Re: RE: AD request / L2 Triggers Chapter Statement

Behcet Sarikaya wrote:
> Hi Scott,
>   I am attaching something that can be used to the
> effect of a charter.
>   Any comments?

Hi, all,

I haven't seen much discussion on this, so I'll start with a few questions:

> ------------------------------------------------------------------------
> 
> L2 Triggers BOF (l2tr)
> 
> July 2002
> ================================
> 
....
> 
> The ability to quickly and efficiently determine the existence (or
> non-existence) of a link is needed most commonly as a consequence of
> movement-induced changes in network topology. Mobile handoff, whether
> in cellular or WLAN contexts, generally requires that the entire
> process complete within 10's of milliseconds is seamless voice
> service is to be maintained. This requires very fast detection of
> changes in link status. Since a link layer best knows its current
> link status it is natural to use L2 triggers for
> this purpose.

The whole of L2 Triggers assumes that:

	1) events occur at the link on the timescale of milliseconds
	2) these events must be communicated to L3
	3) L3 can do something useful with these triggers

#1 is granteed, but #2 assumes that #3 ever occurs. There is little in 
IP as a whole that supports such "realtime" requirements of millisecond 
responses. In fact, that's in opposition to most of the rest of the 
Internet architecture.

I would suggest that a link that has such events is in fact a link built 
on links, e.g., a virtual link layer. There have been others - Sonet, 
ATM, etc., that have had similar millisecond (or faster) handoff 
mechanisms. There may be value in standardizing that sort of link 
facility in general, but can anyone clarify why it is useful to hand 
such urgent information to a layer that is otherwise non-urgent in nature?

I.e., specifically:

	A) justify millisecond event communication to a non-realtime
	layer-3 (what specifically will IP do?)

	B) (alternately) justify that this is not an intralink layer
	(e.g., is it inter-link, between two different links?
	will any one link ever need to tell any other link layer?)

Joe






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