W4140 Network Laboratory Lecture 10 Nov 30 - Fall 2006 Shlomo Hershkop Columbia University. Announcements. Phase I due today I will get you feedback over the week Start to plan for phase II Thanksgiving No lab scheduled Lab 7 report due on Monday after break Please do reading Any issues ?.
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W4140 Network LaboratoryLecture 10Nov 30 - Fall 2006Shlomo HershkopColumbia University
University of Oregon
Instead of sending a separate copy of the data for each recipient, the source sends the data only once, and routers along the way to the destinations make copies as needed.
Unicast does mass mailings; multicast does chain letters.
“Data” here could be
Internet News “Melt-down”:Web Site Performance 9:00 AM to 10:00 AM
Site% Users able to access
(source: Keynote’s Business Performance / Interactive Week 9/17/2001)
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]>
Sudden increase in Multicast traffic of at least 1000 group members
BANDWIDTH SAVED: in excess of 1 Gbps vs. unicast
Crowds viewing the 9/11 multicasts at Networld+Interop
U. of HawaiiInteractive TV Locations and Staff Sites
e.g., video server
IP source = IP unicast addr
Ethernet source = MAC addr
IP destination = IP multicast addr
Ethernet dest = MAC addr
source = origin of multicast stream
multicast address = an IP address in the Class D range (126.96.36.199 – 188.8.131.52), used to refer to multiple recipients.A multicast address is also called a multicast groupor channel.
multicast stream = stream of IP packets with multicast address for IP destination address. All multicast uses UDP packets.
receiver(s) = recipient(s) of multicast stream
tree = the path taken by multicast data. Routing loops are not allowed, so there is always a unique series of branches between the root of the tree and the receivers.