Re: Customer oversubscription levels

["Stephen J. Wilcox" <steve () opaltelecom co uk>]

I'd look at this slightly differently.. customers wont use all their
available bandwidth at once anyway so you will get aggregation simply by
economy of scale.

Compare to say the PSTN, there might be say 100000 local customer lines
attached to a particular exchange and yet the capacity out onto the trunk
network might be say 5000 lines. Clearly there is a high degree of over
subscription and phone customers are the first to complain when they cant
dial out and yet it doesnt happen because not everyone uses it at once.

The same is true for bandwidth, you can achieve a good level of
aggregation - say 5:1 and yet each customer can max out their own link
because they dont all do it at once

The problem comes when you either just dont have trunk capacity or you try
to put far too many customers onto a node. 

I always call it aggregation vs contention - in one you achieve economy of
scale and in the other you knowingly degrade service (within the bounds of
an SLA)

So, to answer your question, it depends what your selling as to how much
oversubscription you can achieve, anything for 3:1 to 20:1 depends on if
its transit, leased line, broadband, dialup... but I think you should look
more at whether you are actually degrading an individuals service or just
achieving aggregation.

Steve


On Tue, 28 May 2002, Mathew Lodge wrote:

> This might be a dumb question, but I can be sure that I'll be told if 
> that's the case, so here goes:
>
> What's a good oversubscription ratio for customer traffic to global 
> Internet bandwidth these days? I.e., if you have, say 90megs of bandwidth 
> to other transit providers, how much bandwidth, in aggregate, are you 
> selling to customers -- 90? 450? 900?
>
> Do customers care about this? Or do they assume that if they get a T1 to 
> the Internet from you that they have their own T1's worth of non 
> over-subscribed bandwidth to your transit providers?
>
> Thanks,
>
> Mathew