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   Copyright (C) The IETF Trust (2007).








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<SPAN class=grey>Internet-Draft      Problem Statement for SIP/SIMPLE       February 2007</SPAN>


Abstract

   The document analyses the traffic that is generated due to presence
   subscriptions between domains.  It is shown that the amount of
   traffic can be extremely big.  In addition to the very large traffic
   the document also analyses the affects of a large presence system on
   the memory footprint and the CPU load.  Several suggested
   optimization to the SIMPLE protocol are analysed with the possible
   impact on the load.


Table of Contents

   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-1">1</A>.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-4">4</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-2">2</A>.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-5">5</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3">3</A>.  Message Load . . . . . . . . . . . . . . . . . . . . . . . . .  <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-7">7</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.1">3.1</A>.  Known Optimizations  . . . . . . . . . . . . . . . . . . .  <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-7">7</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.2">3.2</A>.  Assumptions  . . . . . . . . . . . . . . . . . . . . . . .  <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-7">7</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.3">3.3</A>.  Analysis . . . . . . . . . . . . . . . . . . . . . . . . .  <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.4">3.4</A>.  SIMPLE with no optimizations . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-10">10</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.5">3.5</A>.  SIMPLE with suggested optimizations  . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-11">11</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.6">3.6</A>.  Presence Federations . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-12">12</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.6.1">3.6.1</A>.  Widely distributed inter-domain presence . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-12">12</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.6.2">3.6.2</A>.  Associated inter-domain presence . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-14">14</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.6.3">3.6.3</A>.  Very large network peering . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-15">15</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-3.6.4">3.6.4</A>.  Intra-domain peering . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-17">17</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-4">4</A>.  Resource List Service  . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-20">20</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-5">5</A>.  State Management . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-22">22</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-5.1">5.1</A>.  State Size Calculations  . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-23">23</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-5.1.1">5.1.1</A>.  Tiny System  . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-23">23</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-5.1.2">5.1.2</A>.  Medium System  . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-23">23</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-5.1.3">5.1.3</A>.  Large System . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-23">23</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-5.1.4">5.1.4</A>.  Very Large System  . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-24">24</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-6">6</A>.  Processing complexities  . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-25">25</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-6.1">6.1</A>.  Aggregation  . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-25">25</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-6.2">6.2</A>.  Partial Publish and Notify . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-25">25</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-6.3">6.3</A>.  Filtering  . . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-26">26</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-6.4">6.4</A>.  Privacy  . . . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-26">26</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7">7</A>.  Possible Optimizations . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-27">27</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.1">7.1</A>.  Common NOTIFY for multiple watchers  . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-27">27</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.1.1">7.1.1</A>.  Privacy filtering  . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-27">27</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.1.2">7.1.2</A>.  NOTIFY failure aggregation . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-28">28</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.1.3">7.1.3</A>.  Transferring the watcher list  . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-28">28</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.1.4">7.1.4</A>.  Message flow example . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-29">29</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.1.5">7.1.5</A>.  SIP message examples for common NOTIFY . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-31">31</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.2">7.2</A>.  Aggregation of NOTIFY messages (Batched notification)  . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-32">32</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.2.1">7.2.1</A>.  Extracting and sending individual NOTIFY using
               Aggregated NOTIFY message body . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-32">32</A>



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       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.2.2">7.2.2</A>.  Subscription termination and failure indication in
               NOTIFY delivery  . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-33">33</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.2.3">7.2.3</A>.  Message flow example . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-33">33</A>
       <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.2.4">7.2.4</A>.  SIP message flow example for batched notification  . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-35">35</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.3">7.3</A>.  Timed presence . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-37">37</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.4">7.4</A>.  On-Demand presence (Fetch or Pull Model) . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-38">38</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.5">7.5</A>.  Adapting the subscription rate . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-38">38</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-7.6">7.6</A>.  Other Optimizations  . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-38">38</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-8">8</A>.  Extremely Optimized  Model . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-41">41</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-9">9</A>.  Suggested Requirements . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-43">43</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-10">10</A>. Conclusions  . . . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-45">45</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-11">11</A>. Security Considerations  . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-46">46</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-12">12</A>. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-47">47</A>
   <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-13">13</A>. References . . . . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-48">48</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-13.1">13.1</A>. Normative References . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-48">48</A>
     <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#section-13.2">13.2</A>. Informational References . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-48">48</A>
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-50">50</A>
   Intellectual Property and Copyright Statements . . . . . . . . . . <A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-52">52</A>

































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<SPAN class=h2><A name=section-1>1</A>.  Requirements notation</SPAN>

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [<A title='"Key words for use in RFCs to Indicate Requirement Levels"' href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#ref-1">1</A>].














































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<SPAN class=h2><A name=section-2>2</A>.  Introduction</SPAN>

   The document analyses the traffic that is generated due to presence
   subscriptions between domains.  It is shown that the amount of
   traffic can be extremely big.  In addition to the very large traffic
   the document also analyses the affects of a large presence system on
   the memory footprint and the CPU load.  Several suggested
   optimization to the SIMPLE protocol are analysed with the possible
   impact on the load.

   Although this document is an analysis document and not a BCP
   document, several possible optimizations and directions are listed in
   addition to an initial set of requirements for what should be the
   characteristic of the solution to the problem stated in the document

   This document is intended to be used by the SIMPLE WG in order to
   work on possible solutions that will make the deployment of a
   presence server more reasonable task.  Note that the document does
   not try to compare the SIP based presence server to other types of
   presence servers but only analyses the SIP based presence server.  It
   is very likely that similar scalability issues are inherent to the
   deployment of presence systems and not to a certain protocol.

   The document discusses the following areas.  In each area we try to
   show the complexity and the load that the presence server has to
   handle in order to provide its service.

   o  Messages load - By computing the number of messages that are
      required for connecting presence systems the document shows that
      the number of messages is very big and it is quite obvious that
      some optimizations are needed.  In addition we also show that the