Analysis of IPv6 Relocation Delays

Analysis of IPv6 Relocation Delays
draft-vogt-dna-relocation-01.txt
Christian Vogt, Roland Bless, Mark Doll, Gregory Daley
[email protected], [email protected], [email protected],
[email protected]
Problem Statement, Proposed Solutions, Discussion
63th Meeting of the Internet Engineering Task Force
DNA Working Group Session, August 4, 2005
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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What are We Looking at?
When a mobile node undergoes L2 handover…
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Mobile node determines whether it changed IP attachment
This involves router discovery
Mobile node configures new addresses in case IP attachment changed
This should be fast
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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How This Should Look Like
Access Router
Local Link
Mobile Node
L2 Handover
Make LL addr. optimist.
Rtr Sol (TSLLAO)
Rtr Adv
IP re-attachment!
New optimist. global addr.
Home Agent
Correspondent Node
MIPv6 Binding Update
Ngb Sol (ODAD)
…
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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So What's the Problem?
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Optimistic addresses require prior transmission of an NS
Sending NS requires prior transmission of an MLD Report
MLD Report "SHOULD" be randomly delayed by up to 1 second
when sent during interface initialization [RFC 2461/62 bis]
Objective of delays: de-synchronize simultaneous boot-up of multiple
hosts
But: prevents fast IP re-attachment (and detection of it)
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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How It Really Looks Like
Access Router
Local Link
Mobile Node
L2 Handover
Make LL addr. optimist.
De-synchronization
delay (0..1000ms)
MLD Report
Ngb Sol (ODAD)
Rtr Sol (TSLLAO)
Rtr Adv
IP re-attachment!
New optimist. global addr.
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
Home Agent
Correspondent Node
MIPv6 Binding Update
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Proposed Solutions
Omit delay for initial MLD Report upon movement
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De-synchronization delay is tailored to stationary scenarios
Mobility introduces inherent "natural" de-synchronization
Omit delay when mobile node receives L2 trigger indicating that an
interface, which was operational, went down and came up again
Start using optimistic addresses before initial NS
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No technical reason why initial NS must be sent first
Adding Robustness: Retransmit MLD Report and NSs
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Both MLD and ODAD are unreliable since messages may get lost
Multiple MLD Reports and NSs increase robustness
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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This is How it Would Look Like
Access Router
Local Link
Mobile Node
Make LL addr. optimist.
L2 Handover
Rtr Sol (TSLLAO)
Rtr Adv
IP re-attachment!
New optimist. global addr.
Home Agent
Correspondent Node
MIPv6 Binding Update
MLD Report
Ngb Sol (ODAD)
…
MLD Report
Ngb Sol (ODAD)
…
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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Conclusions
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Problem statement
ƒ Current IPv6 Autoconfiguration procedures prevent efficient
detection of IP re-attachment due to de-synchronization delays
ƒ One scenario where this is problematic has been shown
ƒ More problematic scenarios in draft-vogt-dna-relocation-01.txt,
with and w/o TSLLAO, with and w/o RS
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Proposed solutions
ƒ Omit delay for MLD Reports upon movement
ƒ Start using optimistic addresses prior to initial NS
(modification to draft-ietf-ipv6-optimistic-dad-05.txt)
ƒ Retransmit MLD Reports and NSs for robustness
Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany
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