Multicast After 9/11/2001
NANOG 23
Marshall Eubanks
[email protected]
Rich Mavrogeanes
[email protected]
Prashant Rajvaidya
[email protected]
Internet News “Melt-down”
9/11/2001
Web Site Performance 9:00 AM to 10:00 AM
Site
ABCNews.com
CNN.com
NYTimes.com
USAToday.com
MSNBC.com
% Users able to access
0%
0%
0%
18 %
22 %
(source: Keynote’s Business Performance /
Interactive Week 9/17/2001)
Internet News Performance
9/11/2001
Of course, the “melt-down” was caused by the
incredible demand for news after the attacks.
 Unicast Streaming web sites suffered similar
problems, at least from anecdotal evidence
 By contrast, multicast performed well

– Large Increase in traffic
– Roughly 1 Gigabit per second saved at peak
– Over time, the multicast peering mesh degraded, but
this was NOT due to increased traffic
Eyewitness Accounts
“We had a large plasma screen in the iLabs {at Networld+Interop] intended to demonstrate high
rate HDTV over I2. We came in Tuesday morning and were preparing for the first day of the
show when word came in about the initial plane crash into the towers. Our I2 Lead, Roy
Hockett was able to switch the stream to a CNN broadcast from UMich. We began attracting
exhibitors to the display even before the showfloor opened. Once the attendees were on the
floor, the crowd had grown to well over a hundred.
“By this point, three things had happened. The crowds around the one display had grown so large
as to constitute a fire hazard, all the major news web sites had completely melted down, and
CNN was being multicast from several sources. We then started loading multicast tools on
every PC in the NOC, from the one driving the large video wall to people's individual laptops.
By 10:30 (about half an hour after the floor opened) we had at least 3 large displays as well as a
number of normal monitors turned out towards the plexiglass walls.
“Soon after, we had a good number of exhibitors come and ask how to get "the CNN viewer
software".
Jim Martin, <[email protected]>
“More than 1,000 copies of StreamPlayerII, our multicast MPEG viewer, were downloaded or
handed out on disk between 9/11 and 9/12. We normally average 20 to 100 per day.”
Rich Mavrogeanes <[email protected]>
Viewership
Sudden increase in
Multicast traffic of at least
1000 group members
–Mostly viewing VBrick’s
television broadcast
–Measured Viewership >
830
–But each measured point
could have many
individual viewers since
they multicast locally
BANDWIDTH SAVED IN
EXCESS OF 1 GIGABIT /
SEC. VS UNICAST
Crowds viewing the 9/11 multicasts at
Networld+Interop
Multicast Activity
at FIX-West / Mantra
Purple is
# of
group
members
^ 9/11 attack
Note that extra traffic seems to be mostly US - also not all multicast traffic is
visible to Mantra
Attack traffic spurt was so rapid and unusual that we first thought it was a
MSDP storm !
from http://www.caida.org/tools/measurement/Mantra/session-mon/session-mon.html
Multicast Receivers
Week of 9/10
^ 9/11 attack
Two independent monitoring efforts on two coasts saw very similar audience bursts after the attacks
Multicast Receivers
in September
^ 9/11 attack
^ 9/11 attack
Multicast
Activity on 9/11 and after

Sudden increase in Mantra traffic of
1000 group members
>
– Most of these seem to be television viewers
– Known TV viewership > 830
– Bandwidth saved approaches or exceeds 1
Gigabit / sec.

Performance as seen from MCT was good.
The Stability of Multicast





How did Multicast Connectivity behave under the
attack?
We (Multicast Technologies) monitor multicast
connectivity as seen by MBGP from our AS.
There were no apparent problems on 9/11
However, there were problems starting on 9/13 when
the backup power for 25 Broadway went down.
Our connectivity suffered from this.
Multicast Redundancy

We (Multicast Technologies) have 3 connections into
the multicast enabled Internet.
 Of the 4642 MBGP prefixes advertised to us recently,
28% had only one route !
Number Routes
Number Prefixes
%
1
1280
28 %
2
2445
53 %
3
917
20 %
The Multicast Mesh Needs to be More Robust
Multicast As the
Generators Ran Out…
< 25 Broadway Failure
^Attack
^ Alternate Access through AUCS
Conclusions

Multicast Met a Real Need after the 9/11
attacks
– Over 800 video users (at least)
– ~ 1 Gigabit / sec of bandwidth saved (at least)

Multicast passed its baptism under fire
– Availability when other sites were spotty at best

The Multicast mesh and peering need to be
made more robust.