mobility and multicast protocol design and analysis rolland vida, luis costa, serge fdida...

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

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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

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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

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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

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ExampleExample

R1

R5

R4

R2

R3

S

r4r3

r2

r1

S’ HA

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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

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ExampleExample

R1

R5

R4

R2

R3

S

r4r3

r2

r1

S’

R6

R7

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ExampleExample

R1

R5

R4

R2

R3

S

r4r3

r2

r1

S’

R6

R7

R1

S

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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

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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

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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

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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

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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

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Routing triangleRouting triangle

SS’

F

xS

yS

zS

S

L

z r

y r

x r

F First branching node

L Last branching node

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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

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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

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ExampleExample

Level 3

Level 2

Level 1

Level 0

Self-similar tree with k = 2, D = 3, and = 2

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Simulation results (multicast Simulation results (multicast tree shape)tree shape) Average length of Xs vs. Xr

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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

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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

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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

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Questions?

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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