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

[Bernard Aboba <aboba@internaut.com>]

>    Node's establishment of a link-layer connection with an attachment
>    point that signifies the availability of IP service (i.e., being able
>    to send and receive IP packets) between the two is considered a link
>    up event.

Does this preclude "Link Up" from being sent on a uni-directional link?
In other words, must the link layer demonstrate bi-directional
reachability prior to sending a "Link Up" event?

>    Link down event signifies the discontinuation of the IP service
>    between the node and the attachment point.  When the link-layer
>    connection is physically or logically torn down and it can no longer
>    carry IP packets, this is considered to be a link down event.

This seems compatible with existing usage and some of the previous
discussion.

> > Or can a "Link Up" event occur when a STA wanders out of range of an
> > access point, retransmits packets multiple times without a response,
> > scans, and then returns within range of the same AP, all without
> > changing state within the link layer state machine?  In this scenario,
> > is a "Link Down" event also sent?
>
> I don't think so.

I would agree.

> Eventually a continued "low quality" may lead to the L2 deciding a state
> change that leads to a "link down", but this is a L2 design and
> implementation decision.

Agree that the operative term is "eventually" (e.g. link layer state
transition).