sell shell accounts?

Sean Doran smd at
Wed Jul 24 02:16:03 UTC 1996

It's still ATM day, 'cause something else just occurred to

| Consider the following configuration
|    ________           _______________________          ________
|   | Router | loop A  |                       | loop C | Router |
|   |   A    |=========| Wide-Area ATM Service |========|   C    |
|   |________|         |_______________________|        |________|
|                                  |
|                                  | local loop B
|                                  |
|                              ________
|                             | Router |
|                             |   B    |
|                             |________|

How is one doing bandwidth allocation in this scheme?  Are
we assuming CBR (to be very conservative) (or VBR with V=0
for those that don't do CBR)?

If so, then local loop B is really two circuits, one of 
BW X and the other of BW 1-X.

Moreover, continuing with the thought of CBR or the
equivalent, if one has a hundred routers in one's network,
how does one allocate a fixed bandwidth from B to each
router?  Or does one overcommit and lean on UBR or ABR or
some other *BR?

These are serious questions I don't have an answer to, and
come a result of having remembered the paragraph below and
of remembering that a couple of our competitors have
very large (admittedly "Frame Relay") PVC meshes.


| The desire for a full mesh of VCs between routers becomes more compelling
| if you have more than three routers.  The diagram is left as an exercise
| to the reader; I rather dislike having to draw in ASCII.

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