deployment

   o  (A05) Number of dialogs to maintain per watcher - The number of
      the SUBSCRIBE dialogs that are maintained per watcher. if a dialog
      optimization is not assumed this number is equal to A04, otherwise
      it is 1

   o  (A06) Number of watchers in a federated presence domain - The
      number of watchers in one presence domain that watch presentities
      in the other domain.  The number here varies according to the
      assumptions for a specific deployment




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   o  (A07) Initial SUBSCRIBE/200 per watcher = A05*2 (message and an OK

   o  (A08) Initial NOTIFY/200 per watcher = A05*2 (message and an OK)

   o  (A09) Total initial messages = (A07+A08)*A06

   o  (A10) NOTIFY/200 per watched presentity = (A02*A01*A04*2) (message
      and an OK)

   o  (A11) SUBSCRIBE/200 refreshes = (A01/A03)*A05*2 (message and an
      OK)

   o  (A12) NOTIFY/200 due to subscribe refresh - In a deployment where
      the notification optimization is not deployed this number will be
      ((A01/A03)*A05), otherwise it is 0

   o  (A13) Number of steady state messages = (A10+A11+A12)*A06

   o  (A14) SUBSCRIBE termination = A05*2 (message and an OK)

   o  (A15) NOTIFY terminated = A05*2 (message and an OK)

   o  (A16) Number of sign-out messages = (A14+A15)*A06

   o  (A17) Total messages between domains (both directions where users
      from domain A subscribe to users from domain B and vice versa)=
      (A09+A13+A16)*2

   o  (A18) Total number of messages / second = A17/A01/3600 (seconds in
      hour)

   o  (A19) Total number of K bytes per second.  Assuming 1K bytes per
      SUBSCRIBE/200 pair and 4K bytes per NOTIFY/200 pair.  Note that in
      reality the NOTIFY size may be much bigger but using partial
      NOTIFY should reduce the size considerably

<SPAN class=h3><A name=section-3.4>3.4</A>.  SIMPLE with no optimizations</SPAN>

   The following table uses some common presence characteristics to
   demonstrate the effect these factors have on state and message rate
   within a presence domain using base SIMPLE protocols without any
   proposed optimizations.  In this example, there are two presence
   domains, each with 20,000 federating users with an average of 4
   contacts in the peer domain







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   (A01) Subscription lifetime (hours)...........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A02) Presence state changes / hour...........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-3">3</A>
   (A03) Subscription refresh interval / hour....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-1">1</A>
   (A04) Total federated presentities per watcher................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-4">4</A>
   (A05) Number of dialogs to maintain per watcher...............<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-4">4</A>
   (A06) Number of watchers in a federated presence domain..20,000

   (A07) Initial SUBSCRIBE/200 per watcher.......................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A08) Initial NOTIFY/200 per watcher..........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A09) Total initial messages............................320,000

   (A10) NOTIFY/200 per watched presentity.....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-192">192</A>
   (A11) SUBSCRIBE/200 refreshes................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-64">64</A>
   (A12) NOTIFY/200 due to subscribe refresh....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-64">64</A>
   (A13) Number of steady state messages.................6,400,000

   (A14) SUBSCRIBE termination...................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A15) NOTIFY terminated.......................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A16) Number of sign-out messages.......................320,000

   (A17) Total messages between domains.................14,080,000
   (A18) Total number of messages / second.....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-489">489</A>
   (A19) Total number of bytes / second on the wire..........830KB

                  Figure 1: SIMPLE with no optimizations

<SPAN class=h3><A name=section-3.5>3.5</A>.  SIMPLE with suggested optimizations</SPAN>

   The same analysis provided above is repeated here with the assumption
   that both the dialog and the notification optimizations are applied.
   Note that while the sign-in (ramp up) and sign-out messages flows are
   positively affected, the steady state rates are not.

   The optimizations enable the creation of a single dialog to the other
   domain from each watcher for the set of presentities it is watching.
   The optimizations also enable that there will be no need for a NOTIFY
   upon refreshing a SUBSCRIBE since the NOTIFY should not be sent in
   the refresh since it should be the same one that was sent when there
   was a state change for the presentity.












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   (A01) Subscription lifetime (hours)...........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A02) Presence state changes /hour............................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-3">3</A>
   (A03) Subscription refresh interval / hour....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-1">1</A>
   (A04) Total federated presentities per watcher................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-4">4</A>
   (A05) Number of dialogs to maintain per watcher...............<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-1">1</A>
   (A06) Number of watchers in a federated presence domain..20,000

   (A07) Initial SUBSCRIBE/200 per watcher.......................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-2">2</A>
   (A08) Initial NOTIFY/200 per watcher..........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-2">2</A>
   (A09) Total initial messages.............................80,000

   (A10) NOTIFY/200 per watched presentity.....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-192">192</A>
   (A11) SUBSCRIBE/200 refreshes................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-16">16</A>
   (A12) NOTIFY/200 due to subscribe refresh.....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-0">0</A>
   (A13) Number of steady state messages.................4,160,000

   (A14) SUBSCRIBE termination...................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-2">2</A>
   (A15) NOTIFY terminated.......................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-2">2</A>
   (A16) Number of sign-out messages........................80,000

   (A17) Total messages between domains..................8,640,000
   (A18) Total number of messages / second.....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-300">300</A>
   (A19) Total number of bytes / second on the wire..........571KB

                    Figure 2: SIMPLE with optimizations

<SPAN class=h3><A name=section-3.6>3.6</A>.  Presence Federations</SPAN>

   While these scalability issues exist in any large deployment, certain
   characteristics make the deployment conducive to the existing
   resource- list optimizations, and others have characteristics that
   cannot be exploited with the existing SIMPLE model.  Following is a
   list of federation relationships that have varying usage
   characteristics.  For each, a message rate and bandwidth table is
   provided reflecting typical changes message rates.  Those
   characteristics can alter the overall effectiveness of existing
   optimizations.

<SPAN class=h4><A name=section-3.6.1>3.6.1</A>.  Widely distributed inter-domain presence</SPAN>

   In some environments presence federation may be very common, perhaps
   even more common than intra-domain presence.  An example of this type
   of environment is a small ISV or public server.  Users in that small
   ISV are not likely to subscribe to the presence of other users in the
   their server since they do not necessarily have any relationship with
   each other aside from receiving service from the same provider.  They
   are much more likely to be subscribed to the presence of users in one
   of the federated domains (whether in consumer domains, academic,



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   other ISVs, etc).  Common characteristics of this deployment are:

   o  Federated subscriptions are the majority of subscription traffic

   o  Individual users are likely to subscribe to multiple users in any
      one domain

   o  The intersection of users in the deployment watching the same
      presentities is quite small (i.e., probability that watchers in
      the domain subscribe to the same presentity is low)

   To account for the extraordinarily high percentage of federation
   traffic, the number of federated presentities is increased to 20.
   The number of watchers in the domain could also be adjusted to
   account for an expected larger community of users being peered with,
   it is omitted here for simplification

   The first table below provides the calculations without optimizations
   the second table provides the calculations with optimization.  Note
   that the number of messages per second decreases by a quarter with
   the optimizations but it is still quite big.  It is interesting to
   see that the bandwidth is almost the quarter of the bandwidth when
   optimizations are applied.

   (A01) Subscription lifetime (hours)...........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-8">8</A>
   (A02) Presence state changes / hour...........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-3">3</A>
   (A03) Subscription refresh interval / hour....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-1">1</A>
   (A04) Total federated presentities per watcher...............<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-20">20</A>
   (A05) Number of dialogs to maintain per watcher..............<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-20">20</A>
   (A06) Number of watchers in a federated presence domain..20,000

   (A07) Initial SUBSCRIBE/200 per watcher......................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-40">40</A>
   (A08) Initial NOTIFY/200 per watcher.........................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-40">40</A>
   (A09) Total initial messages..........................1,600,000

   (A10) NOTIFY/200 per watched presentity.....................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-960">960</A>
   (A11) SUBSCRIBE/200 refreshes...............................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-320">320</A>
   (A12) NOTIFY/200 due to subscribe refresh...................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-320">320</A>
   (A13) Number of steady state messages................32,000,000

   (A14) SUBSCRIBE termination..................................<A href="http://tools.ietf.org/html/draft-ietf-simple-interdomain-scaling-analysis-00#page-40">40</A>