What frame relay switch is causing MCI/Worldcom such grief?

Tue Aug 10 21:25:14 UTC 1999

Dave Cooper <dcooper at eli.net> wrote:

> The problem is not capacity planning.  Most large
> backbones have dedicated resources to determine
> 6-12 month needs in their cores. There are good
> tools to help you do that, not to mention good ole'
> regression analysis along with programs like Wandl.
> But those statistical tools will only go for 12 months
> out with a "decent" deviation. Once you
> go any further, you are grabbing at straws.

The rule of thumb: build as big network as you can and
then connect only as many customers as it can sustain :)

Seriously, TCP/IP can accomodate very gross mistakes in
capacity planning - up to an order of magnitude.  Trivial
trend analysis and random traffic distribution gives
predictions which are good enough.  In fact, there are
no good ways to measure demand for data traffic -- the
actual traffic measurements reflect the current available
capacity and effects of routing decisions more than anything
else, and only show pathologically bad capacity problems.

>The problem lies with the provisioning times for
>circuits at the OC-3/OC-12/OC-48 level.

That problem should have non-technical solution.  Fix
telco bureaucracy.  Or just let the sluggish ones die;
everybody will be better off for that.

> This creates
> the need to use existing resources to reduce latency
> and delay until you can bring the physical topology
> to specification.

This creates the need to worry about more than the
short term revenue, and to actually listen to what
engineers have to say.  The problem is not technological,
and no technological fix is going to cure it - any such
fix only masks the symptoms, simply prolonging the agony
and draining scarce engineering resources.

>I highly doubt the big players are looking at MPLS
>to bail themselves out of the physical topology
>constraints (although that might be a side benefit
>for both the provider AND the customer).

They're introducing a whole new can of worms complexity-wise
for something which at best promises 10-20% improvement
(bandwidth utilization-wise; the latency-related actual
performance degradation makes even that benefit highly
doubtful).  2 months of advantage just do not worth it.
Customers increasingly are limited by server capacity, and
worry a lot more about availability than about backbone
capacity.

--vadim