[Mobopts] Re: Review of draft-irtf-mobopts-mpa-framework-00
Ashutosh Dutta <adutta@research.telcordia.com> Wed, 24 October 2007 16:00 UTC
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Date: Wed, 24 Oct 2007 11:59:54 -0400
From: Ashutosh Dutta <adutta@research.telcordia.com>
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To: Christian Vogt <christian.vogt@nomadiclab.com>
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Cc: ktaniuchi@tari.toshiba.com, William Arbaugh <waa@cs.umd.edu>, Mobopts <mobopts@irtf.org>, vfajardo@tari.toshiba.com, Henning Schulzrinne <hgs@cs.columbia.edu>
Subject: [Mobopts] Re: Review of draft-irtf-mobopts-mpa-framework-00
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Christian, Appreciate your careful review of the draft draft-irtf-mobopts-mpa-framework-00. We will take care of these comments and suggestions in the revised version of the draft. Based on Rajeev's email few days back, I also take this opportunity to solicit comments and suggestions from others in the mailing list on this draft. Regards Ashutosh Christian Vogt wrote: > Folks, > > Ashutosh asked me to take a look at > draft-irtf-mobopts-mpa-framework-00, which I am happy to do. > > Draft-irtf-mobopts-mpa-framework-00 specifies a framework for efficient > and secure handovers of mobile hosts between administrative separate > networks. This includes a pre-authentication of the mobile hosts to one > or more candidate networks. The framework is generic in that it is > independent of the authentication mechanism and mobility protocol. > > A strength of this framework is that it is based on security > relationships between a mobile host and different networks, > whereas it does not depend on trust or security > relationships between administrative separate networks. > This is an advantage in terms of deployment scalability, in > particular in a more and more heterogeneous Internet. > > The draft is of good editorial quality. It also describes > related work and clearly explains how it differs from that. > > Below some more specific technical comments: > > - One meta-question I have is why the proactive handover > tunnel connects the mobile host's old point of attachment > with the new access router, and not the mobile host's new > point of attachment with the old access router. In most > cases, this may not make a difference. But if the signal > strength on the old link is fading quickly, it would be > advantageous to have the mobile host connect to the new > point of attachment as early as possible. E.g., F-MIPv6 > follows the latter approach and may hence work better when > the overlap between the old and new point of attachment is > small. > > - Section 1.1 lists end-to-end delay as a performance > requirement and cites ITU-T G.114 (One-Way Transmission > Time). The transmission time is not directly related to > mobility management, however, unless you consider > propagation stretches that arise from tunneling, such as in > case of the proactive handover tunnel. > > - Section 1.1: > >> During a mobile's handover, transient traffic cannot >> reach the mobile and this contributes to the jitter as >> well. > > Transient traffic during a handover is lost, whereas jitter > considers the deviation in inter-arrival times of > successfully delivered packets. So the loss of transient traffic during > a handover does not contribute to jitter. I would rephrase this. > >> According to ETSI TR 101 [ETSI], a normal voice conversation can >> tolerate up to 2% packet loss. > > This value is, to my knowledge, the mean packet loss > probability that can be repaired by loss concealment > techniques. The value hence does not apply to the handover > case, which is special in that the packet loss probability > is 100% for a short period. Total packet loss cannot be > repaired by loss concealment techniques -- although some > techniques /attempt/ to repair it by repeating the last > received voice frame several times with decreasing volume. > > A more appropriate metric than the average packet loss > probability would be the handover delay (i.e., for how long > there is a packet loss of 100%). The handover delay is the time during > which the user does not hear anything. Unfortunately, ITU has to my > knowledge never developed a recommendations on what the maximum handover > delay should be. > > - Figure 1: Connection between access routers misses in > domain B. L2 switch in domain B is not labeled. > > - Section 6.3: Maybe you should add some recommendations on who eagerly > the mobile host should pre-authenticate with different candidate > networks. These recommendations should optimally consider the mobile > host's policies, signaling overhead, and handover robustness. > > This is a valuable contribution. Go ahead and publish once Rajeev and > William give you green light! :-) > > Ciao, > - Christian > > > _______________________________________________ Mobopts mailing list Mobopts@irtf.org https://www1.ietf.org/mailman/listinfo/mobopts
- [Mobopts] Review of draft-irtf-mobopts-mpa-framew… Christian Vogt
- [Mobopts] Re: Review of draft-irtf-mobopts-mpa-fr… Ashutosh Dutta
- [Mobopts] Re: Review of draft-irtf-mobopts-mpa-fr… Ashutosh Dutta