Analysis of IPv6 Relocation Delays draft-vogt-dna-relocation-01.txt - - PowerPoint PPT Presentation

Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany 1

Analysis of IPv6 Relocation Delays draft-vogt-dna-relocation-01.txt

Christian Vogt, Roland Bless, Mark Doll, Gregory Daley chvogt@tm.uka.de, bless@tm.uka.de, doll@tm.uka.de, greg.daley@eng.monash.edu.au

63th Meeting of the Internet Engineering Task Force DNA Working Group Session, August 4, 2005

Problem Statement, Proposed Solutions, Discussion

Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany 2

What are We Looking at? When a mobile node undergoes L2 handover…

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 3

How This Should Look Like

L2 Handover Rtr Sol (TSLLAO) Rtr Adv Mobile Node Home Agent Correspondent Node

Make LL addr. optimist.

Access Router Local Link MIPv6 Binding Update Ngb Sol (ODAD)

IP re-attachment! New optimist. global addr.

…

Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany 4

So What's the Problem?

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 5

How It Really Looks Like

L2 Handover Rtr Sol (TSLLAO) Rtr Adv Mobile Node

Make LL addr. optimist.

Access Router Local Link Ngb Sol (ODAD) MLD Report De-synchronization delay (0..1000ms)

IP re-attachment! New optimist. global addr.

Home Agent Correspondent Node MIPv6 Binding Update

Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany 6

Proposed Solutions Omit delay for initial MLD Report upon movement

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

No technical reason why initial NS must be sent first

Adding Robustness: Retransmit MLD Report and NSs

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 7

This is How it Would Look Like

L2 Handover Rtr Sol (TSLLAO) Rtr Adv Mobile Node … Access Router Local Link Ngb Sol (ODAD) MLD Report Ngb Sol (ODAD) MLD Report …

Make LL addr. optimist. IP re-attachment! New optimist. global addr.

Home Agent Correspondent Node MIPv6 Binding Update

Christian Vogt, Institute of Telematics, University of Karlsruhe, Germany 8

Conclusions

Problem statement

• Current IPv6 Autoconfiguration procedures prevent efficient

detection of IP re-attachment due to de-synchronization delays

• One scenario where this is problematic has been shown
• More problematic scenarios in draft-vogt-dna-relocation-01.txt,

with and w/o TSLLAO, with and w/o RS

Proposed solutions

• Omit delay for MLD Reports upon movement
• Start using optimistic addresses prior to initial NS

(modification to draft-ietf-ipv6-optimistic-dad-05.txt)

• Retransmit MLD Reports and NSs for robustness