Some Context Transfer CT Issues

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Some Context Transfer (CT) Issues

• Rajeev Koodli and Charles E. Perkins

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Topics

• CT - Handover inter-working
• CT Transport considerations

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Handover - CT

• IP handover
• a process which enables a MN to acquire
  network layer connectivity when it changes its
  access routers, allowing it to send and receive
  IP packets
• IP handover is a routing issue
• Context Transfer
• a process which facilitates continued offering
  of IP features, typically during terminal
  mobility
• CT addresses performance of transport protocols
  (TCP/RTP)
• assuming IP connectivity is available

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How should handover and CT inter-work ?

• The purpose of CT is to enhance handovers by
  transferring feature state associated with packet
  forwarding
• Handover controls the epoch when packet
  forwarding path changes
• So, shouldnt the transfer of context associated
  with packet forwarding be synchronized with
  handover ?
• However, CT must not depend on any particular
  handover protocol

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Is handover complete without CT ?

• If No
• we are re-defining handovers or defining CT
  handovers since existing handovers can complete
  without CT
• an existing handover protocol may not work with
  CT
• If Yes
• concerns regarding seamlessness, e.g., how does
  the new-AR handle a compressed packet from the MN
  if context is absent ?
• however, timely presence of context is a CT
  performance issue perhaps not a reason to
  re-define handovers
• besides, each feature must know how to
  re-initialize

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Transport Considerations

• CT encompasses diverse set of features each with
  disparate transport (latency, reliability)
  requirements
• CT is also anticipated to be useful in handovers,
  ad hoc networks, paging etc
• Therefore, it is best to use the simplest
  available form of transport

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Proposal

• Start defining inter-operable contexts for a
  variety of feature contexts
• Carry the standard feature contexts along-with
  handover messages and demonstrate feasibility
• Facilitate CT for different target applications
  including handovers, paging etc.

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CT framework
Target AR Selection Process
R1
R2
CT
Handover Process