AOL IM Traffic Statistics - Corrected and Expanded

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From: Stephen D. Williams (
Date: Mon Jun 19 2000 - 20:28:46 PDT

According to public AOL statements:

4 Million simultaneous users at peak
1 Billion IMs/day
2 MB/second = 173 GB/day = 20Mb+ avg. traffic, full duplex loading


Nearly 12000 IMs/sec, average. My heuristic for public Internet services is
that peak is 4 times average. That means 48000 IMs/sec avg. sustained at

As per Adam Beberg:
"There are 91M AOL-IM users, 23M of which actually subscribe to AOL.
Add in the other "services" that use AOL-IM on the sneaky-sneak.
That's only 10 per user per day. not so unreasonable...
dont even ask how many i sent in a day"

My guess would be that in any given day there are 120 Million sessions for 50M
unique users. This guess would indicate 8.3 IMs per session and 20 IMs per
person, per day, average. Median is much harder to guess at, probably fairly

120M sessions/day means that there are 240M update triggers to BuddyList per
day. Let's guess that a current average for buddies-per-list is 15. Let's
further posit that on average watchers number 15%, or 2.25 watchers for each
event. That's 240M * 2.25 BuddyList updates + 240M update triggers + 120M
subscription lists. Note that lists can be multiple messages from the client
and/or when routed to multiple servers. Grand total BuddyList related events:
900M. That makes 88000 communication events per sec. at peak, sustained.

If the 2MBytes/Sec is average and not peak, this means that each communication
event is 192 bytes on average including protocol. This is barely enough to
handle the headers in some of the proposals.

The bandwidth is much less than I would have thought.

Bulk bandwidth for colocated servers starts at about $1000/Mbit and goes down
with bulk.

Adam also mentioned:
"Most bandwidth is peer-peer is {sic} you do it right, or anywhere near

In my estimation, this will be available to fewer than 50% of all pairs
capable of using peer-peer communication mechanisms. Fewer if you need
bidirectional connectivity. The prevalence of a number of Internet practices
causes this to in fact be a growing number as dialup users dwindle. Nearly
all broadband connections will probably have restrictions on incoming
connectivity by default due to the use of NAT routers. For security reasons,
nearly all business users will have severe restrictions on incoming
connectivity. Significant, and annoying, numbers of companies have severe
restrictions on outgoing connections. A large telco and it's subsidiaries
force everything through an HTML proxy that strips all Java AND Javascript.
One of the larger insurance companies blocks (or at least used to block) all
commercial sites from their employees lest they shop at work, including their
own website!

For something like IMPP it's not reasonable to work only for those with
unhindered Internet connections in the name of slightly better performance
(hence the current leaning toward TCP to Relays/Proxies/Servers).

The point is that what is technically right is not necessarily the correct
solution to the current opportunity. There are a number of players who have
overriding reasons to make decisions that would prevent more elegant

Personally, I would rather suffer with video conferencing through TCP/IP than
to not have it at all. In fact, I'm currently behind an ISDN router that does
NAT to my network and doesn't seem to have another mode. Some day when Bell
Atlantic finally installs my sDSL with fixed IP's I'll be the one grumbling
about other's crippled connections. One solution that makes this reasonable
is to have more or less generic event/stream proxies at every ISP that you
connect through locally. This is the IMPP model for connectivity and routing,
although many participants feel that media or file streaming is completely
outside the IMPP scope.

Also note that AOL's estimated to handle 20-30% of the world's Email or
Internet Email (it's not clear, must be the latter).


-- - Revolutionary E-Business Communication Stephen D. Williams  Senior Consultant/Architect
43392 Wayside Cir,Ashburn,VA 20147-4622 703-724-0118W 703-995-0407Fax  Jan2000

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