreed and documented. [Paul] >Simple, return the transport address of the first resolved alias. What's wrong >with that? Possible non-determinism (see 2b above). Regards, Chris -- Dr Chris Purvis - Senior Development Engineer, WAVE CC Software Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks. ENGLAND Phone: +44 1753 661 359 email: cpurvis(a)madge.com

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