Subject: [mobile-ip] [Announce] Link Identifier draft.

From: Brett Pentland <[email-masked]>
Date: Fri, 30 May 2003 17:33:54 +1000

Dear mobile-ip group,

A while ago there was some discussion about using link identifiers to 
aid in movement detection.

We have submitted a new individual draft that describes one possible 
mechanism for using link identifiers in this way.

Basically identifiers are generated randomly and transmitted by access 
routers in a router advertisement option.  The draft describes a way for 
all of the routers on a link to agree on a consistent identifier for 
that link so that mobile nodes can use it to recognise when they have 
actually moved to a new link.

This document has not yet reached the ID WWW site, but is
available at the URL:

http://www.ctie.monash.edu.au/ipv6/draft-pentland-mobileip-linkid-00.txt

We are looking forward to you feedback.

Regards,
Brett.

---

From: "Ed Remmell" <[email-masked]>
Date: Fri, 30 May 2003 09:12:01 -0700

Brett -

Personally, I think this new option is a bad idea, since it gives little
extra payback for an increase both in complexity and administrative support.
I don't understand why the MN needs to be aware of multiple routers when it
is away from home, it can just use a single current default router
advertising a global prefix to configure its primary care-of address. This
is simpler, since it is easier to track reachability (both from the router,
as well as bi-directional reachability) of a single router. When the MN
moves from that router to a different router, it most likely needs to select
a new primary CoA and perform a L3 handover, unless the new router
advertises the same global prefix.

The R-bit option (global scope router address) works perfectly fine in this
case to disambiguate between routers, assuming duplication of link-local
scope addresses if the routers are on different links.

In section 9.1 you say:
"   This document describes a mechanism by which reception of an RA is
   used by nodes to de-configure the current default router (and associ-
   ated on-link addresses associated with this router).  Additionally,
   in many environments, movement detection is used as an instigator for
   configuration signaling."

I'd say in response that whenever the MN switches to a new current default
router when operating away from home, this is likely an indicator that it
has switched to a new link (not always, but it is safe to assume so - note
that MIPL defaults to using eager cell switching for movement detection, and
this algorithm does not work well when there are multiple routers on the
link, so I think for your typical MIPv6 deployment scenario, given the
popularity of embedded Linux, you will only have a single default router on
any given link), in which case it should purge all dynamically discovered
entries (including Neighbor Cache entries, on-link prefixes, etc.) from its
routing tree or the equivalent.

Thanks.
- Ed Remmell
Elmic Systems, USA
http://www.elmic.com

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Brett Pentland
> Sent: Friday, May 30, 2003 12:34 AM
> To: [email-masked]
> Cc: Greg Daley; JinHyeock Choi
> Subject: [mobile-ip] [Announce] Link Identifier draft.
>
>
> Dear mobile-ip group,
>
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