[Robustness] Minutes of the Apr 20 call

charles Agboh agboh at HELIOS.IIHE.AC.BE
Fri Apr 21 14:50:06 EDT 2000


Hi all,

what is ddp and where can i get information on it.

charles

Terry L Anderson wrote:

> Minutes of the Apr 20, 2000 Robustness teleconference call, 11:00 EDT
>
> Present on the call:
> Tim Chen & Mahesh Bhan (and perhaps others)- Trillium
> Tim Sipsey - Aspect
> Rex Coldren & Terry Anderson - Lucent
> Randy Stewart & Qiaobing Xie - Motorola
> Paul Jones - Cicso
>
> Next Meeting: Apr 27, 2000 EDT (15:00 UT/GMT) (see below for details).
>
> Agenda:
> 1. continue discussion of SCTP/DDP vs Annex E discussion
> 2. Plans for Osaka
> 3. next meeting
>
> (Participants - if I have misrepresented the discussion, feel free to
> comment to the list)
>
> SCTP/DDP vs Annex E:
> We continued earlier discussions on these underlying structures.  It
> appears that we have two basic models:
> 1. SCTP/DDP based transport using DDP and a distributed/shared memory
> scheme (based on DDP) to allow a cluster of servers to provide a
> fault-tolerant "element", nearly transparent to the H.323 application
> layer.  The application layer would have to "checkpoint" critical data
> at defined points so that backup servers can take over function with
> full state information.  Message delivery is reliable end-to-end if each
> element-cluster guarantees delivery by a member of the cluster once
> acknowledged to the sender through SCTP.
>
> 2. Annex E-based transport with added mechanism for end-to-end message
> acknowledgement.  Originator of a message would resend if far-end ack
> NOT received.  How Annex E and application layer cooperated for this
> end-to-end ack, to be clarified.  This ensures that the two end points
> agree on call state.  We still need connection reestablishment
> mechanisms for backup elements and state recovery through application
> layer mechanisms (perhaps similar to Radvision proposal at Geneva).
>
> There are intermediate solutions (DDP on Annex E, use of end-to-end ack
> with DDP-fault tolerant clusters, ...) that have not been rejected.
>
> We decided that choose between these models and to make better progress
> we needed more precise statements of the solutions.  See plans for this
> under Next Meeting.
>
> Plans for Osaka:
> We did not complete this.  It appears likely that we can have a document
> to present based on the SCTP/DDP mechanism.  We may be able to complete
> a document based on Annex E.  We have NOT determined whether we will
> choose or present BOTH with the study group.  We will need to re-assess
> this on the next call.
>
> Next Meeting:
> Apr 27, 11:00 EDT (15:00 UT/GMT).
> Randy & Qiaobing will provide a draft of their model for backup GK
> recovery using SCTP/DDP, including, if possible, a way to allow GW to
> recover SCTP to backup without using DDP (DDP only between members of
> the server pool).
>
> Paul and Trillium participants will try to have a draft of a mechanism
> using Annex E & end-to-end confirmations.
>
> --
> ------------------------------------------------------------
> Terry L Anderson              mailto:tla at lucent.com
> Tel:908.582.7013   Fax:908.582.6729
> Pager:800.759.8352 pin 1704572   1704572 at skytel.com
> Lucent Technologies/ Voice Over IP Access Networks/ Applications Grp
> Rm 2B-121, 600 Mountain Av, Murray Hill, NJ 07974
> http://its.lucent.com/~tla (Lucent internal) http://www.gti.net/tla

--

Charles Agboh

Universite Libre de Bruxelles
Service Telematique et Communication
Bd du Triomphe, CP 230
B-1050 Brussels
Belgium

Tel. +32 2 6505717
Fax. +32 2 6505088, +32 2 6293816
RFC-822 : agboh at helios.iihe.ac.be

----------------------------------
"Perilous to us all are the devices of an art deeper than we possess
ourselves." --J.R.R Tolkien, The Two Towers

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