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
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