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

Re: Firewalls [was: H.320 gateways a MEGACO / ITU]
by Iain Barker 06 Apr '99

06 Apr '99

One solution would be not to expect the firewall to 'find' which ports to open, but instead for the gateway to inform the firewall of the nature of the underlying connection. FYI, SIEMENS have a submission to TIPHON which disusses how a media gateway [H.323 in their example] can instruct the firewall which IP ports to allow through. http://docbox.etsi.org/tech-org/TIPHON/Document/TIPHON/05-9903-Philadelphia/ 12TD054.rtf -- Iain Barker International data, Nortel PND, Maidenhead SL64AG UK Note: The above posting may not represent the views of Nortel. -----Original Message----- From: Douglas Clowes [mailto:dclowes@OZEMAIL.COM.AU] Sent: 01 April 1999 02:14 To: ITU-SG16(a)MAILBAG.INTEL.COM Subject: Re: Firewalls [was: H.320 gateways a MEGACO / ITU] [deletia] Assuming that the SA between H1 and H2 involves payload encryption, such as ESP, and is call signalling or H.245, how does SG2 cope with finding the IP/port pairs, even in a text based protocol? My interest extends beyond megaco/H.gcp, and includes Annex G. How do we handle this in the more general case? Douglas

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Re: Issues Around Support of Multimedia
by Ami Amir 06 Apr '99

06 Apr '99

Hi Fernando, I think we should address at least one issue in detail: Support of multiple media streams (I am assuming that each media stream is a context) which are part of a single "Point to Point Call" (for lack of a better term) that are egressing through a MG into a single PSTN connection. This is relevant for gateways between PSTN and IP or for gateways between native ATM and IP. Relevant issues there: 1. Define that a context supports only one media stream (RTP) - equivalent to an H.245 logical channel. 2. Decide that when there is a need for an association between contexts that on the PSTN side are "joined", to use the RTP mechanisms (see Scott Petrack's comments). This will allow a "smart" MGC to do all the rest. Most of the other issues raised seem to me like re-inventions of wheels. If we try to enlarge the scope to make MEGACO a generic call control protocol for everything - we will end up re-writing H.323. Ami -----Original Message----- From: Fernando Cuervo [SMTP:cuervo@NORTELNETWORKS.COM] Sent: Tuesday, April 06, 1999 5:00 AM To: ITU-SG16(a)mailbag.cps.intel.com Subject: Re: Issues Around Support of Multimedia Tom, What are we supposed to do from the point of view of the charter? Would it suffice to have a warm-fuzzy feeling that the protocol is extensible (this could be possible by having one or more "reasonable" proposals to handle Context "behaviour" and sychronisation between contexts but not necessarily reaching an agreement on the "best" way to do it) Fernando > ---------- > From: Taylor, Tom-PT [CAR:5V00-I:EXCH] > Sent: April 5, 1999 12:09 PM > To: megaco(a)BayNetworks.COM; itu-sg16(a)mailbag.cps.intel.com > Subject: Issues Around Support of Multimedia > > I have suggested some directions for exploration of solutions to the > problem > of support of multimedia over the past week, but I suspect such > suggestions > go beyond my role as WG Chair. Hence I am taking a step backward and > simply > summarizing the issues for others to resolve. > > Issue 1: representation of connection topologies for multiple media types. > > It seems to me that contexts are not topologies themselves, but rather > represent envelopes within which different topologies will be realized > depending on the mode settings for the associated terminations. > > Requirements: > a) Coordinate between different media streams (e.g. for lip-synch, > stereo). > b) Represent degenerate cases simply (e.g. audio-only connections, > two-point connections). > c) Support multicast. > > Issue 2: support for different multipoint, medium-specific bridging > methods. > > For audio, the most obvious bridging method sums all inputs except that of > the party to which the signal is being sent. For video, one can have > continuous presence, most recent speaker, and probably lots of others. > > Issue 3: support for Chair-controlled conferences. > > We most assuredly do not want to develop yet another conference control > protocol. Nevertheless, we must understand conference control and how it > could affect the messaging between the MG and MGC. > > Issue 4: support for T.120 multipoint data conferencing service. > > T.120 assigns roles to individual nodes within a conference network. Can > the MG infer its role from the context cardinality (two-point vs. > multipoint), or is additional information required? > > Meta-issue: where do Megaco's interests stop and those of SG 16 take over? > Are we reaching the stage where some things have to be marked "for further > study", or do we work through all the issues now to make sure our base > solution will cover all needs? > > > Tom Taylor > E-mail: taylor(a)nortelnetworks.com (internally Tom-PT Taylor) > Tel.: +1 613 765 4167 (internally 395-4167) > This is frequently forwarded to my residence. >

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Re: Issues Around Support of Multimedia
by Fernando Cuervo 05 Apr '99

05 Apr '99

Tom, What are we supposed to do from the point of view of the charter? Would it suffice to have a warm-fuzzy feeling that the protocol is extensible (this could be possible by having one or more "reasonable" proposals to handle Context "behaviour" and sychronisation between contexts but not necessarily reaching an agreement on the "best" way to do it) Fernando > ---------- > From: Taylor, Tom-PT [CAR:5V00-I:EXCH] > Sent: April 5, 1999 12:09 PM > To: megaco(a)BayNetworks.COM; itu-sg16(a)mailbag.cps.intel.com > Subject: Issues Around Support of Multimedia > > I have suggested some directions for exploration of solutions to the > problem > of support of multimedia over the past week, but I suspect such > suggestions > go beyond my role as WG Chair. Hence I am taking a step backward and > simply > summarizing the issues for others to resolve. > > Issue 1: representation of connection topologies for multiple media types. > > It seems to me that contexts are not topologies themselves, but rather > represent envelopes within which different topologies will be realized > depending on the mode settings for the associated terminations. > > Requirements: > a) Coordinate between different media streams (e.g. for lip-synch, > stereo). > b) Represent degenerate cases simply (e.g. audio-only connections, > two-point connections). > c) Support multicast. > > Issue 2: support for different multipoint, medium-specific bridging > methods. > > For audio, the most obvious bridging method sums all inputs except that of > the party to which the signal is being sent. For video, one can have > continuous presence, most recent speaker, and probably lots of others. > > Issue 3: support for Chair-controlled conferences. > > We most assuredly do not want to develop yet another conference control > protocol. Nevertheless, we must understand conference control and how it > could affect the messaging between the MG and MGC. > > Issue 4: support for T.120 multipoint data conferencing service. > > T.120 assigns roles to individual nodes within a conference network. Can > the MG infer its role from the context cardinality (two-point vs. > multipoint), or is additional information required? > > Meta-issue: where do Megaco's interests stop and those of SG 16 take over? > Are we reaching the stage where some things have to be marked "for further > study", or do we work through all the issues now to make sure our base > solution will cover all needs? > > > Tom Taylor > E-mail: taylor(a)nortelnetworks.com (internally Tom-PT Taylor) > Tel.: +1 613 765 4167 (internally 395-4167) > This is frequently forwarded to my residence. >

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Issues Around Support of Multimedia
by Tom-PT Taylor 05 Apr '99

05 Apr '99

I have suggested some directions for exploration of solutions to the problem of support of multimedia over the past week, but I suspect such suggestions go beyond my role as WG Chair. Hence I am taking a step backward and simply summarizing the issues for others to resolve. Issue 1: representation of connection topologies for multiple media types. It seems to me that contexts are not topologies themselves, but rather represent envelopes within which different topologies will be realized depending on the mode settings for the associated terminations. Requirements: a) Coordinate between different media streams (e.g. for lip-synch, stereo). b) Represent degenerate cases simply (e.g. audio-only connections, two-point connections). c) Support multicast. Issue 2: support for different multipoint, medium-specific bridging methods. For audio, the most obvious bridging method sums all inputs except that of the party to which the signal is being sent. For video, one can have continuous presence, most recent speaker, and probably lots of others. Issue 3: support for Chair-controlled conferences. We most assuredly do not want to develop yet another conference control protocol. Nevertheless, we must understand conference control and how it could affect the messaging between the MG and MGC. Issue 4: support for T.120 multipoint data conferencing service. T.120 assigns roles to individual nodes within a conference network. Can the MG infer its role from the context cardinality (two-point vs. multipoint), or is additional information required? Meta-issue: where do Megaco's interests stop and those of SG 16 take over? Are we reaching the stage where some things have to be marked "for further study", or do we work through all the issues now to make sure our base solution will cover all needs? Tom Taylor E-mail: taylor(a)nortelnetworks.com (internally Tom-PT Taylor) Tel.: +1 613 765 4167 (internally 395-4167) This is frequently forwarded to my residence.

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ASN.1 vs Text
by Tom-PT Taylor 01 Apr '99

01 Apr '99

Since the other responses seem to have gone off into a discussion of firewalls, let me respond to this more directly by recalling a bit of past discussion. 1) On the Megaco list, we finally agreed that the text vs. binary question is something to be resolved by experiment. 2) In Turin (I think), the general opinion was that the protocol would have to be binary to achieve the required performance. Interestingly enough, however, no one that I recall felt that it should be PER ASN.1 (or even, I think, BER ASN.1). Good reasons were given at the time. It would be good if someone can remember them, but I think it has something to do with processing performance and less risk of fragmentation than call signalling. 3) We have had an occasionally recurring suggestion on the Megaco list that the Media Gateway control protocol should conform to the format of other messaging out of the MGC, for the reason you give (i.e. to minimize transcoding). Interestingly, the person advocating this was talking about billing data, not signalling. The counter-argument on the list is that the Media Gateway control protocol must work with different signalling protocols (for example in H.GCP's case, with any of the H-series systems), so there is no point in optimizing it for just one. The real sticking point of debate is going to be whether the media description structures will be those defined for H.245 OLC etc., or SDP. Text vs. binary is a closely related but broader debate. I'd suggest we start thinking about experimental design. > -----Original Message----- > From: Ami Amir [SMTP:amir@RADVISION.RAD.CO.IL] > Sent: Wednesday, March 31, 1999 4:15 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: H.320 gateways a MEGACO / ITU > > Hi > > During the last MEGACO conference call - Tom Taylor asked what could > hinder > ITU acceptance of the MEGACO work. It is obviously to everybody's interest > that IETF and ITU standards merge. As an example - it would be great if > the > MEGACO work could become an ITU SG 16 contribution. > > An obvious item is efficient multimedia support (as reflected also in > John's > mail). > > However, I think that one of the even more major difficulties facing us > will > be the encoding scheme (ASN.1 vs Text). > > There are many who feel that ASN.1 is too heavy and complex for simple > devices, and should be avoided. This was one of the major reasons for the > emergence of SIP. > > On the other hand, experience in the ITU H.323 work has shown that since > ASN.1 is the encoding scheme on the PSTN side, the use of ASN cleared the > way for PSTN to IP interoperability. This feature will be extremely > important in hybrid networks that need to provide Intelligent Network (IN) > services (e.g. "800"), while retaining the investment in existing IN, > billing and directory services (411). > > Another problem is that if ASN.1 is not chosen, every device that will > have > to connect between a MEGACO component and H.323 will need to dis-assemble > and re-assemble (transcode) messages, and hence network performance will > suffer, and those devices will be more complex. A prime example - MGC to > GK > communications. > > I am not promoting a specific approach. I just think that this complex > issue > needs to be addressed if we want to be able to be able accept a universal > protocol. > > Do you think this is really a problem? > If so - any ideas on how to bridge the gap? > > Ami > > -----Original Message----- > From: John Segers [SMTP:jsegers@lucent.com] > Sent: Tuesday, March 30, 1999 6:27 PM > To: ITU-SG16(a)mailbag.cps.intel.com > Subject: H.320 gateways > > People, > > In yesterday's conference call, the subject of H.320 GWs was > raised > briefly. In my opinion, the connection model and protocol should > be > able > to deal with H.320. I would like to continue discussion on it on > the > mailing list. > > H.320 allows a user to have a session with both audio and video on > a > single 64 kbit/s channel such as an ISDN B-channel. The same > channel > carries some signalling information (frame alignment, bitrate > allocation). To a MG supporting H.320, this means that on a > single > endpoint, three streams can come in, carrying different types of > media. > The current connection model of megaco/H.gcp does not cater to > this. > I > see two possible solutions: > > The first is to allow multiple media in one context and to > describe > for > terminations the logical streams they carry. In a picture: > > +----------+ > | | > | +--------- signalling (FAS, BAS) > | | > B-channel ==========+ +--------- audio (16 kbit/s) > | | > | +--------- video (46.4 kbit/s) > | | > +----------+ > > The second solution is to have separate terminations for the > different > streams. They would all "connect to" the same physical endpoint. > In > order to properly identify the terminations, it is necessary to > have > logical names for them. The physical endpoint they connect may > have > the > hierarchical name proposed in the megaco document. > > Another example of a H.320 session is the case of two B-channels > being > used for an audiovisual call. The following frame structure is > then > possible. > > +--------------------------++-----------------------+ > | Channel 1 || Channel 2 | > +-----+--+--+--+--+--+--+--++--+--+--+--+--+--+--+--+ > |Bit 1|B2|B3|B4|B5|B6|B7|B8||B1|B2|B3|B4|B5|B6|B7|B8| > +-----+--+--+--+--+--+--+--++--+--+--+--+--+--+--+--+ > 1 | a1 |a2|a3|a4|a5|a6|v1|F ||v2|v3|v4|v5|v6|v7|v8|F | > 2 | a7 |a8|a9|a |a |a |v9|F ||v |v |v |v |v |v |v |F | > 3 | a |a |a |a |a |a |v |F ||v |v |v |v |v |v |v |F | > 4 | a | | | | |a |v |F ||v | |v |F | > 5 | a | | | | |a |v |F ||v | |v |F | > 6 | a | | | | |a |v |F ||v | |v |F | > 7 | a | | | | |a |v |F ||v | |v |F | > 8 | a | | | | |a |v |F ||v | |v |F | > +---------------------------------------------------+ > 9 | a | | | | |a |v |B ||v | |v |B | > 10 | a | | | | |a |v |B ||v | |v |B | > 11 | a | | | | |a |v |B ||v | |v |B | > 12 | a | | | | |a |v |B ||v | |v |B | > 13 | a | | | | |a |v |B ||v | |v |B | > 14 | a | | | | |a |v |B ||v | |v |B | > 15 | a | | | | |a |v |B ||v | |v |B | > 16 | a | | | | |a |v |B ||v | |v |B | > +---------------------------------------------------+ > 17 | a | | | | |a |v |v ||v | |v |v | > . > . > . > 80 | a | | | | |a |v |v ||v | |v |v | > +---------------------------------------------------+ > > (a=audio, v=video, F=FAS, B=BAS). > > We see that the video stream is split up over two channels. In > order to > cater to this, it seems we have to allow terminations to receive > media > from and send it to multiple physical endpoints. The two > approaches > outlined above can both be extended to allow this. Both extensions > will > lead to the introduction of logical names for terminations. In > the > first approach there will be one termination "containing" two > B-channels > on one side and three logical streams on the other. In the second > approach there will be three terminations, the one for the video > stream > referencing both B-channels, the ones for signalling and audio > referencing only channel 1. > > The second approach allows us to keep separate contexts for > different > media types. It is then easy to delete, for instance, the video > part of > a session (session used loosely to desribe the contexts for the > audio > and video). > > The first approach groups the streams coming from/going to one > user, > making it possible to remove a user from a context more easily. > > > Personally, I can't decide which approach I would prefer. How do > others > feel about these ideas? > > Regards, > > John Segers > -- > John Segers email: > jsegers(a)lucent.com > Lucent Technologies Room HE > 344 > Dept. Forward Looking Work phone: +31 35 687 > 4724 > P.O. Box 18, 1270 AA Huizen fax: +31 35 687 > 5954

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TINA '99 in Hawaii mid April , last call for participation
by Martine.Lapierre＠ALCATEL.FR 01 Apr '99

01 Apr '99

Dear colleague, In this message is the text for the final call for participation for TINA'99. It is also accessible at http://www.tinac.com/tina99.html. I apologize if you received the TINA'99 information before, this is just a check that you were informed before the last chance for registration has arrived. The scientific committee expressed a gratitude for the excellence of the papers submitted, especially on VoIP and IN for IP. May I insist on the quality of the Panel of Wednesday afternoon where very senior people will express their views on the future of telecommunication networks: H. Aldermeshian AT&T T. Aoki NTT J. Craveur France Telecom E. Raubold Deutsche Telekom T. Rowbotham British Telecom If you are interested in attending, and desire to do so, I urge you to follow the instructions in the call. I look forward to seeing you in Hawaii. Martine Lapierre <martine.lapierre(a)alcatel.fr> TINA'99 Telecommunications Information Networking Architecture Conference 1999 Turtle Bay Resort, Oahu, Hawaii, USA - 12-15 April 1999 The Application of Distributed Computing Technologies to Telecommunications Solutions The Telecommunication Information Networking Architecture (TINA) Consortium invites you to attend the TINA'99 Conference on applications of state-of-the-art distributed computing technologies to problems of the globally converging telecommunications and computing domains. TINA'99 is an open international conference, with participation from researchers and developers in open networking technologies related to telecommunication and information systems. HOSTED BY: Hewlett-Packard Laboratories IN COOPERATION WITH: * IEEE Communications Society * Object Management Group SUPPORTED BY: * Hewlett-Packard Company * TINA Consortium CONFERENCE STRUCTURE AND PARTICIPATION TINA'99 consists of tutorials, keynote addresses, technical sessions, and demonstrations. The tutorials are on 12 April, with the keynote addresses and technical sessions occupying a single track on 13 April, and two tracks on 14 April and until noon on 15 April. A preliminary program is available for your perusal. (http://www.tinac.com/99/Conference/program.pdf) REGISTRATION To attend the conference, you must register for the conference and book accommodations with the conference hotel. The relevant forms are: * Registration Form (http://www.tinac.com/99/Conference/regform.html) * Hotel Information and Booking Form (http://www.tinac.com/99/Conference/regform.html) The registration includes admittance to the tutorials of your choice, the technical sessions, the reception, and the conference dinner. We also will accept American Express cards for the conference registration. There is still room for late registrants, and the hotel will continue to accept bookings at the preferred rate on a space available basis. If you are interested in attending, please register for the conference and book your accommodations as soon as possible! VENUE The Turtle Bay Hilton Resort is located on the north shore of the island of Oahu. Honolulu is located on the south shore of Oahu. A link to the resort's web site is available by following the Hotel Information and Booking Form link above. Transportation Airport to Turtle Bay - approximately 1 hour Hotel Shuttle - Reservations must be made by 3:30pm, Hawaii time, at least one day prior. Call Turtle Bay Hilton, Assistant Manager - 808/293-1286 x23. Credit card needed to confirm reservations. Shuttle Timetable Depart Honolulu 7:45am 8:45am 9:45am 10:45am 1:!5pm 4:45pm Intl. Arrive Turtle 8:45am 9:45am 10:45am 11:45am 2:15pm 5:45pm Bay Depart Turtle 9:00am 10:00am 11:00am 12:00pm 2:30pm 6:00pm Bay Arrive Honolulu 10:00am 11:00am 12:00pm 1:00pm 3:30pm 7:00pm Intl. Airport pickup outside Baggage Claim area of your Airline. Rates: Registered Guest per person $30.00 + 1.25 = $31.25 (USD) Non Guest per person $95.00 + 3.96 = $ 98.96 (USD) Child (1-5 years) registered $15.00 + .62 = $15.62 (USD) Child ( 1-5 years) non guest $47.50 + 1.98 = $ 49.48 (USD) Limo - Northshore Limousine - 808/293-1447 Cost - $114.11 - includes tax & tip (USD) Call ahead to make reservations Taxi Ride - Cost $85 - $115 (USD) ENQUIRIES If you require any other information, please contact us at +1-650-857-3377 or send e-mail to Renee_Coca(a)hpl.hp.com.

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Re: Firewalls [was: H.320 gateways a MEG
by Sengodan Senthil NRC/Boston 01 Apr '99

01 Apr '99

Douglas, IMHO, I think that the issue comes down to trust. The SAs need to be so constructed that the trust model is satisfied. In case 3, where SA2 is an ESP SA between EP1-EP2: Such a deployment may be chosen when EP1 does not trust SG1 and EP2 does not trust SG2 to look inside the packet. The SPD present at EP1 would reflect the policy that currently exists in firewalls. The firewall functionality has essentially been distributed to the edge (EP1) in this case. If the SG is trusted - which is the case with most firewalls - then, the scenario in case 3 should probably not be chosen. An ESP SA can exist between SG1 and SG2. If there is a problem of snooping within the AD, then an ESP SA can be established between EP1 - SG1 and SG2-EP2 as well. - Senthil ---------- From: Mailing list for parties associ To: ITU-SG16 Subject: Re: Firewalls [was: H.320 gateways a MEGACO / ITU] Date: Thursday, April 01, 1999 3:08PM At 19:03 1999-03-31 -0800, Matt Holdrege wrote: >If you are using ESP, there are no worries. The endpoints unwrap the >original packet and process it as normal. The firewall doesn't know or care >about the original internal packet. In Melinda's case, and I think it applies to the megaco messages as well, if that pdu contains protocol addresses, and the firewall wants/needs to unblock them (but not translate them), it certainly does care. I think we are talking about firewalls that filter/block all but a few configured ports, and open others when genuine needs are detected. >But if we are talking about MEGACO and I originally thought we were, you >don't need to use ESP if you don't want to. For security's sake, you may >wish to use AH in which case the firewall will simply authenticate the >packet and pass it through without any worries. Assume for the moment that the MG lives behind a firewall, and the MGC is "out there", communicating on the well known and open port allocated to megaco. An RTP session needs to be opened, on a dynamically allocated port that the firewall is blocking. The session is to be made from another dynamically allocated port, on a different MG, somewhere "out there". For security reasons, the megaco protocol exchanges between the MGC and MG are encrypted, according to a security association between themselves. The firewall is seeing encrypted pdu's that it cannot examine for addresses. How will media flow to these blocked ports? I think that the other questions were similar, but the messages were Q.931 setup, or H.245 OLC and the firewall problem was the PER coding. It's worse with ESP/TLS than with PER, but it's still the same-ish problem. Using AH does not provide privacy. An eavesdropper can snoop dial strings, which can be sensitive. An eavesdropper can spot IP/port pairs, which it knows are going to be opened by the firewall, for targeting denial of service attacks. It would not be impossible to find ESP being used on megaco. >The only worries are if you are using NAT. And yes, the problem also arises with NAT, where the firewall also wants to _change_ the pdu. See: http://www.ietf.org/internet-drafts/draft-ietf-nat-protocol-complications-00 .txt :-) > >At 11:14 AM 4/1/99 +1000, Douglas Clowes wrote: >>Hi Matt, >> >>I've read 2401 (IPsec), 2402 (AH), and 2406 (ESP) before. I've also >>skimmed, but probably not understood, the ones on IKE and ISAKMP and OAKLEY >>too. I've just re-skimmed 2401/2/6 and still don't have the answer. >> >>Re-reading the postings, they're about H.323 proxies, call signalling, and >>H.245 - some people are talking about H.323 rather than megaco/H.gcp, and >>that's part of the problem: different threads by different people. >> >>My points are several, and relate to firewalls (as noted by the subject >>change). >> >>In a mode 3 security association: >>> 3. neither endpoint is the same -- The inner and outer >>> tunnels could each be either AH or ESP. >>> >>> Host 1 --- Security ---- Internet -- Security --- Host 2 >>> | Gwy 1 Gwy 2 | >>> | | | | >>> | --Security Assoc 1 (tunnel)- | >>> | | >>> -----------Security Association 2 (tunnel)----------- >> >>where Security Association 2 is ESP, how is SG1 or SG2 going to do packet >>filtering and port opening? >> >>Or, if SG1/SG2 is a single entity, as in Case 4: >>> ====================================================== >>> | | >>> |============================== | >>> || | | >>> || ---|----------------------|--- >>> || | | | | >>> H1* ----- (Internet) ------| SG2* ---- (Local ----- H2* | >>> ^ | Intranet) | >>> | ------------------------------ >>> could be dialup admin. boundary (optional) >>> to PPP/ARA server >> >>or SG2, here, is "just" a firewall, instead of a Signalling Gateway. >> >>Assuming that the SA between H1 and H2 involves payload encryption, such as >>ESP, and is call signalling or H.245, how does SG2 cope with finding the >>IP/port pairs, even in a text based protocol? >> >>My interest extends beyond megaco/H.gcp, and includes Annex G. How do we >>handle this in the more general case? >> >>Douglas >> >>At 16:05 1999-03-31 -0800, Matt Holdrege wrote: >>>You can read RFC 2401 & 2402 to find out about IPsec and AH. And this >>>discussion is about MEGACO/H.GCP which is not the same as H.323. >> >> >> > >

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Re: H.320 gateways a MEGACO / ITU
by Ami Amir 01 Apr '99

01 Apr '99

Melinda By transcoding I meant that specific information fields which contain identical information but are encoded differently need to be translated from one format to another. Ami -----Original Message----- From: Melinda Shore [SMTP:shore@ITHACA-VIENNASYS.COM] Sent: Wednesday, March 31, 1999 5:35 PM To: ITU-SG16(a)mailbag.cps.intel.com Subject: Re: H.320 gateways a MEGACO / ITU There's another problem - the use of PER combined with protocol- embedded addresses greatly complicates operation through firewalls. Not that I'm a fan of text-based protocols - I absolutely am not. But PER-encoded signaling streams could force the use of firewall proxies, which has unfortunate performance implications. I'm not certain that I understand the point about transcoding - it's going to have to take place, anyway, whether the megaco protocol is text-based or not. At 11:14 AM 3/31/99 +0200, Ami Amir wrote: >There are many who feel that ASN.1 is too heavy and complex for simple >devices, and should be avoided. This was one of the major reasons for the >emergence of SIP. Melinda Shore Member of the Scientific Staff Nokia IP Telephony 127 West State Street Ithaca, New York 14850 +1 607 273 0724 x81 (office) +1 607 275 3610 (fax) +1 607 280 0010 (mobile) shore(a)ithaca-viennasys.com

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Moneterey meeting report APC-1554
by Sakae OKUBO 01 Apr '99

01 Apr '99

Dear Q.12-14/16 experts, With completion of the liaison to SG8 (TD-39 revised), the report of the Monterey meeting (APC-1554) has also been completed. Please find the relevant files APC-1554b.zip and TD-39a.zip at the following directory of the PictureTel ftp site: ftp://standard.pictel.com/avc-site/9802_Mon or http://standard.pictel.com/ftp/avc-site/9802_Mon 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 ***********************************************************

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Re: Multimedia (was Re: Megaco Protocol - IETF/ITU conf call minu tes)
by Tom-PT Taylor 01 Apr '99

01 Apr '99

Single-medium contexts as a representaion scheme are orthogonal to the question of multimedia. Multimedia implies (a) multiple media types (b) coordination between them. If I have multiple contexts, each devoted to one medium, that satisfies (a). One suggestion on the call was to do that, then add a context attribute which linked together different contexts. This is a possible solution to (b). My personal feeling is that the single-medium context is a good direction to explore, because in the degenerate (audio-only) case it turns out simply. The open question, of course, is whether it introduces too many problems of coordination. I'm hoping to work through the two test cases I posed before the Minneapolis meeting to see. > -----Original Message----- > From: John Segers [SMTP:jsegers@LUCENT.COM] > Sent: Wednesday, March 31, 1999 7:11 AM > To: ITU-SG16(a)MAILBAG.INTEL.COM > Subject: Re: Multimedia (was Re: Megaco Protocol - IETF/ITU conf call > minutes) > > Mauricio, > > You are right that single medium contexts are simpler to reason about > services and call flows. But we must take care that we don't end up > with a protocol that cannot be extended to cover multimedia GWs. If > multimedia applications are within scope, the protocol document should > not contain a connection model that handles only audio. > > What do others think? Is multimedia in the scope of megaco/H.gcp? And > if so, is Paul's proposal general enough? Doesn't it lead to too much > overhead for single media GWs? I'd be interested to hear opinions. > > John Segers > > "Arango, Mauricio" wrote: > > > > Please disregard my previous message which by mistake I sent without > erasing > > editing. Apologies to the list members. > > > > Paul, > > > > I understand the rationale for your multiple media context. My > preference is > > the single medium context because it seems simpler for thinking about > > services and call flows. This seems to require more discussion. I > suggest we > > advance the protocol as proposed with single-medium contexts and revisit > > this later if necessary. > > > > Mauricio > > > > > -----Original Message----- > > > From: Paul Sijben [mailto:sijben@lucent.com] > > > Sent: Tuesday, March 30, 1999 2:45 PM > > > To: Arango, Mauricio > > > Cc: 'Greene, Nancy-M [CAR:5N10:EXCH]'; 'ITU-SG16(a)mailbag.intel.com'; > > > 'megaco(a)baynetworks.com' > > > Subject: Multimedia (was Re: Megaco Protocol - IETF/ITU conf call > > > minutes) > > > > > > > > > Mauricio, > > > > > > you write: > > > > It could be good idea to have some entity that ties > > > together multiple > > > > contexts, this was our experience in the Touring Machine > > > and we referred to > > > > it as "session". However, it may not be necessary for the > > > most common audio > > > > only operations, and for the sake of simplicity it may be > > > better to leave it > > > > as an option. > > > > > > I think you are absolutely right. We have been doing some > > > work on that and > > > have come up with the following which seems like a sensible > > > extention to > > > the H.gcp/MEGACOP work: > > > > > > Problem definition: > > > For multimedia calls you will have multiple media streams > > > representing > > > each of the users. these streams need to be appropriately > > > processed (maybe > > > mixed or something more clever) and synchronised. > > > > > > The current definition in the MEGACO I-D specifies that each > > > context only > > > has one type of medium. This makes the logical grouping of > > > terminations > > > belonging to one user difficult, creates issues with synchronisation > > > between media. It also makes it difficult to remove one user > > > or an entire > > > conference in one command. > > > > > > We have gone over several possible solutions, you can group > > > terminations > > > per user, and/or per medium and/or make some kind of links between > > > terminations or contexts which signify the synchronisation. > > > > > > What seems like a workable model is to allow multiple media > > > in one context > > > and have a matrix binding the terminations to the right > > > medium/user. So you > > > would get something like: > > > > > > context > > > > > > medium1 | M2 | ....| Mn > > > ------------------------------ > > > user1 | x | | | x > > > user2 | | x | | x > > > .......... > > > usern | x | x > > > where x==termination > > > > > > such a matrix could be a "scap paper" used by the MGW and MC > > > to keep track > > > of to which user and which medium each termination belongs. > > > One could set a > > > flag on terminations that one wants to synchronise. > > > > > > Naturally you would not need this for simple voice gateways so the > > > extentions needed to the protocol for this youl be optional. > > > > > > The extentions would look like: > > > > > > Commands: > > > We now have a command structure that states: > > > > > > ContextID > > > *Command(TerminationID ....) > > > > > > we would get: > > > > > > ContextID > > > [UserID] > > > *command( [MediaID] Termination ID....) > > > > > > so for example: > > > ContextID=3 > > > UserID=2 > > > add (MediaID=Video3, TerminationID=RTP:32424, ....) > > > modify (MediaID=Video3, TerminationID=*, SychWith:MediaID=Audio2) > > > > > > etc. > > > > > > A context could have the following properties: > > > - mode (unidirectional, bidirectional, mix, choose...) > > > - maxNumberOfUsers (e.g. 3) > > > - maxNumberOfMedia (e.g. 1 for a simple voice gateway) > > > > > > This extention would allow the removal of one medium or one > > > user from a > > > conference but not hamper "simple" operations. > > > > > > Paul > > > > > > "Arango, Mauricio" wrote: > > > > > > > > Nancy, > > > > > > > > Thanks for preparing the minutes. > > > > > > > > > > > > > > b. Raised by Mauricio Arango: you may want to be able to > > > > > create a context > > > > > with parameters before adding any terminations to it - (e.g. > > > > > turing machine) > > > > > > > > I want to clarify that I was not referring to Alan Turing's > > > grand work but > > > > to something colleagues and I did some years ago in > > > multimedia call control, > > > > called "Touring Machine". This effort developed a > > > connection model similar > > > > to the one in MEGACO's protocol and could be worth keeping > > > in mind as > > > > previous experience to help this effort. > > > > > > > > The January 1993 of the Communications of the ACM has an > > > article on the > > > > Touring Machine. Following is an excerpt desribing its > > > connection model > > > > (page 71): > > > > > > > > "The logical topology of a session is specified as a set of > > > typed connectors > > > > (see Figure 2). A connector represents a multiway transport > > > connection among > > > > endpoints (logical ports). A connection is an abstraction of a > > > > communications bridge, including point-to-point (two way) as well as > > > > multipoint connections. Since bridging is a medium-specific > > > operation, > > > > connectors are typed by medium. A session may have one or > > > more connectors > > > > per medium, with souce and sink endpoints from > > > participating clients. An > > > > endpoint represents a connector termination point. Endpoints are > > > > distinguished by medium, direction of flow, and the client > > > receiving or > > > > providing transport." > > > > > > > > In the above excerpt a "connector" is equivalent to > > > MEGACO's context and an > > > > "endpoint" is equivalent to MEGACO's termination. > > > > > > > > > c. Raised by a few people: we need to see whether we need a > > > > > meta definition > > > > > of a "call" in the MG, so that the MG can link together > > > > > related contexts. > > > > > May be needed for lipsynch between a call's video context and > > > > > its audio > > > > > context. Instead of introducing a callId, this could be done using > > > > > parameters on each context referring to the other one. > > > > > Benefit of a callId > > > > > is that the MGC can bring down the entire call by just > > > > > referring to the > > > > > callId. (Note: "call" may be the wrong word - if we need it, > > > > > let's try to > > > > > invent a new name). > > > > > > > > > > > > > It could be good idea to have some entity that ties > > > together multiple > > > > contexts, this was our experience in the Touring Machine > > > and we referred to > > > > it as "session". However, it may not be necessary for the > > > most common audio > > > > only operations, and for the sake of simplicity it may be > > > better to leave it > > > > as an option. > > > > > > > > Regards, > > > > > > > > Mauricio Arango > > > > > > > > > -----Original Message----- > > > > > From: Greene, Nancy-M [CAR:5N10:EXCH] > > > > > [mailto:ngreene@americasm01.nt.com] > > > > > Sent: Monday, March 29, 1999 8:54 PM > > > > > To: 'ITU-SG16(a)mailbag.intel.com'; 'megaco(a)baynetworks.com' > > > > > Subject: Megaco Protocol - IETF/ITU conf call minutes > > > > > > > > > > > > > > > Here are the minutes from the call today. Please email me any > > > > > corrections. I > > > > > tried to pair comments made with the person that made them - > > > > > I may have made > > > > > some errors, and I know I missed the names of some of the > > > > > people commenting. > > > > > > > > > > > > > > > > > > > > Nancy (ngreene(a)nortelnetworks.com) > > > > > ----------------------------------------------------------- > > > > > > > > > > Megaco Protocol presentation to IETF megaco and ITU SG16 > > > participants > > > > > March 29/99 10am-12pm EST > > > > > ================================================= > > > > > > > > > > Present: The number of ports being used went as high as 47, > > > > > and was about 45 > > > > > on average. Number of participants was higher since a number > > > > > of people were > > > > > sharing ports. > > > > > > > > > > Chair of the call: Glen Freundlich (ggf(a)lucent.com) > > > > > Minutes: taken by Nancy Greene (ngreene(a)nortelnetworks.com) > > > > > > > > > > NOTE: In keeping with IETF and ITU procedures, the audio call > > > > > cannot make > > > > > binding decisions. It is a tool for the chairs and > > > editors, and the > > > > > participants of both the IETF and ITU working groups, to > > > > > gauge support for > > > > > the protocol, and to raise issues with the protocol. Issues > > > > > may be raised in > > > > > either an audio call, or on the mailing list > > > > > (megaco(a)baynetworks.com). These > > > > > minutes are going to both the Megaco and ITU-SG16 mailing lists. > > > > > > > > > > Meeting summary: > > > > > -------------------------- > > > > > Glen Freundlich summed up results of the meeting. The goal of > > > > > the meeting > > > > > was two fold: > > > > > 1) it was the first opportunity for people to look at the > > > > > output from the > > > > > Megaco protocol design/drafting group. > > > > > 2) it was an opportunity for people to pose questions on > > > the draft. > > > > > > > > > > He saw no opposition to the connection model proposed in the > > > > > Megaco protocol > > > > > I-D > > > > > (ftp://www.ietf.org/internet-drafts/draft-ietf-megaco-protocol > > > > > -00.txt). > > > > > To date, the Megaco protocol I-D has been run through audio > > > > > call scenarios > > > > > for 3-way call, for call waiting, ... However, it needs to be > > > > > tested with > > > > > multimedia scenarios. Any input in this area is appreciated. > > > > > > > > > > Because there seems to be agreement on the connection model, > > > > > Bryan Hill, the > > > > > H.gcp editor, will start pulling related sections from the > > > > > Megaco protocol > > > > > I-D into H.gcp. > > > > > > > > > > Glen will hold another audio call next week to see where we > > > > > stand, and to > > > > > look towards adding more sections to H.gcp from the Megaco > > > > > protocol I-D. > > > > > > > > > > For the ITU-T SG16 May meeting, H.gcp needs to contain: > > > > > - a connection model > > > > > - a set of commands > > > > > - a start on parameters for those commands > > > > > - generic syntax > > > > > - and a list of issues to resolve. > > > > > > > > > > > > > > > Protocol timetable: > > > > > -------------------------- > > > > > IETF Megaco: > > > > > - Proposed Standard by summer/99 > > > > > - interoperability testing in fall/99 > > > > > - Draft Standard in Feb/2000 > > > > > > > > > > This matches up closely with the ITU-T SG16 schedule: > > > > > - planning to get H.gcp determined in May/99 > > > > > - planning to get H.gcp decided in Feb/2000 > > > > > > > > > > IETF/ITU collaboration: > > > > > ------------------------------- > > > > > Question raised: will the two protocols be identical? > > > > > > > > > > Tom Taylor proposes two options: > > > > > 1) SG16 and Megaco completely agree on the protocol > > > > > requirements. If this is > > > > > the case, the protocol will be identical > > > > > > > > > > 2) Each group has some requirements that are different from > > > > > the other group. > > > > > In this case, there would be agreement on a core > > > protocol, and then > > > > > additional parts would be defined by each group. > > > > > > > > > > BUT how to do this in practice? Tom said that if a huge > > > > > roadblock comes up > > > > > again, we would form a new design team to work out a solution. > > > > > > > > > > Tom asked whether the group on the call agreed that the > > > > > Megaco protocol I-D > > > > > was a reasonable basis for H.gcp. Feeling was that it is, but > > > > > that we need > > > > > to do multimedia call walkthroughs. Mike Buckley had some > > > > > concern about the > > > > > definition of a context, but thought that the basic model > > > is workable. > > > > > Mauricio Arango thought it was a good model for multimedia. > > > > > Ami Amir raised > > > > > issue about associating contexts. Glen asked the H.320 > > > > > experts to look at > > > > > the protocol and see if we need to modify the connection model. > > > > > > > > > > > > > > > Next audio call: > > > > > ---------------------- > > > > > Probably next Thursday April 8/99, same time. Confirmation of > > > > > date & time > > > > > and the call details will be out later this week. > > > > > > > > > > > > > > > Use of mailing lists: > > > > > --------------------------- > > > > > It was agreed that we would try to keep all technical > > > > > discussion of the > > > > > Megaco protocol on the megaco(a)baynetworks.com mailing list. > > > > > > > > > > Invitations to audio calls, and audio call minutes will be > > > > > sent to both the > > > > > megaco(a)baynetworks.com and to the ITU-SG16(a)mailbag.intel.com > > > > > mailing lists. > > > > > > > > > > Tom Taylor took the action of posting to each list, how to > > > > > join the other > > > > > one. > > > > > > > > > > Detailed minutes: > > > > > ------------------------ > > > > > Brian Rosen presented the Megaco protocol draft > > > > > (ftp://www.ietf.org/internet-drafts/draft-ietf-megaco-protocol > > > > > -00.txt). He > > > > > first noted that this draft is open for discussion. It is not > > > > > cast in stone. > > > > > If changes need to be made to any part, they will be > > > made, if they are > > > > > deemed necessary to satisfy the requirements of the protocol, > > > > > and agreed to > > > > > by the group. > > > > > > > > > > 1. New connection model > > > > > - concept of a termination - have permanent (e.g. DS0) and > > > > > ephemeral (e.g. > > > > > RTP port) terminations > > > > > - a termination is named with a terminationId, this name can > > > > > have wildcards, > > > > > for example to allow the MG to choose the actual physical > > > > > termination, or to > > > > > request notification of an event that occurs on any DS0 > > > > > - concept of a context - can add, subtract, modify > > > terminations in a > > > > > context. A context is created when the first termination is > > > > > added to it, and > > > > > goes away when the last termination is subtracted from it. > > > > > - a context can have parameters associated with it - for > > > > > example, a video > > > > > mixing context may have parameters to describe how the video > > > > > is to be mixed > > > > > - mosaic, or current speaker/last speaker, ... > > > > > - a termination class defines parameters on a typical > > > > > termination - e.g. DS0 > > > > > Termination Class, RTP Termination Class > > > > > - Signals can be attached to a termination class, events can > > > > > occur at a > > > > > termination class, and the MGC can specify which ones it > > > wants to be > > > > > notified about. > > > > > - packages define signals and events > > > > > - a termination class can have more than one package that > > > apply to it > > > > > - event naming structure allows package name to be put in > > > > > front of the event > > > > > name > > > > > - question: how do you apply a call waiting tone? - answer - > > > > > it is a signal > > > > > that you apply to a termination > > > > > > > > > > 1.1 Proposed Changes and Issues: > > > > > a. Tom Taylor proposed a more general definition for > > > context: every > > > > > termination in a context has connectivity with all other > > > > > terminations in the > > > > > context. > > > > > > > > > > b. Raised by Mauricio Arango: you may want to be able to > > > > > create a context > > > > > with parameters before adding any terminations to it - (e.g. > > > > > turing machine) > > > > > - may want to mark a context with the max # of terminations > > > > > at creation > > > > > time. - BUT this may bring lack of flexibility - may be > > > > > better to let the MG > > > > > decide, as new terminations are added to a context, whether > > > > > it is able to > > > > > mix them in. For example, instead of marking a context with > > > > > one particular > > > > > type of codec, it is more flexible to let the MG decide what > > > > > transcoding > > > > > needs to be done in a context as a function of the types of > > > > > terminations > > > > > added to it. > > > > > > > > > > c. Raised by a few people: we need to see whether we need a > > > > > meta definition > > > > > of a "call" in the MG, so that the MG can link together > > > > > related contexts. > > > > > May be needed for lipsynch between a call's video context and > > > > > its audio > > > > > context. Instead of introducing a callId, this could be done using > > > > > parameters on each context referring to the other one. > > > > > Benefit of a callId > > > > > is that the MGC can bring down the entire call by just > > > > > referring to the > > > > > callId. (Note: "call" may be the wrong word - if we need it, > > > > > let's try to > > > > > invent a new name). > > > > > > > > > > d. Raised by Steve Davies: with H.320, the MG has one > > > > > physical termination > > > > > with audio, video and data on it - can a termination be in > > > > > more than one > > > > > context? no - so need to separate the different media out of > > > > > this physical > > > > > termination before creating the contexts. > > > > > > > > > > e. Raised by Tom Taylor: need to see whether it is > > > feasible to have > > > > > decomposed H.320 gateways - if it is necessary (people say > > > > > yes), then need > > > > > to be sure the Megaco protocol can handle it. > > > > > > > > > > > > > > > 2. Commands > > > > > - grouped into commands within an action per context, and > > > one or more > > > > > actions are grouped into a transaction. Transaction is > > > all or nothing. > > > > > - Add, Modify, Subtract each can contain local and remote > > > terminiation > > > > > descriptors, signalling descriptor, an events descriptor, and > > > > > a digit map > > > > > descriptor > > > > > - question on how to change an event description for a > > > > > termination - answer: > > > > > use Modify - can do it within a context, or outside a context > > > > > - if it is > > > > > outside the context (i.e. using the NULL context), then that > > > > > is how you > > > > > change the default parameters for that termination. > > > > > - MGCP's NotificationRequest is now covered in Modify > > > > > > > > > > 3. Multimedia and Contexts and Terminations > > > > > - a termination only belongs to one context > > > > > - for multimedia, there is one context per media type > > > > > - just as you have separate RTP flows for different media > > > > > types, you have > > > > > separate contexts. > > > > > > > > > > 3.1 Issues > > > > > a. Paul Sijben noted that when you try to use the Megaco > > > protocol with > > > > > H.320, there may be problems with the model - Paul will bring > > > > > these up on > > > > > the mailing list. > > > > > > > > > > Also, see Issue c in 1.1 above. > > > > > > > > > > 4. H.245 & SDP > > > > > - Tom Taylor explained that H.245 has at least 2 purposes: 1) > > > > > for capability > > > > > negotiation, and 2) for specification of open logical > > > > > channel. The scope of > > > > > the Megaco protocol is 2). Capability negotiation may use > > > > > H.245 between > > > > > MGCs, but the Megaco protocol is between MGC and MG. SDP may > > > > > be good enough > > > > > to be used between the MGC and the MG. Discussion still open > > > > > here. Need to > > > > > allow for an environment where H.245 may not be involved. > > > > > - with H.263 - H.245 provides a tag to link together 2 RTP > > > > > streams - need to > > > > > be able to carry this tag from the MGC to the MG. > > > > > > > > > > 5. underspecifying termination descriptors > > > > > - can be used as a way to tell the MG to use default > > > values for the > > > > > termination > > > > > - a termination learns its default values at MG boot-up time > > > > > - MGC can change these values using Modify with context > > > set to NULL. > > > > > > > > > > 6. underspecifying terminationIds > > > > > - provides a way of setting default parameters for a T1 > > > for example > > > > > > > > > > 7. Case: two audio contexts - in different MGs, and in the same MG > > > > > - can the connection model handle this? Yes > > > > > - protocol should need to keep track of where resources are. > > > > > - it is up to the MGC to know what contexts are associated > > > > > with a call. > > > > > > > > > > 8. overview of Audit, Notify, ServiceChange > > > > > - ServiceChange - MG can use it upon reboot, to register > > > > > itself with an MGC > > > > > - MG knows which MGC to send this msg to from some method > > > > > outside the scope > > > > > of this protocol (pre-provisioned, for example). > > > > > - MGC learns capabilities of MG using Audit. - can learn codecs > > > > > > > > > > 8.1 Issue > > > > > - need a way for MGC to learn the QUANTITY of codecs an MG has! > > > > > > > > > > 9. overview of Security > > > > > - this is security between an MGC and an MG > > > > > - interim method is specified for when an MG does not have IPSEC > > > > > > > > > > 10. Question on scope of the protocol > > > > > - check the requirements draft: > > > > > ftp://standards.nortelnetworks.com/megaco/docs/minn99 > > > > > - Steve Davies brought up point that some aspects of the > > > > > Megaco protocol > > > > > overlap with Policy server protocol proposals. > > > > > > > > > > 11. Can MG do coded renegotiation? > > > > > - David Featherstone asked if an MG can negotiate use of a > > > > > new codec on its > > > > > own > > > > > - Brian Rosen answered that with AAL2 profiles, the MG can > > > > > > > > > > Issue: > > > > > a. MGC may need to be involved - for example if the Quality > > > > > goes down too > > > > > low, call may no longer be billable. Solution - create an > > > > > event to notify > > > > > the MGC for this case. > > > > > > > > > > 12. How does the MGC find out RTP interfaces? > > > > > - should be able to do this using Audit in the NULL context. > > > > > > > > > > 13. IVR - still open for discussion > > > > > - view IVR as a termination > > > > > - issue is how much signalling effort do you need to add to > > > > > the protocol? > > > > > - simply playing msgs is ok - they just look like events > > > > > - problem is when you want to put time and money values into > > > > > it for example, > > > > > you have x minutes left on your calling card. - this may be > > > > > out of the scope > > > > > of the Megaco protocol > > > > > > > > > > 14. QoS reservation > > > > > - needs more discussion > > > > > > > > > > ****see Meeting summary above for audio call conclusions. > > > > > > > > > > end of minutes. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -------------------------------------------------------------- > > > > > ------------ > > > > > Nancy M. Greene > > > > > Internet & Service Provider Networks, Nortel Networks > > > > > T:514-271-7221 (internal:ESN853-1077) E:ngreene@nortelnetworks.com > > > > > > > > > > > -- > > > Paul Sijben Telno:+ 31 35 687 4774 Fax:+31 35 687 5954 > > > Lucent Technologies Home telno: +31 33 4557522 > > > Forward Looking Work e-mail: sijben(a)lucent.com > > > Huizen, The Netherlands internal http://hzsgp68.nl.lucent.com/ > > > > > -- > John Segers email: jsegers(a)lucent.com > Lucent Technologies Room HE 344 > Dept. Forward Looking Work phone: +31 35 687 4724 > P.O. Box 18, 1270 AA Huizen fax: +31 35 687 5954

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