On Tue, 8 Jun 2004, Joe Abley wrote:
International bandwidth still costs a lot, perhaps.
This (and Jonathan's answer) assumes that the introduction of caches somehow conserves bandwidth. I've never seen that in practice; the upstream pipes were still as full as ever the last time I watched caches being added to an ISP.
Well the graphs I look at have less bandwidth going in one direction than in the other. The difference being enough to pay for the cache boxes in a reasonable payback period. I wouldn't be surprised if price of bandwidth drops enough in a couple of years for it not to be worth doing however. I seem to remember back about 5 years ago the payback period for cache boxes plus a L4 interceptor was around 1 month. Anyway ISPs don't route most of their customer's traffic these days, Netgate does.
That caches improve perceived performance for users is a reasonable reason to the original question, I suppose. I've never heard of anybody using transparent caches without a regular stream of helpdesk driven exception handling, though, so there's a cost to that performance, both to the customer and to the ISP whose helpdesk phone is ringing.
Obviously if ISPs felt the TCO was positive then they would use it. They fact they they still use them indicates that they perceive the savings are still there. -- Simon J. Lyall. | Very Busy | Mail: simon(a)darkmere.gen.nz "To stay awake all night adds a day to your life" - Stilgar | eMT.