Link capacity upgrade threshold

William Herrin herrin-nanog at
Sat Aug 29 23:15:36 CDT 2009

On Sat, Aug 29, 2009 at 11:50 PM, devang patel<devangnp at> wrote:
> I just wanted to know what is Link capacity upgrade threshold in terms of %
> of link utilization? Just to get an idea...

If your 95th percentile utilization is at 80% capacity, it's time to
start planning the upgrade. If your 95th percentile utilization is at
95% it's time to finish the upgrade.

If you average or median utilizations are at 80% capacity then as
often as not it's time for your boss to fire you and replace you with
someone who can do the job.

Slight variations depending on the resource. Use absolute peak instead
of 95th percentile for modem bank utilization -- under normal
circumstances a modem bank should never ring busy. And a gig-e can run
a little closer to the edge (percentage-wise) before folks notice
slowness than a T1 can.

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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