multicasting
DESCRIPTION
Multicasting. Jean Walrand EECS. Outline. Definitions Broadcast, Multicast, Anycast Examples ARP, ICMP, Group Flooding Routing Multicast Tree of shortest paths; shortest tree Multicast Backbone Overlay Join Groups Soft State Reliable Multicast Nacks, Aggregation - PowerPoint PPT PresentationTRANSCRIPT
UCBMulticasting
Jean WalrandEECS
UCB Outline Definitions
Broadcast, Multicast, Anycast Examples
ARP, ICMP, Group Flooding Routing Multicast
Tree of shortest paths; shortest tree Multicast Backbone
Overlay Join Groups Soft State
Reliable Multicast Nacks, Aggregation
Multilayer Multicast
UCB Definitions
Broadcast One to all
Multicast One to all members of a group
Anycast One to any member of a group
UCB Examples
ARP: Broadcast to LAN (Note: VLANs) 11…11 = “broadcast” address on Ethernet
ICMP: Routers broadcast their link states in OSPF
Group: Multicast of seminar to “subscribers” Class-D IP addresses = group addresses
UCB Flooding
Send on all other ports: Remember seen packets, or Mark route on packets
B C
A
[1][1]
{1}{1}
[1] [1]
B C
A
[1]
[1; A] [1; A]
[1; A, C][1; A, B]
UCB Routing Multicast
Simplest: Tree of shortest paths Example
2
1
2
2
2
1
1
1
1
S
D1
D2
UCB Routing Multicast (continued)
Optimal: Shortest tree Example
2
1
2
2
2
1
1
1
1
S
D1
D2
UCB Routing Multicast (continued)
Comparison:
2
1
2
2
2
1
1
1
1
S
D1
D2
2
1
2
2
2
1
1
1
1
S
D1
D2
Tree of shortest paths Sum of lengths = 9
Shortest tree Sum of lengths = 8
UCB Routing Multicast (continued)
RPB: Reverse Path BroadcastRouter R sends packet received from A if A is
on the shortest path from R to S.
2
1
2
2
2
1
1
1
1
S
D1
D2
RLink ARA
UCB Routing Multicast (continued)
RPM: Reverse Path MulticastRPB + Prune back if no member of Mcast
group
2
1
2
2
2
1
1
1
1
S
D1
D2
PRLink RP
G
Not G
PrunePrunePrune
UCB
Join G
G
Routing Multicast (continued)
PIM-Dense Mode RPR + Prune + Graft (+ periodic RPR + Prune)
2
1
2
2
2
1
1
1
1
S
D1
D2
PrunePrune
GraftGraftGraft
UCB Routing Multicast (continued)
PIM-Sparse ModePeriodic Join/Prune Messages from DR to RPAssumption: Relatively few group members
UCB Reliable Multicast (continued)
ACKs do not scale NACKs may implode => NACK aggregation
1 11 1 1
1 1
UCB Reliable Multicast (continued)
ACKs do not scale NACKs may implode => NACK aggregation
2 2
2 2
UCB Reliable Multicast (continued)
ACKs do not scale NACKs may implode => NACK aggregation
3 33 3 3
3 3
NACK2
[Remember for T seconds]
UCB Reliable Multicast (continued)
Other idea: Designated Receivers
NACK n
[n]
Source
DR DR
UCB Multilayer Multicast Different channel bandwidths => Multiple Layers
SourceLayer 1
Layer 2
Random “join” experiments