Subject: RE: Current Movement Detection Process and Time (Re: [mobile-ip] Re: closing issue #297 (erik's and steven's technical comments on base))

From: [email-masked]
Date: Wed, 30 Apr 2003 16:38:50 -0500

>> >The only thing I feel uneasy about is that, because of lack of detail,
>> >people may implement MN to send excessive RS or NS message
>> >to overflow network.
>>
>> I think RS should not be the preferred method for probing anyway. NS
>> is preferred.
>> So would it be sufficient to have text that highlights the problem of
>> probing based on RS/NS and recommend the use of L2/L3 indications
>> while leaving any details of these out.
>>
>
>I'm not clear that the direction in this choice is so clear cut. 

Would you agree that NS is less expensive than RS for the probing
operation? In some earlier discussions (not on list) we concluded this
to be the case.

>I'd
>prefer something more general, to say that a node should minimize
>traffic involved in MD probing. I think it is still an open question
>exactly how this should be done, something for the new MD WG.

No question that details of MD need to be worked out separately and
there is no point in speculating what WG etc., when none exist yet. 

But in order to close the current issue for the base spec, I think the
minimalist approach of providing some guidelines for probing and
leaving the larger part for implementations should be
sufficient. Additionally a warning about causing excessive traffic on
the link as a result of unwarranted probing should be highlighted.

>            jak

-Basavaraj

---

From: "James Kempf" <[email-masked]>
Date: Wed, 30 Apr 2003 15:26:28 -0700

> operation? In some earlier discussions (not on list) we concluded
this

That is why I said it was not clear to me. On the one hand, use of NUD
as specified in RFC 2461 will likely not be better, due to the
problems Erik outlined. On the other, as Vijay has mentioned, RSs have
lots of timers, so without a simplified RS algorithm it may make
implementations substantially more complex. Maybe a simple probe would
work, but after having studied the issue of movement detection and
handover now for a while, I've learned that algorithms which look
quite straightforward after some amount of design discussion in
mailing list traffic and Internet draft text often turn out to have
hidden complexities that make them poor choices after they are
implemented and tested. This is why I would prefer to err on the side
of caution, and only specify what we know works ("running code" and
further: "tested running code").

> the link as a result of unwarranted probing should be highlighted.

I'm comfortable with guidelines, what I'd advise against is saying
"here's a protocol for probing". Jari's proposed solution, with Erik's
modification, sounded fine.

            jak