Cell Relay Archive

[guru@deltanet.com (Bill Schultz)]

In <fmo.74.000D45C4@info.fundp.ac.be>, fmo@info.fundp.ac.be (Frederic Mottiat) writes:
>I would like to know what are the advantages / drawbacks of turning an 
>ethernet backbone into an ATM backbone, in terms of speed, ease of use, .......
>
>Please, if you have any answers for me, do include technical arguments, no
>"emotional" ones :-)

I believe that the significant advantage to using an ATM backbone is to allow
microsegmentation of the LAN, which results in a higher bandwidth and a lower
latency delivered to each LAN user.

Let me recommend a couple of technical articles that will elaborate on my point.
Both of these are on the cisco web server:

     Select:  http://cio.cisco.com
     Select:  "Guest User"
     Select:  "Product Information"
     Select:  "Brochures"
     Select:  Under "Statements of Direction," "CiscoFusion Architecture" and
     Select:  Under "White Papers,: "CiscoFusion: An Architecture for Switched
          Internetworks."

>From the end user perspective, there would seem to be only advantages.

>From the system administrator perspective, you would have more tools available
to try and isolate users who are making demands for bandwidth which would
be unsupportable in an ethernet backbone arena (even "new" ethernet).  It is
difficult to characterize replacing nothing with something such that the something
results in easier use.  So, one drawback is that the system administrator would
have to actually use the management tools available for bandwidth management.

Of course, the obvious drawback is that the boxes to do all this are not free.

So, it is simply a question of bandwidth supply and demand on your ethernet LAN.
If your users have an adequate amount of available bandwidth, then you do not
need to microsegment your LAN to provide increased bandwidth.  If your users
do NOT have enough available LAN bandwidth to keep them happy, the only
alternative is to spend some money to segment the LAN.  An ATM backbone is
the obvious end-point, but as the above articles clearly explain, there are some
stops along the way that would provide intermediate solutions.

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