Re: Revised terms

[huitema@bellcore.com (Christian Huitema)]

On Jul 25, 12:25pm, Steve Deering wrote:
> Subject: Re: Revised terms
> Folks who have no patience for terminological nit-picking should skip
> this message now (assuming they haven't already filtered out this
thread).

Yeah, right..

> > BDL	Bidirectional link. A link layer where transitive communcation
> > 	occurs.
> >
> > UDL	Unidirectional Link. A link layer where non-transitive
communication
> > 	occurs or BDL behaviour is not permitted.
> >
> > UDLN	Unidirectional Link Network. A network composed of or
containing UDLs.
>
> A link and a network are one and the same thing, in IP terminology (or
at
> least in IPv6 terminology, where we are trying to be a bit more
rigorous).

I was going to make the same comment, then read Steve's message.  Well,
from a routing point of view, the important point is transitivity, and the
assumption that if A hears B, then B will hear A.  This used to be true in
most copper and fiber based links, is kind of dubious in wireless links
and is definitely not guaranteed with satellites.  So, I would opine that
what we are dealing with are "Non Transitive Links" (NTL) where the
transitivity is not guaranteed.

In earlier discussions, we shied away from general wireless links. In
UDLR, we concentrated in links where:

* there is no guaranties that if B hears A, A will hear B.

* there is definitely an expectation that if B and C are "connected" to
the link and B hears A, then C also hears A.

The second proposal is not true in general wireless networks, and leads to
the distinction between "senders", "receivers" and "sender receivers".
 This distinction actually applies to the station's interface to the NTL,
which can an NTR, an NTS or an NTB...

-- 
Christian Huitema