Protocol Design for Scalable and
Adaptive Multicast for Group
Communication
De-Nian Yang and Wanjiun Liao
ICNP'08
Presented by Lei Sun
Background & Motivation 1/3
Multicast communications
IP Multicast
Each router need to store a forwarding state for each
multicast group.
Explicit Multi-Unicast (Xcast)
Addresses of the multicast tree are included in the
header of multicast packet data.
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Background & Motivation 2/3
Adaptations
IP multicast
Not scalable in term of the number of group
considering routers’ memory.
Xcast
Not scalable in term of the group size considering the
delay.
Problems
Network may suffer scalability problems if end users
choose the improper Multicast communication method.
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Background & Motivation 3/3
Scalable and adaptive protocol
Scalable both in terms of group size and group
number
Optimal solution
Routers with forwarding states can be either
branching or non-branching
Adaptive to the dynamic group members
Extendable in existing tree
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Design
REMOVE & MOVE
Minimize the number of router which store the
forwarding states.
States & Messages
Support dynamic group membership and
rerouting of multicast trees when the network
topology is changed.
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Protocol operations (1/4)
States
Group ID (IP addresses)
Maximum number of addresses in each Xcast packets
Join timers
Move_Up timer
Addresses of parent node and upstream state node
Addresses of downstream state nodes
Move_Down timer
messages
Join
Leave
Inform_Up_note
Move_Up
Move_down
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Protocol operations (2/4)
(a) Node 8 joins the multicast tree.
(b) Node 2 finds that the forwarding
state of node 4 can be removed.
(c) The forwarding state of node 4 is removed.
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Protocol operations (3/4)
(d) Node 7 creates a forwarding state
at node 4.
(e) The forwarding entry of node 7 is
moved to node 4.
(f) After the network topology
changes, node 1 is the new upstream
state node of node 11.
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Protocol operations (4/4)
(g) Since node 1 has three
downstream state nodes from
the interface to node 3, it creates
the forwarding state at node 3.
(h) The forwarding state of node 1 from the
interface to node 3 is moved to node 3.
(i) After the forwarding state of
node 4 is removed, the
assignment of the state nodes
is optimal.
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Simulation Results (1/2)
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Simulation Results (2/2)
Fig. 3. Average
number of state
nodes in a
multicast tree in
different graphs
with different δ
and different
group sizes.
Fig. 4. Protocol
overheads in
different networks
with different δ
and different
group sizes.
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Conclusion
Unprofessional writing
Bad organized
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