RE: [DNA] Definition of "Link Up" and "Link Down" events?

[NJEDJOU Eric RD-RESA-REN <eric.njedjou@francetelecom.com>]

I have a little problem with the most recent defintion (Bernard's) of Link-Down suggested. The statement "A Link Down event is only generated once the link layer considers the link unusable" looks (to me at least) a bit contradictory to the first sentence of the definition in the sense that the link layer can consider the link unusable even without any change having occured in the link state machine: PDP context activated in GPRS/UMTS but very high BER  
Said differently, the definition implies that the event cause can be "state changed" in the link layer state machine as well "state did not changed" (as the link can become unusable within the same state) which is a problem.

Hope my concern is understood.

Insn't 
"An event provided by the link layer that signifies a state change associated with the interface no longer being capable of communicating IP packets. transient periods of high frame loss are not sufficient." enough for Link down definition?

Please advice

Eric Njedjou

-----Message d'origine-----
De : owner-dna@ecselists.eng.monash.edu.au [mailto:owner-dna@ecselists.eng.monash.edu.au] De la part de Bernard Aboba
Envoyé : samedi 28 mai 2005 22:58
À : dna@eng.monash.edu.au
Objet : Re: [DNA] Definition of "Link Up" and "Link Down" events?

Erik Nordmark wisely observed:

> I think it would be good if the definitions would clarify that even if 
> the link layer on the host sees 100% packet loss for a short while, it 
> doesn't necessarily imply that a link down event should be generated.
> (It presumably shouldn't be generated until the link layer abandons 
> the
> L2 association/connection/whatever.)

How about this?

Link Down
An event provided by the link layer that signifies a state change associated with the interface no longer being capable of communicating IP packets. A Link Down event is only generated once the link layer considers the link unusable; transient periods of high frame loss are not sufficient.

Link Up
An event provided by the link layer that signifies a state change associated with the interface becoming capable of communicating IP packets.