Subject: [mobile-ip] MIPv6 Mobile Prefix Solicitation scheduling confusion

From: Ville Nuorvala <[email-masked]>
Date: Mon, 27 Jan 2003 17:05:55 +0200 (EET)

Hi guys,

I just noticed some very strange lines of text in Section 11.4.2 of draft
20:

   The mobile node SHOULD send a Solicitation to the home agent when its
   home address will become invalid within MaxRtrAdvInterval seconds,
   where this value is acquired in a previous Mobile Prefix
   Advertisement from the home agent.  If no such value is known, the
   value MAX_PFX_ADV_DELAY seconds is used instead (see Section 12).

First of all, the MN doesn't get MaxRtrAdvInterval, since MPA:s don't
have the Advertisement Interval Option. Should we allow it in MPA:s?

Second, MAX_PFX_ADV_DELAY isn't specified anywhere in the specification.

Third, if Adverisement Interval Options are allowed, isn't 0.07 seconds
(minimum allowed value for MaxRtrAdvInterval, Section 7.6) a bit small for
this purpose? You can't afford much latency in the network if you need
roundtrip times of less than 0.07 seconds.

How is the MN also supposed to cope with situations where either the MPS
or the MPA gets lost on the way? It will at least not be able to resend
the MPS before the prefix has expired, since INITIAL_SOLICIT_TIMER is
defined as 3 seconds (Section 12).

Ville
--
Ville Nuorvala
Research Assistant, Institute of Digital Communications,
Helsinki University of Technology
email: [email-masked], phone: +358 (0)9 451 5257