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

[James Kempf <kempf@docomolabs-usa.com>]

Dan,

Then what would you suggest is the appropriate way to phrase this?

        jak


----- Original Message ----- 
From: "Romascanu, Dan (Dan)" <dromasca@avaya.com>
To: "James Kempf" <kempf@docomolabs-usa.com>; "NJEDJOU Eric RD-RESA-REN"
<eric.njedjou@francetelecom.com>; "Bernard Aboba" <aboba@internaut.com>;
<dna@eng.monash.edu.au>
Sent: Wednesday, June 01, 2005 11:51 PM
Subject: RE: [DNA] Definition of "Link Up" and "Link Down" events?


I would like to draw again the attention of the group that IMO the use
of 'IP packets' to define low link layer link Up / link Down events may
not be appropriate. The 'capability of communicating IP packets'  cannot
be detected in some cases by lower link layers state machines .

Regards,

Dan



> -----Original Message-----
> From: owner-dna@ecselists.eng.monash.edu.au
> [mailto:owner-dna@ecselists.eng.monash.edu.au] On Behalf Of
> James Kempf
> Sent: Thursday, June 02, 2005 6:21 AM
> To: NJEDJOU Eric RD-RESA-REN; Bernard Aboba; dna@eng.monash.edu.au
> Subject: Re: [DNA] Definition of "Link Up" and "Link Down" events?
>
> Eric,
>
>
> 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
>
> jak>> I guess I don't understand the problem. The definition
> leaves it
> jak>> up to
> the link layer to decide what "unusable" means. Whether or
> not that involves a state machine change or some other
> consideration is pretty much up to the link layer to decide.
>
>             jak
>
>
>