Mobile IP: Multicast Service

1
Mobile IP Multicast Service

• Reference Multicast routing protocol in mobile
  networks Hee-Sook Shin Young-Joo Suh, Proc.
  IEEE International Conference on Communications
  (ICC), 2000 pp. 1416 -1420 (MobileIPMulticast-1.p
  df)

Reference Multicast routing by mobility
prediction for mobile hosts Young-Joo Suh
Dong-Hee Kwon, and Woo-Jae Kim, Proc. IEEE ICC,
2003 pp. 865 -869 (MobileIPMulticast-7.pdf)
2
Related Work

• Foreign agent-based multicast
• Remote subscription
• A mobile host has to subscribe to multicast
  groups whenever it moves to a foreign net.
• Simple, not required any encapsulations
• Offering an optimal routing path
• Non-existence of duplicated packets
• Mobility ? expensive multicast service
• Extra delay incurred from rebuilding a multicast
  tree can create the possibility of a disruption
  in multicast data delivery

3
Related Work (cont)

• Home agent-based multicast
• Bi-directional tunneling
• Data delivery is achieved by unicast Mobile IP
  tunnleing via the home agent
• When the HA receives a multicast packet destined
  for a mobile host, it encapsulates the packet
  twice (with 1. the mobile host address and 2. the
  care-of-address of the mobile host) and then
  transmits the packet to the mobile host as a
  unicast packet
• If multiple mobile hosts that belong to the same
  home network visit the same foreign network,
  duplicate copies of multicast packets will arrive
  at the foreign network (see the figure on next
  slide)

4
Multicast data duplication problem in HA-based
multicast
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Related Work (cont)

• MoM (Mobile Multicast)- Ref.8 ACM MOBICOM97
• Improve home agent-based multicast protocol
• A HA forwards only one copy of the multicast
  packet to each foreign network that contains its
  mobile hosts
• Upon receiving the multicast packet, a FA
  delivers it to mobile hosts using link-level
  multicasting
• Tunnel convergence problem

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Tunnel convergence problem
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Tunnel convergence problem

• Solution
• The FA appoints one HA as the DMSP (Designated
  Multicast Service Provider) for the given
  multicast group
• The DMSP forwards only one packet into the
  tunnel, while other HAs that are not the DMSP do
  not forward the packet
• Drawback multicast packets from both the DMSP
  and a multicast router can cause a duplication
  since it is possible that local static hosts in
  the foreign network are members of the same group
  as the visiting mobile hosts (see the figure on
  next slide)

8
Duplication problem for DMSP scheme
9
Non-optimal delivery route for DMSP scheme
10
Proposed Protocol

• MMA (Multicast by Multicast Agent)
• Multicast Agent (MA), Multicast Forwarder (MF)
• MAs provide multicast service to mobile hosts
• Each MA has one MF per multicast group and the MF
  of an MA is the MA that forwards multicast
  packets to it
• The MF of an MA may be the MA itself when its
  local network is included in the multicast tree
• Or the MF can be an MA in another network that
  belongs to the multicast group

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Proposed Protocol (cont)

• Example
• A mobile host moves from N1 to N2
• 1. The mobile host send its MF information to the
  MA in N2 during registration, which is used by
  the MA for selecting the new MF
• 2. If N2 belongs to the multicast delivery tree,
  the MA itself becomes the MF
• 3. If the MA in N2 does not belong to the
  multicast delivery tree, the MF value that the
  mobile host had in N1 is used as the MF in N2
• 4. Optionally, the MA in N2 selects one that is
  closer to it, between the MF information that the
  MA had and the MF that the mobile host had in N1

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Proposed Protocol (cont)
13
Proposed Protocol data structure
14
Algorithm when a MH arrives
15
Algorithm when a multicast datagram arrives
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Algorithm when a MH (member) leaves the current
network
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Algorithm a control packet from another MA
arrives
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Discussion

• The proposed MMA protocol offers better
  (sub-optimal) delivery route than HA-based
  protocols since the MF is generally located in an
  adjacent network that is included in the
  multicast delivery tree
• The MMA protocol reduces the number of duplicated
  packets and total amount of tunneling since
  multicast packets can be forwarded directly from
  the multicast router in the current network

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Performance Evaluation

• Compare MMA, MoM, HA-based protocol
• Criteria
• Amount of multicast data traffic
• Traffic on the multicast tree traffic occurred
  by tunneling from MF to the mobile host
• Average delivery path length
• Scalability with multicast group size
• Comparison of DMSP handoff with MF handoff

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Simulation Parameters
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Discussion- Tunneling

• The number of tunneling is proportional to
• 1. The number of mobile hosts in the HA-based
  multicast protocol
• 2. The number of foreign networks which has
  mobile hosts having multicast membership in the
  MoM protocol
• 3. The number of MAs which receive data forwarded
  by an MF (for MMA protocol)
• See the figure on next slide

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Simulation result- Fig. 8
of tunneling

• T 50, MR3

23
Simulation result- Fig. 9
MoM sparse
MMA sparse
Optimal

• MMA shows an improved performance and the
  difference becomes larger for large tree sizes

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Simulation result- Fig. 10

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Discussion- Fig. 10

• MoM shows shorter tree path length than MMA, but
  MoM shows much more tunnel path length than MMA
• As a result, MMA shows less total path length
  than MoM

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Simulation result- Handoff
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Discussion- Fig. 11

• MF handoff frequency in MMA is much less than
  DMSP handoff frequency
• Problem of frequent DMSP handoff
• Cause much traffic in network
• Increase network overhead
• Cause performance degradation due to the out-of
  service period during handoff

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Extended work (ICC2003)

• Remote-subscription vs. MA-based Tunneling
• Allow necessary join operations
• Reduce packet delivery length
• Minimize the number of unnecessary join
• Necessary join
• Only when the mobile host is expected to remain
  in the network relatively long period of time
• Staying time at the previous network(s)
• Threshold value for join

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Extended work (example)
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Host Mobility Prediction

• Speed GPS (not always available)
• Expected staying time

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Simulation Network Model
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Simulation Parameters
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Simulation result Fig. 3
of tunneling
MMA with join option
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Simulation result Fig. 4
35
Simulation result Fig. 5
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Simulation result Fig. 6a
of MAs that currently have no visiting MHs
subscribing multicast groups that MAs join for
the MHs