CS 204: Multicast Jiasi Chen Lectures: MWF 12:10-1pm in WCH 139 - - PowerPoint PPT Presentation
CS 204: Multicast Jiasi Chen Lectures: MWF 12:10-1pm in WCH 139 http://www.cs.ucr.edu/~jiasi/teaching/cs204_spring16/ 1 Overview Basics Routing algorithms Flooding Spanning trees RPB TRPB RPM Implementations of
Jiasi Chen Lectures: MWF 12:10-1pm in WCH 139 http://www.cs.ucr.edu/~jiasi/teaching/cs204_spring16/
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same content
unicast do?
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Multicast source Multicast destination User not part of multicast group
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Multicast source Multicast destination User not part of multicast group
subscribed to
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Unique part of MAC address 224.10.8.5 May not be unique
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How do hosts talk to routers?
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Router
“Which groups are you part of?” Each client: “I am part of group g”
timer T
g
g
g expires, send my report
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Source-based trees Shared tree What kind of distribution tree? Flood-and-prune Core-based tree Who is part of my multicast group?
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How to route the packets?
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Benefits
Disadvantages
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Advantages
Disadvantages
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a) If received packet on my shortest path to source b) to all “downstream” routers c) to hosts on your subnet Benefits
construct a new tree for each source
Disadvantages
connected to multicast groups
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to source
a) If received packet on my shortest path to source b) to all “downstream” routers c) to hosts on your subnet if they are part of the multicast group
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prune prune prune Benefits
and between routers Disadvantages
routers
a) If received packet on my shortest path to source b) to all “downstream” routers c) to hosts on your subnet if they are part
d) If a “prune” message hasn’t been received
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Link state based
source and set of destinations
information Disadvantage
shortest path if user joins/leaves
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Distance-vector based
to neighbors
cost = infinity to upstream router prune prune prune
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p = prune message sent/received
explicitly remove
join
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Rendezvous point Center-based tree
Source
Receiver
RP
Algorithm Flood-and-prune or center- based? Source-based or shared tree? Flooding/spanningtree Flood Shared RPB Flood Source RPM Flood-and-prune Source DVMRP Flood-and-prune Source PIM-Dense Flood-and-prune Source PIM-Sparse Center-based Mostly shared, can be source
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Source-based trees Shared tree What kind of distribution tree? Flood-and-prune Core-based tree Who is part of the multicast group?
Q: how to connect “islands” of multicast routers in a “sea” of unicast routers?
v mcast datagram encapsulated inside “normal” (non-
multicast-addressed) datagram
v normal IP datagram sent thru “tunnel” via regular IP unicast
to receiving mcast router (recall IPv6 inside IPv4 tunneling)
v receiving mcast router unencapsulates to get mcast
datagram
physical topology logical topology
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Unicast Network multicast End system multicast
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Zhang, SIGMETRICS, 2000.
Maufer
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