m-hbh efficient mobility management in multicast

M-HBHM-HBHEfficient Mobility Management in MulticastEfficient Mobility Management in Multicast

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

NGC ‘02, October 23-25, Boston, MANGC ‘02, October 23-25, Boston, MA

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OutlineOutline

The mobility problem in a multicast group Traditional solutions

Bi-directional tunneling Remote subscription

The original HBH protocol Mobility handling in M-HBH Performance analysis Conclusion

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The problemThe problem

More and more emerging mobile devices Mobility handling became an important service

requirement The multicast service:

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 tunnel convergence (receiver mobility)

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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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Hybrid solutionsHybrid solutions

Switch between the two techniques, based on specific criteria

Mobile Multicast Protocol (MoM) [Harrison et al., Mobicom ’97]

Range-Based MoM [Lin et al., Infocom ’00]

Hierarchical Multicast Architecture [Wang et al., ACM Mobile Networks and

Applications, 2001]

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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

H1

H5

H4

H2

H3

S

r4r3

r2

r1

r4r3S

H4S H3

S H2

H2S

r2

r2r1S

S

MFT

MFT

MFTMFT

MCT

MCT

H1

H2

Relay Node

Branching Node

MFT – Multicast Forwarding Table

MCT – Multicast Control 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

H1

H5

H4

H2

H3

S

r4r3

r2

r1

r4r3

H4S/S H3

H2

H2

r2

r2r1

MFT

MFT

MFTMFT

MCT

MCT

S’

U1

U2

S/S

S/S

S/S

S/S

S/SH2

MFTS/S’

S/S’

S/S’S/S’

S/S’

U Unicast Router

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Receiver mobility with M-HBHReceiver mobility with M-HBH

H1 H2

U

S

r3

r2’r2

r1

r3H1S

S

MFT

MCT

H3

H4r2

SMCT

r2

SMFT

r1 r2r2/r2’ SMCT

r3

Join (r2/r2’)

Multicast Data

HA

HA Home Agent

r2

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Advantages of M-HBHAdvantages of M-HBH

Reduces triangular routingBetter delivery path

No encapsulation, no tunneling Transparent handling of mobility Preserves the advantages of HBH

Passes through unicast-only cloudsTakes into account asymmetric routes,

data is forwarded on direct shortest path

Limits tree reconstruction …

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The M-HBH tradeoffThe M-HBH tradeoff

M-HBH represents a trade-off between:Shortest path deliveryTree reconstruction

M-HBH shortcuts routing triangles, but…Passing through the first (or the last)

branching node does not assure shortest path delivery

Periodical tree reconfiguration can be considered

Reconfiguration frequency is limited

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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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Performance analysisPerformance analysis

Mathematical modelsK-ary treesSelf-similar trees

SimulationRealistic Internet-like generated

topology

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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, for M-

HBH over BT, 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, for M-

HBH over BT, 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