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Mobility and MulticastMobility and Multicast Protocol Design and AnalysisProtocol Design and Analysis
Rolland Vida, Luis Costa, Serge FdidaRolland Vida, Luis Costa, Serge FdidaLaboratoire d’Informatique de Paris 6 – LIP6 Laboratoire d’Informatique de Paris 6 – LIP6
Université Pierre et Marie Curie, ParisUniversité Pierre et Marie Curie, Paris
ISCIS XVII, October 28-30, Orlando, FLISCIS XVII, October 28-30, Orlando, FL
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 22
OutlineOutline
The mobility problem in a multicast group Traditional solutions
Bi-directional tunnelingRemote subscription
Reducing routing triangles in M-HBH Performance analysis
Theoretical modelsSimulation results
Conclusion
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 33
The problemThe problem
More and more emerging mobile devices Mobility handling became an important service
requirement Consider the following:
a multicast group, identified by a multicast address G
a source S that sends data to G a receiver r that listens to packets sent to G
How to assure multicast data delivery if … the source S is mobile
or the receiver r is mobile
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 44
Traditional solutions (1)Traditional solutions (1)
Proposed by Mobile IP [Perkins, RFC 3220] Bi-directional tunneling (BT)
tunnel between the home and the foreign location of the MN
Source mobility: data is tunneled to the home network, and then retransmitted on the old tree
Receiver mobility: data is delivered on the old tree, and then tunneled to the MN
Drawbacks: triangular routing encapsulation/decapsulation of data
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 55
ExampleExample
R1
R5
R4
R2
R3
S
r4r3
r2
r1
S’ HA
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 66
Traditional solutions (2)Traditional solutions (2) Remote subscription (RS)
reconfiguration of the multicast tree according to the new location of the MN
Source mobility: receivers redirect their Join messages towards the new location of the source
Receiver mobility: the MN joins the tree from its new location
Drawbacks: Source mobility:
• the entire tree must be reconstructed• reconstruction is costly, not efficient for a highly
mobile source Receiver Mobility
• cost is lower, only a branch has to be added
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 77
ExampleExample
R1
R5
R4
R2
R3
S
r4r3
r2
r1
S’
R6
R7
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 88
ExampleExample
R1
R5
R4
R2
R3
S
r4r3
r2
r1
S’
R6
R7
R1
S
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 99
HBH multicast HBH multicast
In traditional multicast, the group is a single unit, identified by the multicast address
Mobility of an individual member is hard to handle Keep the unit (tree) + tunnel Reconstruct the unit (tree)
HBH – Hop-By-Hop Multicast Routing [Costa et al., Sigcomm ’01] Uses a recursive unicast addressing scheme to
provide multicast Data is not sent to the group, but to the next
branching node Nodes are handled as individuals, not as a
group
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1010
Data delivery in HBHData delivery in HBH
U
U
H3
H1
H2
S
r4r3
r2
r1
r4r3
H3H2
H1
r2r1
MFT
MFT
MFTMFT
U
H2
Unicast Node
HBH Branching Node
MFT – Multicast Forwarding Table
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1111
The M-HBH protocol The M-HBH protocol
In HBH multicast, nodes are treated as individuals, not as a group
Mobility is easier to handle Mobile Hop-By-Hop Multicast Routing
Protocol Extension of HBH Handles both source and receiver
mobility Mobile Node
Multicast connectivity – M-HBHUnicast connectivity – Mobile IP
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1212
Source mobility with M-HBHSource mobility with M-HBH
U
U
H3
H1
H2
S
r4r3
r2
r1
r4r3
H3H2
H1
r2r1
MFT
MFT
MFTMFT
S’
U
U
H1
MFT
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1313
Receiver mobility with M-HBHReceiver mobility with M-HBH
H1 U
U
S
r3
r2’r2
r1
r3H1
MFT
U
U
MFTr1 r2r2’
Join (r2/r2’)Multicast Data
HA
HA Home Agent
r2
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1414
Routing triangleRouting triangle
SS’
F
xS
yS
zS
S
L
z r
y r
x r
F First branching node
L Last branching node
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1515
Perfect K-ary tree of depth D Receivers randomly placed on leaves is obtained as a weighted
average:
where is the probability of the first branching node being hops away from the source
Theoretical modelsTheoretical models
1
0
( )D
S Sj
X jP X j
( )SP X j
j
SX
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1616
Self-similar k-ary tree of depth D Between a node at level and a
node at level there are concatenated links, and
where is the similarity factor Then, is obtained as follows:
Theoretical models (2)Theoretical models (2)
l1l
lt
1 , 1l lt t
SX1
1
1 ( )1
jDD j
S Sj
X P X j
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1717
ExampleExample
Level 3
Level 2
Level 1
Level 0
Self-similar tree with k = 2, D = 3, and = 2
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1818
Simulation results (multicast Simulation results (multicast tree shape)tree shape) Average length of Xs vs. Xr
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 1919
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 2020
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 2121
Simulation results (source Simulation results (source mobility)mobility) A) Average delivery delay M-HBH vs. BT
vs. RS B) Relative gains in average delivery
delay proportional to the average length of Xs
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 2222
Simulation results (receiver Simulation results (receiver mobility)mobility) A) Average delivery delay M-HBH vs. BT
vs. RS B) Relative gains in average delivery
delay proportional to the average length of Xr
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 2323
ConclusionConclusion
Traditional solutions have drawbacks: Triangular routing, encapsulation (BT) Frequent tree reconstruction (RS)
M-HBH uses a recursive unicast addressing scheme Reduces routing triangles eliminates tunneling limits tree reconstruction
Simple, transparent, incrementally deployable Simulations show important performance gains Further details and analysis:
hhtp://www-rp.lip6.fr/~vida/mhbh_techrep.pdf
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 2424
Questions?
ISCIS XVIIISCIS XVII, , Orlando, FLOrlando, FL 2525
Mobile multicast sourceMobile multicast source Shared Multicast Tree (CBT, PIM-SM)
S sends data in unicast to the core (RP) data is retransmitted on the shared tree if S moves in a new network, it still can send
unicast packets to the core (RP). Data is delivered to receivers.
Source-Specific Multicast Tree (PIM-SSM) the multicast tree is rooted in the home
network of S S moves in a new network and obtains a new
address (S’): Multicast packets sent by S’ are dropped if …
• no multicast router in the visited network• no multicast routing state in the router