Hello Joe,
Follow-up inline...
On 1/23/2015 11:44 AM, Joe Touch wrote:
Charlie,
On 1/23/2015 11:25 AM, Charlie Perkins wrote:
Well, that term "reachable" is itself debatable, as discussed in the
document.
It really isn't unless you're being anthropomorphic, and that's not
useful.
I'd like to hear from other people about this...
Nowhere in the draft is there an attempt to be anthropomorphic.
In particular, "detection" is often used without anthropomorphism.
Connectivity is all that matters, and it's either simplex or duplex,
single-point or multipoint, etc.
The "etc." really matters. Even the term "connectivity"
needs modifiers as you have noted.
In fact the ambiguity surrounding "reachability" was a
motivating factor for writing the document. We thought that "detect"
was a term easily understandable by the intended audience, and up
until now it seems that the document is pretty unambiguous using
that term. The document does not suggest that IP "detects" packets.
Is there an effect you cannot state in terms of existing descriptions
of L2 links?
The effects in the draft are stated in terms of existing descriptions
of L2 links. I am not sure I get your point here.
Note that links* always exist, whether they're up or down; having
links whose up/down state varies over time is already part of exstingn
descriptions too.
*"link", to L3, means something that provides communication between
two L2 endpoints. It has nothing to do with how many hops that takes
at L2.
Check.
...
After reviewing PILC, I find that there is not much overlap with our
draft.
If you're expecting the same kind of obscure terminology, there
wouldn't be.
Many terms in common use have been found to be ambiguous, so
unambiguous terminology is then naturally less common. But "obscure"?
Anthropomorphic at best.
Which terms are anthropomorphic?
What you're describing is an unstable set of unidirectional L2 paths,
and you want to call that an L2 network. It isn't.
We very definitely do *not* want to claim it is an L2 network.
Then what is it? A set of L2 networks? Those are interconnected by
what L3 calls routers.
Well, in [manet] we are dealing with routers to establish multihop
connectivity between endpoints. So, I am agreeing with your latter
sentence, but I would hesitate to call the nodes participating in
ad hoc networks to be "L2 networks" if each such "L2 network" only
has a single node...
What exactly would you do with an endpoint that was reachable only as
an L3 destination?
That would be a strange endpoint. Surely it would have
interfaces that would receive packets over layer 2...?
Is that the only issue? Then what you're talking about is "how to
model source-only or sink-only hosts in the Internet" - note I was
able to say this without needing any reference to a L2.
That is not our message at all. I don't think those terms appear
anywhere in the document, or in the discussions leading up to the
document in the other working groups.
If you're talking about nodes that are sometimes connected in one
direction then later connected in the other, that's just
long-timescale changes to links that affect communication - there's a
whole area of work addressing that (DTN).
I was not aware of any DTN discussion about this. Do you have
a pointer to a document? We are not dealing with long-timescale
changes, in fact just the opposite.
We are trying to encourage better designs for Internet protocols,
and equally well to encourage improvements for existing protocols
to enable them to run over such (multihop) networks.
Can you explain how your net is different from:
a) source-only or sink-only nodes
(which aren't relevant in a comm system)
b) DTN
I am somewhat at a loss, but I will try.
First, the effects described are not restricted to "my" net.
For (a): as one example, ad hoc networks contain the kinds of
nodes that are described in the document. Ad hoc networks *may*
also contain source-only or sink-only nodes, but that is not very
relevant to the discussion in the draft.
For (b): delay tolerance is not described in the draft. You might
characterize some of the effects as "disruption", but I don't think
that would lead to proper understanding.
So, I feel I am missing your point, or else there is a need for a
longer discussion about ad hoc networks. And yet, there are likely
other kinds of networks that would also benefit from understanding
the effects described in our draft. This is not to say that the effects
are new. Again, our experience motivates the need, and I believe
that that the draft properly documents effects that (even though
not new) are relevant to the design of Internet protocols.
Regards,
Charlie P.
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