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Re: [Robustness] Call Clearing related
by Orit Levin 05 Nov '99

05 Nov '99

Hello Paul, Tzvi and all others! Yes, once again I am "in complete agreement with his proposal in Red Bank to strike the text in the current version that allows for the closure of the call signaling channel". This point of view is alignment with (a) in my previous mail. Just to add to it: If we decide to keep in the Standard the possibility to signal an intentional closure of Q.931 logical connection by dropping its TCP connection, we make the future Recovery procedures much more complicated. And I ask everybody on this list: Who knows about H.323 existing commercial implementations that intentionally close Q.931 TCP connection and expect the Call to be kept by the other side? Based on RADVision's internal resources and being participants in all interoperability events, we don't know of any! In regards to (b): Tzvi! To recover from a GK crash (for all types of calls) should be one of the first topics of Robustness Work. There is no question about it!!! My point (b) was that in order to achieve the solution, the "passive" behavior of EP (a sort of implying in the Standard today) would not help. Additional new procedures have to be added to H.323 in the context of Robustness work. Today's Endpoints don't support these future procedures, therefore their passive behavior (or T.O.) will not solve the problem even if the other side supports the new Robustness Procedures. Why passive behavior /T.O. doesn't help: (1) When an application (such as H.323) gets a notification from TCP layer about the failure of specific TCP connection (port+IP), the connection is already closed by the TCP layer. The only way to revive Q.931 connection is to LISTEN for a NEW incoming connection, accept it and somehow (such as by callID) to logically attach the new TCP connection to the old Call. If it had been the only problem in the puzzle (which is not: see (2) below) technically it could have been defined, but it is NOT today. (This is definitely a job for our Robustness group.) Therefore NO H.323v1-3 compliant EP implements such a procedure! (2) The more difficult problem is that upon TCP channel failure, the TPKT connection above gets out of synch. It means that the application layer doesn't know automatically what part of information got lost. In this case, in order to synchronize H.323 Call state between the two sides, application level handshake must be introduced. This is also definitely a job for our Robustness group. Cheers, Orit Levin RADVision Inc. 575 Corporate Drive Suite 420 Mahwah, NJ 07430 Tel: 1 201 529 4300 (230) Fax: 1 201 529 3516 www.radvision.com orit(a)radvision.com

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Re: H323 mobility: Summary of discussion
by Tom-PT Taylor 05 Nov '99

05 Nov '99

I think a basic point in this discussion is that mobility is "bigger than" H.323 and already has well-established architectural underpinnings. It's all very well to talk about an H.323 solution which we could then adapt, but we would more likely end up with an H.323-only solution as a result. The concern then would be whether vendors saw sufficient opportunity in building to this market, compared with the general market for mobility products.

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Re: H323 mobility: Summary of discussion
by Roy, Radhika R, ALARC 05 Nov '99

05 Nov '99

Hi, Tom and All: You might be right. That is why, we need to bring contributions that provide solutions. AT&T has proposed a solution. I think that other companies will also do the same to make the things clear from the conceptual phase to the solution phase. For example, Nortel can also bring contributions along the line that you are envisioning. In the last meeting, Intel brought an interesting proposal too. I guess that Intel might have a product similar to their proposal. That is why, we are discussing whether a separate annex may be good to address that limited scope. We also welcome that any vendors that have products solving mobility in the context of H.323 should bring contributions. Let us see the proposed solutions. It is very difficult to debate in the conceptual phase. That is, the first priority is to bring solutions on the table instead of debating each other in the conceptual phase. My personal feeling is that H.323 has not developed the backend services protocol yet. Once we understand this, we can separate the problems into two parts: 1. The protocol among the H.323 entities (e.g., Terminals, GKs, MCUs, GWs), and 2. The protocol between the H.323 entities and the backend servers. So, there are two step process in H.323 for protocol development. At present, the existing H.323 standard has defined the first protocol only (i.e., protocol among H.323 entities). I see that TD-39 (Security Support for Backend Services and Mobility in H.323) shows a very clever way to define RADIUS as the backend protocol between the GK and BES for security even for mobile users. Similarly, LDAP can also be used as the backend services protocol between the GK and the directory server. So, there are many alternatives to do that. AT&T proposal also recognizes this problem. As a result, the backend protocol between the GK and the HLF/VLF has not yet been defined. We might use any existing protocols between the GK and the HLF/VLF in a similar way what has been proposed in TD-39. Personally, I do not see a problem. By the way, what is HLF/VLF anyway? Is not the user profiles with some alias addresses and some other user defined parameters? What is special about this that we have break the fundamental architecture and protocol of H.323? Hope this email will clarify some of your concerns. Best regards, Radhika R. Roy AT&T > -----Original Message----- > From: Tom-PT Taylor [SMTP:taylor@NORTELNETWORKS.COM] > Sent: Friday, November 05, 1999 11:17 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: H323 mobility: Summary of discussion > > I think a basic point in this discussion is that mobility is "bigger than" > H.323 and already has well-established architectural underpinnings. It's > all very well to talk about an H.323 solution which we could then adapt, > but we would more likely end up with an H.323-only solution as a result. > The concern then would be whether vendors saw sufficient opportunity in > building to this market, compared with the general market for mobility > products. >

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Re: H323 mobility: Summary of discussion
by Roy, Radhika R, ALARC 05 Nov '99

05 Nov '99

> -----Original Message----- > From: Roy, Radhika R, ALARC > Sent: Friday, November 05, 1999 9:12 AM > To: 'Mailing list for parties associated with ITU-T Study Group 16' > Subject: RE: H323 mobility: Summary of discussion > > Hi, Ed and All: > > I do not know whether you have seen my reply to Jaakko. I am enclosing it > again. Please respond to my reply provided Jaakko to prove your statement. > > I completely disagree with Ed. Please also see Marc Roelands's comments on > LA. > > AT&T contribution has shown how H.323 mobility problem can be solved using > home/foreign GK (zone). > > I like to see the complete H.323 mobility problem that has been solved > using the alternative approach as proposed by Nokia. I have NOT seen > Nokia's solution yet. Unless a complete solution is provided like AT&T's, > I am NOT convinced how mobility problem can be solved in a better way. > > I also see that there is a need for HLF/VLF. No one against the HLF/VLF > function. AT&T proposal also has shown how HLF/VLF function is taken > care-of. > > What I disagree with is this: A protocol should NOT be implementation > specific. For example, we do have a luxury to build one protocol for > distributive GK (HLF/VLF) function, one protocol for centralized GK > (HLF/VLF) function or one protocol for hybrid GK (HLF/HLF) function. It is > against the fundamental concept of H.323. For example, the same argument > can also be applied for the directory function. Similar may the case for > other functions as well. It is a complete break down of H.323 protocol and > architecture. > > So, HLF/VLF is another function in H.323. HLF/VLF is NOT a "Holy Grail" > for which we have to create a complete "DISCONTINUITY" in existing H.323 > protocol and architecture. I like see to Nokia's alternate solution to > disprove this fear. > > Nokia has to bring a complete contribution providing solution like AT&T's > to prove their case. Otherwise, we cannot proceed with a concept that has > not proved with a solution. > > The problem can be solved as follows: > > 1. Let Nokia provide a complete proposal solving the H.323 mobility > problem using heir alternative approach. What Nokia has provided is a high > level concept. They have NOT solved the problem yet. Let us see what the > complete solution is. If a solution is provided, we can then compare > Nokia's solution with that of AT&T's solution. Otherwise, their proposal > is still HYPOTHETICAL. It is a concept, NOT a solution. > > 2. How can we agree on a concept without seeing its solution that has the > potential to break down the fundamental architecture of existing H.323 > standard? > > 3. Let us solve H.323 mobility problem within the framework of H.323. > > 4. Let us move on with contributions for the part that we can agree on. If > Nokia brings a complete solution, we will definitely re-consider their > case. > > 5. I agree with you that we also need to work for interworking between > H.323 (IP) mobility and cellular-PSTN/ISDN network. > > Finally, Ed - you have made a statement, but it has to be proved providing > a solution. An alternative concept is there, but we have not seen its > solution yet. What is the problem to bring the alternate solution? Why do > we need to wait for a concept that has NOT been substantiated with a > solution yet? > > Best regards, > Radhika > > -----Original Message----- > From: Edgar Martinez [1] [SMTP:martinze@CIG.MOT.COM] > Sent: Thursday, November 04, 1999 9:47 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: H323mobility: Summary of discussion > Importance: High > > I agreed with most of Jaakko comments and also > make vaild points, and will like to > add the following. > > I believe that the (Home) in Home Zone should be taken out. > What we are talking about is the User's Point of Attached in > any given Zone. The HLF is ready and Data base > which has the User's profile and the current user's location. > We can get a new name to HLF and call it the Location Profile > Register (LPR) or Location Profile Function (LPF). > > I also believe that the (Visited) in Visited Zone sould also > be taken out because again we are talking about > the Users current Point of Attachment in any given Zone. > The VLF has the means to update the > Location Profile Register (LPR) from > any given Zone. We can get a new name to VLF > call it the Location Update Register (LUR) or > Location Update Function (LUF). > > Now we can also support concepts of Zone ID's > such as Current Zone ID and Previous Zone ID. > > Finally, > > And I strongly agree with looking at the interworking > in parallel with H.323 mobility. The time we spent > now looking at interworking will be compensated in the > long run. I sure does working on ISUP, IN and Qsig, inetrworking > with H.323 would agree and we should learn from their experience. > And not leave it for a last minute add-on. > > Lets take the contribution as they come, if one wants to put in > interworking fine. If one wants to put in contributions only H.323 > mobility also fine. Both are in order and within our scope. > > The general strategy should focus on ensuring that the H.323 > Mobility and interworking options are enabled, rather than spending > too much effort blocking alternative options (Our limited resources > frankly don't allow this luxury). But there really is no substitute > for > doing the work - preparing input papers and presenting them > to move things forward. > > Best Regards, > > Ed > Hi, Jaakko: Pl see my reply enclosed below. Best regards, Radhika -----Original Message----- From: Jaakko Sundquist [SMTP:jaakko.sundquist@NOKIA.COM] Sent: Thursday, November 04, 1999 8:48 AM To: ITU-SG16(a)MAILBAG.INTEL.COM Subject: H323mobility: Summary of discussion Hi, Radhika et al, It seems that I did not make all my points so clear in my last message (as I said I was pretty tired when I wrote it). Also the discussion between me and Radhika (& Ed) seems to be getting out of hand. [Roy, Radhika R] Please be happy to take your time. There is no hurry. We have a great responsibility to have the best standard that people can ever collectively think of. So, please provide your best thoughts even if you think that you should need to take rest. Thus I'll try to summarize the points in the discussion and include my views in this message. As I see it, we have been discussing about three basic issues: - The architectural placement of the HLF and VLF functionalities. The discussion also has included (or actually it started from) the question whether the terms: Home Zone and Visited Zone, with respective identifiers should be defined or not. - The two-step approach of first specifying the pure H.323 Mobility and as a second step the issues related to PLMN interworking. The discussion has been on whether (at least some of the) PLMN interworking issues should be considered while working on the pure H.323 Mobility. - The concept of the Location Area (LA). Whether we need that concept or not and if we need it, should it be considered already in the first step (see the above point). I'll address all these points below. THE PLACEMENT OF HLF/VLF AND THE HOME/VISITED ZONE DISCUSSION I think we both/all agree on one thing: The HLF and the VLF must be defined in the standard in such a way that it is possible for multiple GKs to access the same HLF/VLF. This allows for an approach in which the HLF/VLF is distributed among many GKs while simultaneously allowing the HLF/VLF to be associated with only a single GK, if this kind of a centralized design is desired. [Roy, Radhika R] I agree on your first point. To associate HLF/VLF with only a "single" GK is an implementation issue. It is NOT a protocol issue. Here we are mixing between mobility protocol vs. implementation. Let me explain. In H.323, the protocol is GK-centric. So, the mobility protocol should be developed to abide by this fundamental principle. That is, the mobility protocol characteristics should be such that it will not impose any restriction to obtain a service per GK basis. In fact, what you are asking is this: If the HLF/VLF function is associated with a "single" GK, what happens to the mobility protocol. How does the H.323 mobility protocol allow us to have this service. This is a valid question. How do we achieve this goal? Let me answer your question: We will build the protocol in such a way that will NOT restrict this particular implementation. [Roy, Radhika R] To me (as well as to others as well I guess), HLF/VLF is another function that resides behind a GK (similar to functions address and other information). I do NOT see that there is a need to develop a backend protocol between the GK and HLF/VLF right now. In the same token, H.323 has not yet defined the backend protocol between the GK and the directory server. If needed, it may be in the next stage of standardization. However, contributions may be brought to drive this work anytime. [Roy, Radhika R] In fact you might also see AT&T contributions submitted during the development of inter-domain protocol (H.225.0 Annex G). We have shown that the GK architecture can be distributive, centralized (hierarchical), and/or hybrid. Your proposal to associate HLF/VLF with a single GK will create a centralized (hierarchical) GK architectural model. However, H.323 mobility protocol should be robust enough to take care-of all GK architectural models: distributive, centralized (hierarchical), and/or hybrid. [Roy, Radhika R] I guess that I have answered your question. The thing that we disagree on is: I do NOT want to define the terms Home Zone and Visited Zone (or similar) yet. I did not seem to make that clear in my last message. The reasons why I do not want to define this kind of terms, at least yet, are as follows. [Roy, Radhika R] As it mentioned that H.323 is GK-centric. A GK control a zone. To track mobility problem, there should be a point of reference. To make point of reference that is consistent with the H.323 existing architecture, we need to use it without breaking the fundamental concept of H.323. We have to maintain the continuity of the existing H.323 architecture. If we can solve problems with the framework of existing H.323 architecture, why do we need to confuse by creating new terminolgies? I like to see a complete proposal solving all mobility problems (as AT&T and Motorola contributions) justifying the need for creation of new terminolgies as you are proposing. Nokia's contribution proposes some ideas in a high-level manner. What is needed, like AT&T and Motorola contributions, provide a complete solution first. Then, we will compare all solutions together. Otherwise, it is still hypothetical to accept you arguments. The term Home Zone leads in my mind to a definition in which every User is associated with one and only one zone as the User's "Home". I.e. the HLF containing the permanent information about the User can be accessed through the GK of the Home Zone and no other GK. Now, I do not think, Radhika, that this is what you intended, but if we talk about a Home Zone, this is the kind of thing that first comes to my mind. [Roy, Radhika R] Again, in H.323, a use has to register with a GK. It is a MUST. However, a user can also choose some alternate GKs. It is an OPTION. This is the fundamental architectural concept of H.323. We have to start solving our mobility problems based on this foundation. Home GK/Zone concept is based on this foundation to have a reference to start with in order to solve mobility problems. If we can solve H.323 mobility problems based on the basic foundation what already exists in H.323, why do need to invent new terminologies? As I mentioned earlier, like any other functions in H.323, HLF is also another function is obtained by users via the GK. Please note very carefully as I also mentioned in my earlier email: Like address information (e.g., alias, transport/network addresses, etc), HLF function is also obtained via the GK. Now to track the mobility problem, there needs to be a reference point in the context of H.323 architecture. To solve this problem, it is found that it is a better choice to associate a use with a "home" GK because a user, as H.323 requires, must register with a GK. (Please note that there can also be a backend server behind the GK to provide the HLF service. This is another level of standardization. As I explained, similar to the directory service, H.323 also does not need to define this backend protocol right now. However, contributions are welcomed in this area as well.) I currently have the idea that you meant that each User may have multiple Home Zones, is that right, Radhika? If that is the case, I do not fully understand why we would need the concept of the Home Zone at all (but maybe I'm just missing something). [Roy, Radhika R] Again, we have to look into the existing H.323 standard. What does it say? Does it not require that a use must register with a GK? However, there can also be alternate GKs. Using the same basic foundation of H.323, it is logical that a user will register with a GK. To track the mobility, it is a logical choice to have reference point. This GK is designated with a GK known as the home GK. Per existing H.323 standard, a user can also have alternate GKs as an order of priority. In the same token, a user is also free to declare alternate home GKs as an order of priority. AT&T contribution has provided a complete solution how extension of RAS messages will take care-of this problem automatically. In this context, this approach of mobility is perfectly consistent with exiting H.323 standard. The important thing in all these Home/Visited concepts is: how to identify and access the HLF of a certain User and by accessing the HLF, update all the relevant information in the HLF and in the VLFs. [Roy, Radhika R] Not necessarily. HLF/VLF is one of the functions. HLF/VLF may have user profiles in terms of personal IDs and other functions. Personal IDs are nothing but some new alias addresses. So, an extension in "H.323 alias address" will take care-of personal IDs. Similarly, other functions of user profiles can be taken care of with similar extensions. More importantly, home/foreign zone concept helps to solve H.323 mobility problems when users move from one place to another in reference to the H.323 architectural entities (e.g., zones, transport address [TCPs/UDPs: call control, media control, RAS signaling], network addresses [e.g., IP, ATM], domains, etc.). No one should underestimate what the mobility in the context of H.323 means. There are fundamental differences between the so called traditional "plain Vanilla" mobility defining in HLF/VLF in the circuit switching world and the H.323 mobility. Please see AT&T contribution how the complex H.323 mobility problem has been solved simply through extension of RAS messages and some new messages. Please all see Motorola's contribution in this context. If there are multiple Home Zones for a User, all the GKs of these zones can be used to access the HLF of the User, i.e. the HLF is identified by the Home Zone identifier (if this is not the case, what is the purpose of the Home Zone). Now, how is it determined, which GK should be Used in this case? The User must always give some "pointer" with which the HLF can be identified when the User enters a zone (or LA, if we use them). In this case the Home Zone ID would be that identifier. If always one of these Home Zones is given as the access point to the HLF, this leads to a highly centralized model with this one single zone and its GK as the central point. If, on the other hand, any of these zones can be given, how is this zone picked, randomly? Furthermore, how does a GK of a User's Home Zone know that it is in fact a "Home GK" for that User, if the User gives some other Home Zone ID than the one of the Home Zone where he is located? [Roy, Radhika R] Please see my above answer how this complex mobility problems are solved very beautifully in terms of primary GK and alternate GKs in the context of existing H.323 standards. We do NOT need to invent any new terminologies (e.g., location area [LA] or others). Please see AT&T contribution how the complete solution has been provided right within the context of existing H.323 standard. In this context, Motorola's contribution can also been seen. All the above reasons, in my opinion, lead to the fact that the HLF must be identified with an identifier that is NOT related to any single zone or GK. This is why I proposed the concept of Home Domain (I use the concept of an Administrative Domain because, as Radhika mentioned, it is already defined in H.323) in my contribution to the Red Bank meeting (APC-1659). In this case the Home Domain would identify the HLF of a User and thus the GKs in the Home Domain could identify that they are in fact a part of the Home Domain and the HLF to which they have access, is the HLF of the User. If the User would be located in some other (Visited) Domain, his HLF could be identified by the Home Domain (thus this model would be BE centric. The Administrative Domain is, of course, not the only alternative to group the zones, which form the "Home" of a User together, I just used it, because it is already defined. We could also define a HLF Identifier which is not related to a Domain, but the GKs of the zones forming the User's "Home" would recognize if the HLF to which they have access is the correct HLF based on this identifier. [Roy, Radhika R] Both AT&T and Motorola's contributions provide solutions without inventing new terminologies. If needed, as pointed out earlier, we like to see a complete contribution from Nokia that solves all mobility problems using the new terminologies as it is done in AT&T and Motorola's contribution. Otherwise, it is still a very high-level concept such as home/foreign domains. My fear is that it may break the fundamental architectural concept of the existing H.323 standard. So, far I have NOT seen any reason to believe why the solution provided by AT&T complementing the existing H.323 architecture should be modified. I also see that Motorola's contribution is also providing the mobility solution within the framework of existing H.323 architecture. Before, we deviate from the fundamental concept of H.323 architecture, we like to see a complete contribution from Nokia similar to AT&T's. Only then, we will be able to see the merit of Nokia's proposed architectural concept. THE TWO-STEP APPROACH DISCUSSION The two-step approach, as I understand it, means that we will first work on a pure end-to-end H.323 Mobility solution and after that has been done we will define the interworking with legacy (and future) mobile networks. Although I do agree that in general this is a good order to do these two things, I would like to see some general interworking aspects taken into consideration in the first phase. One example of these may be the Location Area concept. I do not want to go into details of the interworking issues in the first step, but I'm afraid that if we do not think about the interworking at all in the first step, we will end up defining some functionalities in two different ways, one being the result of the first step and the other an addition to this as the result of the second step when the solution of the first step is not capable of handling some general interworking procedure, for example. I hope, I made my point clear despite the above text being somewhat rambling... THE LOCATION AREA DISCUSSION This is actually an example of the problem I have with the "strict" two-step approach. Radhika is proposing that we try to solve the mobility in the first step without the LA concept. I think it would be very beneficial, if we at least consider it already in the first step. Furthermore, I am quite sure we will need the concept in the second step, or else we will end up with a very badly scalable system. As I said in my earlier message, the LA concept will help to make the H.323 mobile systems more easily scalable, the price for this is, of course, the increased complexity that the LAs bring to the system. To express shortly, what a LA is for: it is a grouping of NPoAs that are geographically located close to each other. A zone also consists of NPoAs, but these NPoAs can actually be geographically far from each other. In other words, a zone is a set of NPoAs that are grouped together for administrative purposes, not because they are close to each other (which they need not be). When we are dealing with wireless mobile terminals, this grouping based on the geographical location becomes important and thus my opinion is that we should consider the LA concept already in the first phase. [Roy, Radhika R] The network point of attachment has been taken care-of. As I told before, a complete contribution has to be provided how LA concept will be useful to solve the mobility problem. AT&T has provided a complete solution providing architecture, signaling messages, call control, mobility management, and ASN.1 of RAS signaling messages. The contribution has shown how mobility problem is solved in the context of existing H.323 architectural concept. Nokia has to do the same to understand the merit that H.323 mobility problem cannot be solved as it is shown AT&T's contribution without using LA, home/foreign domain concepts as proposed by Nokia. Motorola's contribution can also be seen for this purpose. - Jaakko Sundquist ------------------------------------------------------- In a hole in the ground there lived a hobbit. Not a nasty, dirty, wet hole, filled with the ends of worms and an oozy smell, nor yet a dry, bare, sandy hole with nothing in it to sit down on or to eat: it was a hobbit-hole, and that means comfort. ------------------------------------------------------- > > [Roy, Radhika R] Hi, Jaakko: > > Pl. see my reply provided below. > > Best regards, > Radhika > > -----Original Message----- > From: jaakko.sundquist(a)NOKIA.COM [SMTP:jaakko.sundquist@NOKIA.COM] > Sent: Tuesday, November 02, 1999 11:13 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: H323mobility: meeting > > Once again, hi, Radhika, Ed + all > > See my comments below... > > Hi, Jaakko, Ed, and All: > > I hope that Jaakko will get this mail while he is in > his > office (Thanks > Jaakko - you have reminded us the time difference)! > > [Jaakko:] You caught me just in time. > > > Please note the following: > > 1. Zone and domain are well defined in H.323. > [Jaakko:] Yes, they are defined. > > 2. We have to work for mobility solution in a way > that fits > very well that > already exists in H.323. > > [Jaakko:] Agreed. > > 3. We can invent many things if we need to solve > mobility > problems only when > we think that those functions are NOT covered in > existing > H.323 standard. > > [Jaakko:] Yes. > > 4. If mobility problems can be solved using the > concept of > "zones" and > "domains," I would assume that it would be a big > mile stone > so far the > continuity of H.323 is concerned. That is, as Ed > pointed > out, H.323 mobility > problem is NOT a rocket science. We have to remember > that we > are working in > the framework of already existing H.323 standard > architecture. We have to > relate our solution in the context of existing H.323 > standard. In other > words, we CANNOT change the fundamental concept of > existing > H.323 standards > just because we are addressing mobility. > > [Jaakko:] Yes, of course. I'm not arguing against > that. I > guess you are referring to the Location Area discussion here. The LA > concept > is really merely a scaling issue, you could of course handle paging > (I'm > assuming that we will need the paging procedure) based on zones, > i.e. page > every NPoA in a zone when a call arrives, but this might be quite > limiting > in some cases (the zone may be needlessly big or very small). I do > not think > that we need to change any fundamental concepts of H.323, if we > introduce > the LA concept. > [Roy, Radhika R] May be we can include LA when we see that we need > to optimize a zone further. We may revisit this in the second step. > > 5. I do not understand what benefits we are gaining > adding > more > "terminologies" like "AREA {home, foreign, etc}" > while the > "zone" and > "domain" are already well defined in H.323. My > personal view > is that we > should FIRST try to solve H.323 mobility problems > within the > context of > "zone" and "domain" as far as practicable. I would > argue > that zone and > domain are good enough to serve this purpose for > now. (Pl. > also see AT&T's > and Motorola's contributions.) > > [Jaakko:] As I already said, I did not intent to > define the > terms: home area and visited area. I was just trying to illustrate > the point > I was making about not having the Home/visited zone terms defined > yet. > [Roy, Radhika R] It is good point. Let us define these. AT&T > contributions have the detail definition for each term. > > 6. With respect to your comments that it appears > that every > GK will have HLF > and VLF function, I would say that every GK will > have the > access to the HLF > and VLF function. This capability for each GK has to > be > provided because of > the fact that H.323 architecture is GK-centric. We > do not > have any choice > because we are restricted by the H.323 architecture. > > [Jaakko:] I did not argue against this. The point is > that if > we identify a concept called the Home Zone, this already implies > that each > User has only one zone, in which he/she/it is not a "visiting user". > I think > this would be really restricting. > [Roy, Radhika R] As I mentioned that H.323 is the GK-centric. A > user may change his/her network point of point attachment, but it is still > the same (Home) GK. So, a given (home) GK, there has to be another level > of granularity to address mobility in terms of network point of > attachment. Please see AT&T contribution how home and foreign network > concept have solved the problem. Similar is the case with Motorola's > contribution. The bottom line is that home/foreign GK concept does NOT > imply any restriction to solve H.323 mobility. > > 6.1 With respect to your question whether HLF/VLF > can be > distributive or > centralized, having said (in item 5) that every GK > should > have access to HLF > and VLF function, it is up to implementation whether > HLF and > VLF function > can be centralized or distributive. Please see AT&T > contributions submitted > in Red Bank how we can implement these functions in > both > distributive and > centralized environment. > > [Jaakko:] This is actually quite much the point I > was > making. By defining the Home Zone we would in my mind actually be > pointing > to the centralized model. > [Roy, Radhika R] By definition, there can as many GKs as one wish > have in an H.323 system. So, by definition, the GK-centric H.323 > architecture is distributive. By defining home/foreign GK, H.323 mobility > also becomes distributive up to the point that a basic H.323 system allows > us. So, we do not see any limitations. > > 6.2 In an analogy of this HLF/VLF function, I can > bring > another function - > Directory services. For example, H.323 assumes that > all the > address (e.g., > alias, transport, network) are kept by each GK. > H.323 does > not answer how > the address information is maintained by each GK. > People are > using LDAP > directory server. The question is: whether that > directory > service is > distributive or centralized? I guess that it can be > done in > both ways > depending on implementation. > > [Jaakko:] My point exactly. I would like that all > GKs inside > the same Administrative Domain would be able to access the same > HLF/VLF > functionality. > [Roy, Radhika R] As I pointed out, this an implementation issue. I > would argue that we should allow both options and let an implementor > choose as it is necessary. Please also see AT&T contributions how both > options can be addressed. > > 6.3 In AT&T contribution, it is shown that it better > to make > VLF > distributive (per GK) although HLF function can be > made both > distributive > and centralized. Again, this is a matter of > implementation. > As mentioned in > AT&T contribution, we also need to define a kind of > backend > protocol for VLF > and HLF (something like similar to Siemens, Nokia > and > Intel's contribution - > TD-39: Security Services for Backend Services and > Mobility > in H.323). > > [Jaakko:] I would assume that you can distribute the > HLF/VLF > functionalities inside the Administrative Domain as you like, but > distributing them between the Domains would be difficult. Actually I > think > that the concept of Administrative Domain was introduced in H.323 > for this > kind of reasons. > [Roy, Radhika R] Again, H.323 system is GK-centric in a given > domain. For inter-domain, it is BE-centric. In a given domain, H.323 > architecture has to be GK-centric. Once we solve intra-zone and inter-zone > (intra-domain) mobility, we can extend our experience for inter-domain > problem as well. Please also see AT&T contribution how these problems have > been addressed. My replies to 6.1 and 6.2 are also good for this case. > > 7. Again, I, personally, do not rule our to > re-examine the > benfit of "AREA" > (e.g. location area [LA]) vs. "ZONE/DOMAIN" concept. > May be > it is in the > second step. > > [Jaakko:] I am just a bit afraid that if we leave > this kind > of a major mobility related concept out of the first phase thinking > process, > we will find it much more difficult to include the concept in the > second > phase (where I think we will need it). Furthermore, I'm not > convinced that > the LA concept would not be useful in the pure H.323 approach > either. > [Roy, Radhika R] I think that it can be place holder for now. I > would request to bring more detail contributions proposing solutions like > AT&T and Motorola to prove the case better. Then, we can compare both > solutions. In AT&T contribution, I feel that the LA can be accommodated to > optimize the zone further. So, I do not see that it is a problem to > accommodate the LA concept if needed. I personally prefer that we can > better address this in the second phase once we solve the problem for the > basic architecture. > > Hope that this email will clarify the things better. > > [Jaakko:] I think the main thing is that we got the > discussion going on again. I'm kind of tired already, and I hope > that I > didn't mess things up too much in this mail. > [Roy, Radhika R] Definitely, I also like that discussions must go > on. We must be convinced that we have the best solution because it has the > severe implications for all on-going mobility standard works throughout > the world once we standardize H.323 mobility in SG16. > > Best regards, > Radhika > > Same to you, > Jaakko > -- > Edgar Martinez - Principal Staff Engineer > Email mailto:martinze@cig.mot.com > FAX 1-847-632-3145 - - Voice 1-847-632-5278 > 1501 West Shure Drive, Arlington Hgts. IL 60004 > Public: TIPHON & Other Stds - http://people.itu.int/~emartine/ > Private:TIPHON & Other Stds - http://www.cig.mot.com/~martinze/

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Re: H323 mobility: Summary of discussion
by Roy, Radhika R, ALARC 05 Nov '99

05 Nov '99

Hi, Ed and All: I do not know whether you have seen my reply to Jaakko. I am enclosing it again. Please respond to my reply to provided Jaakko to prove your statement. I completely disagree with Ed. Please also see Marc Roelands's comments on LA. AT&T contribution has shown how H.323 mobility problem can be solved using home/foreign GK (zone). I like to see the complete H.323 mobility problem that has been solved using the alternative approach as proposed by Nokia. I have NOT seen Nokia's solution yet. Unless a complete solution is provided like AT&T's, I am NOT convinced how mobility problem can be solved in a better way. I also see that there is a need for HLF/VLF. No one against the HLF/VLF function. AT&T proposal also has shown how HLF/VLF function is taken care-of. What I disagree with is this: A protocol should NOT be implementation specific. For example, we do have a luxury to build one protocol for distributive GK (HLF/VLF) function, one protocol for centralized GK (HLF/VLF) function or one protocol for hybrid GK (HLF/HLF) function. It is against the fundamental concept of H.323. For example, the same argument can also be applied for the directory function. Similar may the case for other functions as well. It is a complete break down of H.323 protocol and architecture. So, HLF/VLF is another function in H.323. HLF/VLF is NOT a "Holy Grail" for which we have to create a complete "DISCONTINUITY" in existing H.323 protocol and architecture. I like see to Nokia's alternate solution to disprove this fear. Nokia has to bring a complete contribution providing solution like AT&T's to prove their case. Otherwise, we cannot proceed with a concept that has not proved with a solution. The problem can be solved as follows: 1. Let Nokia provide a complete proposal solving the H.323 mobility problem using heir alternative approach. What Nokia has provided is a high level concept. They have NOT solved the problem yet. Let us see what the complete solution is. If a solution is provided, we can then compare Nokia's solution with that of AT&T's solution. Otherwise, their proposal is still HYPOTHETICAL. It is a concept, NOT a solution. 2. How can we agree on a concept without seeing its solution that has the potential to break down the fundamental architecture of existing H.323 standard? 3. Let us solve H.323 mobility problem within the framework of H.323. 4. Let us move on with contributions for the part that we can agree on. If Nokia brings a complete solution, we will definitely re-consider their case. 5. I agree with you that we also need to work for interworking between H.323 (IP) mobility and cellular-PSTN/ISDN network. Finally, Ed - you have made a statement, but it has to be proved providing a solution. An alternative concept is there, but we have not seen its solution yet. What is the problem to bring the alternate solution? Why do we need to wait for a concept that has NOT been substantiated with a solution yet? Best regards, Radhika > -----Original Message----- > From: Edgar Martinez [1] [SMTP:martinze@CIG.MOT.COM] > Sent: Thursday, November 04, 1999 9:47 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: H323mobility: Summary of discussion > Importance: High > > I agreed with most of Jaakko comments and also > make vaild points, and will like to > add the following. > > I believe that the (Home) in Home Zone should be taken out. > What we are talking about is the User's Point of Attached in > any given Zone. The HLF is ready and Data base > which has the User's profile and the current user's location. > We can get a new name to HLF and call it the Location Profile > Register (LPR) or Location Profile Function (LPF). > > I also believe that the (Visited) in Visited Zone sould also > be taken out because again we are talking about > the Users current Point of Attachment in any given Zone. > The VLF has the means to update the > Location Profile Register (LPR) from > any given Zone. We can get a new name to VLF > call it the Location Update Register (LUR) or > Location Update Function (LUF). > > Now we can also support concepts of Zone ID's > such as Current Zone ID and Previous Zone ID. > > Finally, > > And I strongly agree with looking at the interworking > in parallel with H.323 mobility. The time we spent > now looking at interworking will be compensated in the > long run. I sure does working on ISUP, IN and Qsig, inetrworking > with H.323 would agree and we should learn from their experience. > And not leave it for a last minute add-on. > > Lets take the contribution as they come, if one wants to put in > interworking fine. If one wants to put in contributions only H.323 > mobility also fine. Both are in order and within our scope. > > The general strategy should focus on ensuring that the H.323 > Mobility and interworking options are enabled, rather than spending > too much effort blocking alternative options (Our limited resources > frankly don't allow this luxury). But there really is no substitute for > doing the work - preparing input papers and presenting them > to move things forward. > > Best Regards, > > Ed [Roy, Radhika R] Hi, Jaakko: Pl. see my reply provided below. Best regards, Radhika -----Original Message----- From: jaakko.sundquist(a)NOKIA.COM [SMTP:jaakko.sundquist@NOKIA.COM] Sent: Tuesday, November 02, 1999 11:13 AM To: ITU-SG16(a)MAILBAG.INTEL.COM Subject: Re: H323mobility: meeting Once again, hi, Radhika, Ed + all See my comments below... Hi, Jaakko, Ed, and All: I hope that Jaakko will get this mail while he is in his office (Thanks Jaakko - you have reminded us the time difference)! [Jaakko:] You caught me just in time. Please note the following: 1. Zone and domain are well defined in H.323. [Jaakko:] Yes, they are defined. 2. We have to work for mobility solution in a way that fits very well that already exists in H.323. [Jaakko:] Agreed. 3. We can invent many things if we need to solve mobility problems only when we think that those functions are NOT covered in existing H.323 standard. [Jaakko:] Yes. 4. If mobility problems can be solved using the concept of "zones" and "domains," I would assume that it would be a big mile stone so far the continuity of H.323 is concerned. That is, as Ed pointed out, H.323 mobility problem is NOT a rocket science. We have to remember that we are working in the framework of already existing H.323 standard architecture. We have to relate our solution in the context of existing H.323 standard. In other words, we CANNOT change the fundamental concept of existing H.323 standards just because we are addressing mobility. [Jaakko:] Yes, of course. I'm not arguing against that. I guess you are referring to the Location Area discussion here. The LA concept is really merely a scaling issue, you could of course handle paging (I'm assuming that we will need the paging procedure) based on zones, i.e. page every NPoA in a zone when a call arrives, but this might be quite limiting in some cases (the zone may be needlessly big or very small). I do not think that we need to change any fundamental concepts of H.323, if we introduce the LA concept. [Roy, Radhika R] May be we can include LA when we see that we need to optimize a zone further. We may revisit this in the second step. 5. I do not understand what benefits we are gaining adding more "terminologies" like "AREA {home, foreign, etc}" while the "zone" and "domain" are already well defined in H.323. My personal view is that we should FIRST try to solve H.323 mobility problems within the context of "zone" and "domain" as far as practicable. I would argue that zone and domain are good enough to serve this purpose for now. (Pl. also see AT&T's and Motorola's contributions.) [Jaakko:] As I already said, I did not intent to define the terms: home area and visited area. I was just trying to illustrate the point I was making about not having the Home/visited zone terms defined yet. [Roy, Radhika R] It is good point. Let us define these. AT&T contributions have the detail definition for each term. 6. With respect to your comments that it appears that every GK will have HLF and VLF function, I would say that every GK will have the access to the HLF and VLF function. This capability for each GK has to be provided because of the fact that H.323 architecture is GK-centric. We do not have any choice because we are restricted by the H.323 architecture. [Jaakko:] I did not argue against this. The point is that if we identify a concept called the Home Zone, this already implies that each User has only one zone, in which he/she/it is not a "visiting user". I think this would be really restricting. [Roy, Radhika R] As I mentioned that H.323 is the GK-centric. A user may change his/her network point of point attachment, but it is still the same (Home) GK. So, a given (home) GK, there has to be another level of granularity to address mobility in terms of network point of attachment. Please see AT&T contribution how home and foreign network concept have solved the problem. Similar is the case with Motorola's contribution. The bottom line is that home/foreign GK concept does NOT imply any restriction to solve H.323 mobility. 6.1 With respect to your question whether HLF/VLF can be distributive or centralized, having said (in item 5) that every GK should have access to HLF and VLF function, it is up to implementation whether HLF and VLF function can be centralized or distributive. Please see AT&T contributions submitted in Red Bank how we can implement these functions in both distributive and centralized environment. [Jaakko:] This is actually quite much the point I was making. By defining the Home Zone we would in my mind actually be pointing to the centralized model. [Roy, Radhika R] By definition, there can as many GKs as one wish have in an H.323 system. So, by definition, the GK-centric H.323 architecture is distributive. By defining home/foreign GK, H.323 mobility also becomes distributive up to the point that a basic H.323 system allows us. So, we do not see any limitations. 6.2 In an analogy of this HLF/VLF function, I can bring another function - Directory services. For example, H.323 assumes that all the address (e.g., alias, transport, network) are kept by each GK. H.323 does not answer how the address information is maintained by each GK. People are using LDAP directory server. The question is: whether that directory service is distributive or centralized? I guess that it can be done in both ways depending on implementation. [Jaakko:] My point exactly. I would like that all GKs inside the same Administrative Domain would be able to access the same HLF/VLF functionality. [Roy, Radhika R] As I pointed out, this an implementation issue. I would argue that we should allow both options and let an implementor choose as it is necessary. Please also see AT&T contributions how both options can be addressed. 6.3 In AT&T contribution, it is shown that it better to make VLF distributive (per GK) although HLF function can be made both distributive and centralized. Again, this is a matter of implementation. As mentioned in AT&T contribution, we also need to define a kind of backend protocol for VLF and HLF (something like similar to Siemens, Nokia and Intel's contribution - TD-39: Security Services for Backend Services and Mobility in H.323). [Jaakko:] I would assume that you can distribute the HLF/VLF functionalities inside the Administrative Domain as you like, but distributing them between the Domains would be difficult. Actually I think that the concept of Administrative Domain was introduced in H.323 for this kind of reasons. [Roy, Radhika R] Again, H.323 system is GK-centric in a given domain. For inter-domain, it is BE-centric. In a given domain, H.323 architecture has to be GK-centric. Once we solve intra-zone and inter-zone (intra-domain) mobility, we can extend our experience for inter-domain problem as well. Please also see AT&T contribution how these problems have been addressed. My replies to 6.1 and 6.2 are also good for this case. 7. Again, I, personally, do not rule our to re-examine the benfit of "AREA" (e.g. location area [LA]) vs. "ZONE/DOMAIN" concept. May be it is in the second step. [Jaakko:] I am just a bit afraid that if we leave this kind of a major mobility related concept out of the first phase thinking process, we will find it much more difficult to include the concept in the second phase (where I think we will need it). Furthermore, I'm not convinced that the LA concept would not be useful in the pure H.323 approach either. [Roy, Radhika R] I think that it can be place holder for now. I would request to bring more detail contributions proposing solutions like AT&T and Motorola to prove the case better. Then, we can compare both solutions. In AT&T contribution, I feel that the LA can be accommodated to optimize the zone further. So, I do not see that it is a problem to accommodate the LA concept if needed. I personally prefer that we can better address this in the second phase once we solve the problem for the basic architecture. Hope that this email will clarify the things better. [Jaakko:] I think the main thing is that we got the discussion going on again. I'm kind of tired already, and I hope that I didn't mess things up too much in this mail. [Roy, Radhika R] Definitely, I also like that discussions must go on. We must be convinced that we have the best solution because it has the severe implications for all on-going mobility standard works throughout the world once we standardize H.323 mobility in SG16. Best regards, Radhika Same to you, Jaakko > -- > Edgar Martinez - Principal Staff Engineer > Email mailto:martinze@cig.mot.com > FAX 1-847-632-3145 - - Voice 1-847-632-5278 > 1501 West Shure Drive, Arlington Hgts. IL 60004 > Public: TIPHON & Other Stds - http://people.itu.int/~emartine/ > Private:TIPHON & Other Stds - http://www.cig.mot.com/~martinze/

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Re: H323mobility: Summary of discussion
by Roy, Radhika R, ALARC 05 Nov '99

05 Nov '99

Hi, Marc: You are right. Best regards, Radhika > -----Original Message----- > From: Roelands Marc [SMTP:Marc.Roelands@SIEMENS.ATEA.BE] > Sent: Friday, November 05, 1999 5:36 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: H323mobility: Summary of discussion > > Hi Jaakko, > > Just a small remark on your location area argumentation: > "what a LA is for: it is a grouping of NPoAs that are geographically > located > close to each other" assumes that NPoAs are restricted to a single > geographical point of attachment, which, as I understood it, was not the > definition we aggreed on. The NPoA in practice will be the IP address, > which cannot a priori be restricted to a single geographical area > (remember > the Mobile IP discussion...). > > Regards, > Marc > > -----Original Message----- > From: Jaakko Sundquist [mailto:jaakko.sundquist@NOKIA.COM] > Sent: Thursday, November 04, 1999 14:48 > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: H323mobility: Summary of discussion > > > Hi, Radhika et al, > > It seems that I did not make all my points so clear in my last message (as > I > said I was pretty tired when I wrote it). Also the discussion between me > and > Radhika (& Ed) seems to be getting out of hand. Thus I'll try to summarize > the points in the discussion and include my views in this message. > > As I see it, we have been discussing about three basic issues: > - The architectural placement of the HLF and VLF functionalities. The > discussion also has included (or actually it started from) the question > whether the terms: Home Zone and Visited Zone, with respective identifiers > should be defined or not. > - The two-step approach of first specifying the pure H.323 Mobility and as > a > second step the issues related to PLMN interworking. The discussion has > been > on whether (at least some of the) PLMN interworking issues should be > considered while working on the pure H.323 Mobility. > - The concept of the Location Area (LA). Whether we need that concept or > not > and if we need it, should it be considered already in the first step (see > the above point). > > I'll address all these points below. > > THE PLACEMENT OF HLF/VLF AND THE HOME/VISITED ZONE DISCUSSION > > I think we both/all agree on one thing: > The HLF and the VLF must be defined in the standard in such a way that it > is > possible for multiple GKs to access the same HLF/VLF. This allows for an > approach in which the HLF/VLF is distributed among many GKs while > simultaneously allowing the HLF/VLF to be associated with only a single > GK, > if this kind of a centralized design is desired. > > The thing that we disagree on is: I do NOT want to define the terms Home > Zone and Visited Zone (or similar) yet. I did not seem to make that clear > in > my last message. The reasons why I do not want to define this kind of > terms, > at least yet, are as follows. > > The term Home Zone leads in my mind to a definition in which every User is > associated with one and only one zone as the User's "Home". I.e. the HLF > containing the permanent information about the User can be accessed > through > the GK of the Home Zone and no other GK. Now, I do not think, Radhika, > that > this is what you intended, but if we talk about a Home Zone, this is the > kind of thing that first comes to my mind. > I currently have the idea that you meant that each User may have multiple > Home Zones, is that right, Radhika? If that is the case, I do not fully > understand why we would need the concept of the Home Zone at all (but > maybe > I'm just missing something). > The important thing in all these Home/Visited concepts is: how to identify > and access the HLF of a certain User and by accessing the HLF, update all > the relevant information in the HLF and in the VLFs. If there are multiple > Home Zones for a User, all the GKs of these zones can be used to access > the > HLF of the User, i.e. the HLF is identified by the Home Zone identifier > (if > this is not the case, what is the purpose of the Home Zone). Now, how is > it > determined, which GK should be Used in this case? The User must always > give > some "pointer" with which the HLF can be identified when the User enters a > zone (or LA, if we use them). In this case the Home Zone ID would be that > identifier. If always one of these Home Zones is given as the access point > to the HLF, this leads to a highly centralized model with this one single > zone and its GK as the central point. If, on the other hand, any of these > zones can be given, how is this zone picked, randomly? Furthermore, how > does > a GK of a User's Home Zone know that it is in fact a "Home GK" for that > User, if the User gives some other Home Zone ID than the one of the Home > Zone where he is located? > All the above reasons, in my opinion, lead to the fact that the HLF must > be > identified with an identifier that is NOT related to any single zone or > GK. > This is why I proposed the concept of Home Domain (I use the concept of an > Administrative Domain because, as Radhika mentioned, it is already defined > in H.323) in my contribution to the Red Bank meeting (APC-1659). In this > case the Home Domain would identify the HLF of a User and thus the GKs in > the Home Domain could identify that they are in fact a part of the Home > Domain and the HLF to which they have access, is the HLF of the User. If > the > User would be located in some other (Visited) Domain, his HLF could be > identified by the Home Domain (thus this model would be BE centric. > The Administrative Domain is, of course, not the only alternative to group > the zones, which form the "Home" of a User together, I just used it, > because > it is already defined. We could also define a HLF Identifier which is not > related to a Domain, but the GKs of the zones forming the User's "Home" > would recognize if the HLF to which they have access is the correct HLF > based on this identifier. > > THE TWO-STEP APPROACH DISCUSSION > > The two-step approach, as I understand it, means that we will first work > on > a pure end-to-end H.323 Mobility solution and after that has been done we > will define the interworking with legacy (and future) mobile networks. > Although I do agree that in general this is a good order to do these two > things, I would like to see some general interworking aspects taken into > consideration in the first phase. One example of these may be the Location > Area concept. I do not want to go into details of the interworking issues > in > the first step, but I'm afraid that if we do not think about the > interworking at all in the first step, we will end up defining some > functionalities in two different ways, one being the result of the first > step and the other an addition to this as the result of the second step > when > the solution of the first step is not capable of handling some general > interworking procedure, for example. > > I hope, I made my point clear despite the above text being somewhat > rambling... > > THE LOCATION AREA DISCUSSION > > This is actually an example of the problem I have with the "strict" > two-step > approach. Radhika is proposing that we try to solve the mobility in the > first step without the LA concept. I think it would be very beneficial, if > we at least consider it already in the first step. Furthermore, I am quite > sure we will need the concept in the second step, or else we will end up > with a very badly scalable system. > As I said in my earlier message, the LA concept will help to make the > H.323 > mobile systems more easily scalable, the price for this is, of course, the > increased complexity that the LAs bring to the system. To express shortly, > what a LA is for: it is a grouping of NPoAs that are geographically > located > close to each other. A zone also consists of NPoAs, but these NPoAs can > actually be geographically far from each other. In other words, a zone is > a > set of NPoAs that are grouped together for administrative purposes, not > because they are close to each other (which they need not be). When we are > dealing with wireless mobile terminals, this grouping based on the > geographical location becomes important and thus my opinion is that we > should consider the LA concept already in the first phase. > > - Jaakko Sundquist > ------------------------------------------------------- > In a hole in the ground there lived a hobbit. > Not a nasty, dirty, wet hole, filled with the ends of > worms and an oozy smell, nor yet a dry, bare, > sandy hole with nothing in it to sit down on or to eat: > it was a hobbit-hole, and that means comfort. > -------------------------------------------------------

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Re: H323mobility: Summary of discussion
by sgkim 05 Nov '99

05 Nov '99

안녕하세요. 김상길입니다. 수정할 내용은 없습니다. '구룹' -> '그룹'으로 변경하였습니다. 감사합니다. -----원본 메시지----- 보낸 사람: Roelands Marc <Marc.Roelands(a)SIEMENS.ATEA.BE> 받는 사람: ITU-SG16(a)mailbag.cps.intel.com <ITU-SG16(a)mailbag.cps.intel.com> 날짜: 1999년 11월 5일 금요일 오후 7:48 제목: Re: H323mobility: Summary of discussion >Hi Jaakko, > >Just a small remark on your location area argumentation: >"what a LA is for: it is a grouping of NPoAs that are geographically located >close to each other" assumes that NPoAs are restricted to a single >geographical point of attachment, which, as I understood it, was not the >definition we aggreed on. The NPoA in practice will be the IP address, >which cannot a priori be restricted to a single geographical area (remember >the Mobile IP discussion...). > >Regards, >Marc > >-----Original Message----- >From: Jaakko Sundquist [mailto:jaakko.sundquist@NOKIA.COM] >Sent: Thursday, November 04, 1999 14:48 >To: ITU-SG16(a)MAILBAG.INTEL.COM >Subject: H323mobility: Summary of discussion > > >Hi, Radhika et al, > >It seems that I did not make all my points so clear in my last message (as I >said I was pretty tired when I wrote it). Also the discussion between me and >Radhika (& Ed) seems to be getting out of hand. Thus I'll try to summarize >the points in the discussion and include my views in this message. > >As I see it, we have been discussing about three basic issues: >- The architectural placement of the HLF and VLF functionalities. The >discussion also has included (or actually it started from) the question >whether the terms: Home Zone and Visited Zone, with respective identifiers >should be defined or not. >- The two-step approach of first specifying the pure H.323 Mobility and as a >second step the issues related to PLMN interworking. The discussion has been >on whether (at least some of the) PLMN interworking issues should be >considered while working on the pure H.323 Mobility. >- The concept of the Location Area (LA). Whether we need that concept or not >and if we need it, should it be considered already in the first step (see >the above point). > >I'll address all these points below. > >THE PLACEMENT OF HLF/VLF AND THE HOME/VISITED ZONE DISCUSSION > >I think we both/all agree on one thing: >The HLF and the VLF must be defined in the standard in such a way that it is >possible for multiple GKs to access the same HLF/VLF. This allows for an >approach in which the HLF/VLF is distributed among many GKs while >simultaneously allowing the HLF/VLF to be associated with only a single GK, >if this kind of a centralized design is desired. > >The thing that we disagree on is: I do NOT want to define the terms Home >Zone and Visited Zone (or similar) yet. I did not seem to make that clear in >my last message. The reasons why I do not want to define this kind of terms, >at least yet, are as follows. > >The term Home Zone leads in my mind to a definition in which every User is >associated with one and only one zone as the User's "Home". I.e. the HLF >containing the permanent information about the User can be accessed through >the GK of the Home Zone and no other GK. Now, I do not think, Radhika, that >this is what you intended, but if we talk about a Home Zone, this is the >kind of thing that first comes to my mind. >I currently have the idea that you meant that each User may have multiple >Home Zones, is that right, Radhika? If that is the case, I do not fully >understand why we would need the concept of the Home Zone at all (but maybe >I'm just missing something). >The important thing in all these Home/Visited concepts is: how to identify >and access the HLF of a certain User and by accessing the HLF, update all >the relevant information in the HLF and in the VLFs. If there are multiple >Home Zones for a User, all the GKs of these zones can be used to access the >HLF of the User, i.e. the HLF is identified by the Home Zone identifier (if >this is not the case, what is the purpose of the Home Zone). Now, how is it >determined, which GK should be Used in this case? The User must always give >some "pointer" with which the HLF can be identified when the User enters a >zone (or LA, if we use them). In this case the Home Zone ID would be that >identifier. If always one of these Home Zones is given as the access point >to the HLF, this leads to a highly centralized model with this one single >zone and its GK as the central point. If, on the other hand, any of these >zones can be given, how is this zone picked, randomly? Furthermore, how does >a GK of a User's Home Zone know that it is in fact a "Home GK" for that >User, if the User gives some other Home Zone ID than the one of the Home >Zone where he is located? >All the above reasons, in my opinion, lead to the fact that the HLF must be >identified with an identifier that is NOT related to any single zone or GK. >This is why I proposed the concept of Home Domain (I use the concept of an >Administrative Domain because, as Radhika mentioned, it is already defined >in H.323) in my contribution to the Red Bank meeting (APC-1659). In this >case the Home Domain would identify the HLF of a User and thus the GKs in >the Home Domain could identify that they are in fact a part of the Home >Domain and the HLF to which they have access, is the HLF of the User. If the >User would be located in some other (Visited) Domain, his HLF could be >identified by the Home Domain (thus this model would be BE centric. >The Administrative Domain is, of course, not the only alternative to group >the zones, which form the "Home" of a User together, I just used it, because >it is already defined. We could also define a HLF Identifier which is not >related to a Domain, but the GKs of the zones forming the User's "Home" >would recognize if the HLF to which they have access is the correct HLF >based on this identifier. > >THE TWO-STEP APPROACH DISCUSSION > >The two-step approach, as I understand it, means that we will first work on >a pure end-to-end H.323 Mobility solution and after that has been done we >will define the interworking with legacy (and future) mobile networks. >Although I do agree that in general this is a good order to do these two >things, I would like to see some general interworking aspects taken into >consideration in the first phase. One example of these may be the Location >Area concept. I do not want to go into details of the interworking issues in >the first step, but I'm afraid that if we do not think about the >interworking at all in the first step, we will end up defining some >functionalities in two different ways, one being the result of the first >step and the other an addition to this as the result of the second step when >the solution of the first step is not capable of handling some general >interworking procedure, for example. > >I hope, I made my point clear despite the above text being somewhat >rambling... > >THE LOCATION AREA DISCUSSION > >This is actually an example of the problem I have with the "strict" two-step >approach. Radhika is proposing that we try to solve the mobility in the >first step without the LA concept. I think it would be very beneficial, if >we at least consider it already in the first step. Furthermore, I am quite >sure we will need the concept in the second step, or else we will end up >with a very badly scalable system. >As I said in my earlier message, the LA concept will help to make the H.323 >mobile systems more easily scalable, the price for this is, of course, the >increased complexity that the LAs bring to the system. To express shortly, >what a LA is for: it is a grouping of NPoAs that are geographically located >close to each other. A zone also consists of NPoAs, but these NPoAs can >actually be geographically far from each other. In other words, a zone is a >set of NPoAs that are grouped together for administrative purposes, not >because they are close to each other (which they need not be). When we are >dealing with wireless mobile terminals, this grouping based on the >geographical location becomes important and thus my opinion is that we >should consider the LA concept already in the first phase. > >- Jaakko Sundquist >------------------------------------------------------- > In a hole in the ground there lived a hobbit. > Not a nasty, dirty, wet hole, filled with the ends of > worms and an oozy smell, nor yet a dry, bare, >sandy hole with nothing in it to sit down on or to eat: > it was a hobbit-hole, and that means comfort. >------------------------------------------------------- >

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Re: H323mobility: Summary of discussion
by Roelands Marc 05 Nov '99

05 Nov '99

Hi Jaakko, Just a small remark on your location area argumentation: "what a LA is for: it is a grouping of NPoAs that are geographically located close to each other" assumes that NPoAs are restricted to a single geographical point of attachment, which, as I understood it, was not the definition we aggreed on. The NPoA in practice will be the IP address, which cannot a priori be restricted to a single geographical area (remember the Mobile IP discussion...). Regards, Marc -----Original Message----- From: Jaakko Sundquist [mailto:jaakko.sundquist@NOKIA.COM] Sent: Thursday, November 04, 1999 14:48 To: ITU-SG16(a)MAILBAG.INTEL.COM Subject: H323mobility: Summary of discussion Hi, Radhika et al, It seems that I did not make all my points so clear in my last message (as I said I was pretty tired when I wrote it). Also the discussion between me and Radhika (& Ed) seems to be getting out of hand. Thus I'll try to summarize the points in the discussion and include my views in this message. As I see it, we have been discussing about three basic issues: - The architectural placement of the HLF and VLF functionalities. The discussion also has included (or actually it started from) the question whether the terms: Home Zone and Visited Zone, with respective identifiers should be defined or not. - The two-step approach of first specifying the pure H.323 Mobility and as a second step the issues related to PLMN interworking. The discussion has been on whether (at least some of the) PLMN interworking issues should be considered while working on the pure H.323 Mobility. - The concept of the Location Area (LA). Whether we need that concept or not and if we need it, should it be considered already in the first step (see the above point). I'll address all these points below. THE PLACEMENT OF HLF/VLF AND THE HOME/VISITED ZONE DISCUSSION I think we both/all agree on one thing: The HLF and the VLF must be defined in the standard in such a way that it is possible for multiple GKs to access the same HLF/VLF. This allows for an approach in which the HLF/VLF is distributed among many GKs while simultaneously allowing the HLF/VLF to be associated with only a single GK, if this kind of a centralized design is desired. The thing that we disagree on is: I do NOT want to define the terms Home Zone and Visited Zone (or similar) yet. I did not seem to make that clear in my last message. The reasons why I do not want to define this kind of terms, at least yet, are as follows. The term Home Zone leads in my mind to a definition in which every User is associated with one and only one zone as the User's "Home". I.e. the HLF containing the permanent information about the User can be accessed through the GK of the Home Zone and no other GK. Now, I do not think, Radhika, that this is what you intended, but if we talk about a Home Zone, this is the kind of thing that first comes to my mind. I currently have the idea that you meant that each User may have multiple Home Zones, is that right, Radhika? If that is the case, I do not fully understand why we would need the concept of the Home Zone at all (but maybe I'm just missing something). The important thing in all these Home/Visited concepts is: how to identify and access the HLF of a certain User and by accessing the HLF, update all the relevant information in the HLF and in the VLFs. If there are multiple Home Zones for a User, all the GKs of these zones can be used to access the HLF of the User, i.e. the HLF is identified by the Home Zone identifier (if this is not the case, what is the purpose of the Home Zone). Now, how is it determined, which GK should be Used in this case? The User must always give some "pointer" with which the HLF can be identified when the User enters a zone (or LA, if we use them). In this case the Home Zone ID would be that identifier. If always one of these Home Zones is given as the access point to the HLF, this leads to a highly centralized model with this one single zone and its GK as the central point. If, on the other hand, any of these zones can be given, how is this zone picked, randomly? Furthermore, how does a GK of a User's Home Zone know that it is in fact a "Home GK" for that User, if the User gives some other Home Zone ID than the one of the Home Zone where he is located? All the above reasons, in my opinion, lead to the fact that the HLF must be identified with an identifier that is NOT related to any single zone or GK. This is why I proposed the concept of Home Domain (I use the concept of an Administrative Domain because, as Radhika mentioned, it is already defined in H.323) in my contribution to the Red Bank meeting (APC-1659). In this case the Home Domain would identify the HLF of a User and thus the GKs in the Home Domain could identify that they are in fact a part of the Home Domain and the HLF to which they have access, is the HLF of the User. If the User would be located in some other (Visited) Domain, his HLF could be identified by the Home Domain (thus this model would be BE centric. The Administrative Domain is, of course, not the only alternative to group the zones, which form the "Home" of a User together, I just used it, because it is already defined. We could also define a HLF Identifier which is not related to a Domain, but the GKs of the zones forming the User's "Home" would recognize if the HLF to which they have access is the correct HLF based on this identifier. THE TWO-STEP APPROACH DISCUSSION The two-step approach, as I understand it, means that we will first work on a pure end-to-end H.323 Mobility solution and after that has been done we will define the interworking with legacy (and future) mobile networks. Although I do agree that in general this is a good order to do these two things, I would like to see some general interworking aspects taken into consideration in the first phase. One example of these may be the Location Area concept. I do not want to go into details of the interworking issues in the first step, but I'm afraid that if we do not think about the interworking at all in the first step, we will end up defining some functionalities in two different ways, one being the result of the first step and the other an addition to this as the result of the second step when the solution of the first step is not capable of handling some general interworking procedure, for example. I hope, I made my point clear despite the above text being somewhat rambling... THE LOCATION AREA DISCUSSION This is actually an example of the problem I have with the "strict" two-step approach. Radhika is proposing that we try to solve the mobility in the first step without the LA concept. I think it would be very beneficial, if we at least consider it already in the first step. Furthermore, I am quite sure we will need the concept in the second step, or else we will end up with a very badly scalable system. As I said in my earlier message, the LA concept will help to make the H.323 mobile systems more easily scalable, the price for this is, of course, the increased complexity that the LAs bring to the system. To express shortly, what a LA is for: it is a grouping of NPoAs that are geographically located close to each other. A zone also consists of NPoAs, but these NPoAs can actually be geographically far from each other. In other words, a zone is a set of NPoAs that are grouped together for administrative purposes, not because they are close to each other (which they need not be). When we are dealing with wireless mobile terminals, this grouping based on the geographical location becomes important and thus my opinion is that we should consider the LA concept already in the first phase. - Jaakko Sundquist ------------------------------------------------------- In a hole in the ground there lived a hobbit. Not a nasty, dirty, wet hole, filled with the ends of worms and an oozy smell, nor yet a dry, bare, sandy hole with nothing in it to sit down on or to eat: it was a hobbit-hole, and that means comfort. -------------------------------------------------------

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[Robustness] Call Clearing related
by Orit Levin 05 Nov '99

05 Nov '99

Hello all! I completely agree that after multiplexing of H.323 calls is possible over the same TCP connection, we have to speak (and upgrade the H.323 specification) explicitly using separate terms: Q.931 logical Connection, H.245 logical Connection and the their TCP channel(s) below. Any better names are welcomed. I would vote for H.323v4 to strike out the old text and rewrite the rules using "new" explicit terminology. I understand that part of this rules are going to be based on the new Robustness work. This is why this Robustness work is so urgent and part of it should be done for H.323v4 i.e. for Feb. 00. So... as a part of this Robustness work and using this new terminology, I would like to start from cleaning up "relatively" simple issues. According to current state of the standard, it is not explicitly mandated to clean H.323 Call if its Q.931 TCP connection is reported to be lost from any reason. There are two reasons being claimed against complete closure of the Call in this situation: (a) May be the other side (or the GK) intentionally closed the Q.931 logical Connection and its corresponding TCP channel in order to free up its internal resources, but still wants the H.245 logical Connection and the Call to stay in place. (b) May be it is a real TCP connection failure, but future Robustness Specification will define a way to recover from TCP connection failure without dropping the Call. As a result, in practice upon TCP connection failure (which may be a part of other side failure) H.323 calls are being hanging up without local resources freeing so essential for H.323 users (and networks)!!! I think that considering (a) and (b) as a general case is a mistake. I will try to explain myself below: (a) If we look in Implementers Guide V.1 (see the attachment) text (which has been lost on its way to V.2), the problem was identified long ago. It was recommended to keep the Q.931 logical Connection open. My question is: Do we know about any commercial H.323v1-v3 implementations that intentionally close Q.931 TCP channel but still expect the Call to be maintained? I suggest to find the practical answer and then debate how to keep these implementations happy. (b) If the case is a real TCP connection failure, the future possible way to recover is adding application (i.e. H.323) layer means (i.e. messages/parameters) and procedures to open an alternate TCP connection between the parties and associate it to the previous Q.931 logical connection. Therefore if one of the parties is of H.323v1-3, there is no way in the future to find a remedy for such a Call. The bottom line: If one of the parties in H.323 call doesn't support RobustnessV.1 and Q.931 TCP connection failure has been reported from TCP layer, the call shall be cleared and resources freed. Any comments? Orit Levin RADVision Inc. 575 Corporate Drive Suite 420 Mahwah, NJ 07430 Tel: 1 201 529 4300 (230) Fax: 1 201 529 3516 www.radvision.com orit(a)radvision.com -----Original Message----- From: Paul E. Jones <paul.jones(a)TIES.ITU.INT> To: ITU-SG16(a)MAILBAG.INTEL.COM <ITU-SG16(a)MAILBAG.INTEL.COM> Date: Tuesday, November 02, 1999 11:44 PM Subject: Re: [Robustness] Re: Call Clearing related >Chris, > >> A technical question on the second paragraph of your mail: how do >endpoints >> KNOW that they're connected directly rather than through a gatekeeper, in >order >> to decide whether they can (under the current system) drop the >call-signalling >> channel? > >First of all... sorry for the delayed response. I am a bit behind :-) > >I, too, noticed this funny little sentence in the standard. In theory, the >GK would signal that the call is being routed, but that may not necessarily >be the case. > >I believe it is clear that we must address this issue. I would like to >strike the text as I proposed. I also believe it might be wise to add a >paragraph to V4 noting that V3 and older terminals may close the call >signaling channel, along the lines of your e-mail. > >Another issue we have at hand is that of "what is a call signaling channel?" >There used to be a one to one mapping between TCP connections and call >signaling channels. This is not the case any longer-- one may have multiple >calls over the same call signaling channel and one may not even use TCP. > >Making this distinction will be important for the robustness work being >started, as the "logical" connection (the call signaling channel) and the >"physical" connection (the TCP or UDP connection) must be referred to >independently. (I'm quite open to new terms for here...). It is important >to recognize whether an endpoint has closed the call signaling channel (as >we understand it today) or if the physical connection has failed. Since we >do not signal that we are going to close the call signaling channel today-- >we just close the socket-- it makes this problem more difficult. > >Paul

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unsubscribe
by Cheng-Yao Ni 04 Nov '99

04 Nov '99

cynie(a)dcs.ccl.itri.org.tw -------------------------------------------- Sam Ni Senior Member of Technical Staff TIBCO Software Inc. Taiwan 16F-2, No. 295 Sec. 2 Kuang Fu Rd., Hsinchu, Taiwan, R.O.C. Tel: +886-3-5728842 ext. 210 Fax: +886-3-5714059 GSM: +886-930817613

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