>Hi, all
>
>At the risk of touching off a word war here, I wanted to see if I could
>get some verification from the group. This is sort of a Howard B.
>question in that it has philosophical undertones. What I am trying to
>accomplish is to cement my understanding of the terms below.
Wondering if it is better or worse to be typecast as a network
philosopher or a network theologian.
>
>I have been studying OSPF very heavily, and as you know, OSPF can pretty
>much work over anything. It is the MIRACLE routing protocol, if you ask
>me. However, OSPF can be confounding in that it can treat the
>underlying network as something that it is not. For example, OSPF can
>run on a broadcast network as it the broadcast network were actually a
>point to multipoint network by executing the command ip ospf network
>point-to-multipoint. This brings me to the point of my post:
>
A couple of quotes come to mind. Butler Lampson once said "There is
no problem in computer science that is not solvable with a sufficient
level of indirection."
There's a tale told of Stephen Hawking giving a lecture on the
origins of the universe. Afterwards, a very proper dowager came up
to him and said, "Young man, I don't hold with these big bang
theories. The ancient Chinese understood these things properly, with
their legend that the world stands on the back of a giant turtle."
Hawking, no fool he, responded, "But on what does the turtle stand?"
"Another turtle."
Hawking, seizing on a potential weakness, started to ask the obvious
question, but his questioner cut him off. "And before you ask what it
stands on, it's turtles all the way down."
>
>What is the topology in my example? Broadcast? Point to multipoint?
>Bus?
>What is the network technology? Broadcast (such as Ethernet).
>What is the OSPF network type? Point to multipoint (as set by me).
>
I would prefer to say that you are dealing with several levels of
virtualization or abstraction.
There is the abstraction seen by OSPF.
There is the abstraction seen by IP.
There is the abstraction seen by the MAC sublayer.
Each of these abstractions has a topological view, or, perhaps more
correctly from a mathematical standpoint, assumes a different graph.
Bearing in mind the very proper corrections I have undergone from Dr.
Peter Welcher on being imprecise with mathematical terminology, I no
longer throw around the term topology with great abandon. Pete, if
you are reading this, please join in!
>
>Would it be accurate to say that term, "network topology" describes the
>arrangement of the network's links or amount of connectivity between the
>routers on the network? On a broadcast network, what is the topology?
>Would I consider it to be fully meshed as each router on a broadcast
>network such as Ethernet would have a link to every other router? Or
>does network topology describe an integration of the links and the
>network technology?
Unfortunately, you are running into the problem of using natural
language to describe formal systems.
>
>Network technology is an easy one to define, so I think. It is the
>complete _____________ compromising access methods, packet formation,
>transmission methods, and so on. I am not sure what would fill in the
>blank best: protocol? suite? means? mechanism?
Informally, I tend to call what I think you're describing a "protocol
stack." When I was working in formal OSI protocol stuff, we called
it a "functional profile," defined as a set of protocols and a set of
protocol options at each layer.
>
>OSPF network types are OSPF's description of what it or you describe the
>network as. It does NOT have to match the actual topology of the
>network.
The network types are less a medium type description as a set of
rules for finding neighbors and adjacencies
>
>Full mesh vs. partial mesh are somewhat easy to understand (amount of
>connectivity between network devices on a network). Would it be fair to
>say that the amount of meshing defines the topology?
>
>I feel better after sharing my muddled thoughts with the group. Am I
>overthinking this?
>
>Flames to: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
>
>Somewhere on the tank range...
>
>Charles
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