I dated a topologist once. Really I did. He claimed the most useful thing
he learned from his studies was how to get a woman's brassiere off without
taking her blouse off. ;-) It is possible, assuming a certain level of
stretchiness.
He also claimed that, topologically, a donut and a coffee cup are the same
shape. Think about it!
Priscilla
At 01:36 PM 5/26/2000 -0400, Howard C. Berkowitz wrote:
>>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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__________________________________
Priscilla Oppenheimer
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