On 27/02/2015 2:50 PM, William Herrin wrote:
On Fri, Feb 27, 2015 at 2:22 PM, Scott Helms <khelms@zcorum.com> wrote:
I have to take exception to your example.
Water, gas, and to a great extent electrical systems do not work on oversubscription, ie their aggregate capacity meets or exceeds the needs of all their customers peak potential demand, at least from "normal" demand standpoint.
Hi Scott,
Do you propose that Internet access service should NOT be expected to meet peak "normal" demand? That would certainly make ISP operating models unique among public utilities.
Regards, Bill Herrin
I've worked on both data network (Canada's X.25 Datapac) and circuit-switched network provisioning (Nortel's DMS switches, and some of my contributions appear in the ITU-T Orange Book). Circuit-switched provisioning had the useful concept of "grade of service". This meant that you set a target probability of delay or loss for a given load level on the network (Average Busy Season Busy Hour, 10 High Day Busy Hour, separate targets for each and provision to the most binding). The same general concepts surely apply to IP network provisioning: you know you can't economically serve all the traffic at the absolute peak, but you set reasonable targets, assure yourself by simulation and analysis that your design will meet the target, and build accordingly. Tom Taylor