acceptable interface saturation

[Wan_Whisperer]

What is acceptable interface saturation/utilization before an upgrade is needed?

The interface from my core router to my core switch is hitting about 50% utilization consistently. In the past, it was around 65% and I did not notice any issues. 

When does everyone recommend an upgrade to a new device?  (port channel is not possible)  

If you are in sales please do not reply, I am sure you will say now

-WW

[balaji.bandi · Accepted solution]

Most cases we can go up to 80-85% - also possible use QoS (where required to minimise and priortise the traffic)

This is not only one device you need to look Entire network where the origin traffic source coming from ?

[Joseph W. Doherty]

"What is acceptable interface saturation/utilization before an upgrade is needed?"

Very, very much an "it depends" answer.  Further, interface percentage usage often highly misunderstood.

Sometimes continuous 100% usage is just fine.  Sometimes low average usage is not fine. 

Going by general queuing theory, less that 1/3 usage is often fine.  Between 1/3 to 2/3 often okay.  Above 2/3, often congestion issues.

Again, though, what's good, or not, based on average utilization, is really, really variable.