[Mobopts] Re: [Mip6] Delay Analysis for Handoffs with Mobile IPv6 Route Optimization

Hi Thomas.

> I perfectly agree with your characterisation. I did'nt mean to say

Yes, in particular with respect to the reliability of movement predictions, which you are considering in [1]. This is definitely an interesting issue, albeit it is the link-layer folks that must eventually solve it.

I would also assume that the reliability of predictions strongly depends on the access technology. E.g., in GSM, you have bidirectional measurements that you can take into account. This is not necessarily true for other link layers, such as IEEE 802.11.

 > It may as well happen that the degree of coincidence required by your
 >  scheme corresponds to a quite narrow regime in phase space, which is
 >  hardly ever met.

Zero handoff delay, at the IP layer, is indeed possible only when certain assumptions hold. And as discussed in section 7.1 of [2], this is not always the case. However, end-to-end proactivity can perform better than reactive approaches even when conditions are sub-optimal.

To exemplify this, let's consider the packet-propagation latencies on the old path versus the new path during a proactively managed handoff: If the new path is longer, the mobile node may have to wait for packets after it has switched links (subsequent to receiving a Binding Acknowledgment on the old link). If the new path is shorter, some packets may already be lost on the new link before the mobile node arrives there. But in both cases, the blackout time is usually shorter than in a pure reactive approach.

Anyway, all this is discussed in more detail in [2].

• Christian

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[1]
http://www.informatik.haw-hamburg.de/~schmidt/papers/telesys05.pdf [2]
http://doc.tm.uka.de/2006/vogt-2006-delay-analysis-for-reactive-and-proactive-handoffs.pdf

-- 
Christian Vogt, Institute of Telematics, Universitaet Karlsruhe (TH)
www.tm.uka.de/~chvogt/pubkey/


Thomas C Schmidt wrote:

> Hi Christian,


>> While your results [1] on FMIPv6 and HMIPv6 shed light on the 
>> performance of proactivity in combination with local mobility 
>> optimizations and are as such undoubtedly very important, I do not 
>> necessarily consent with your statement that those results can be 
>> conveyed to the end-to-end mobility management that we have been 
>> analyzing [2].
>> 

> 

> I perfectly agree with your characterisation. I did'nt mean to say


>> [1]
>> 
http://www.informatik.haw-hamburg.de/~schmidt/papers/telesys05.pdf 
>> [2] 
>> 
http://doc.tm.uka.de/2006/vogt-2006-delay-analysis-for-reactive-and-proactive-handoffs.pdf



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