The IOS calculates statistics (including load) over some interval which can be controlled using the load-interval command. 30 seconds is the smallest interval that can be configured. There may be advantages to longer intervals and advantages to shorter intervals. If you use the longer interval (which is the default) you get more of a big picture of what the router is doing. But the longer interval tends to hide the impact of bursty traffic. By setting the load-interval to a shorter value you may see more easily the impact of bursty traffic but may have more difficulty in seeing the bigger picture of what is happening with the interface. Deciding on which is better depends very much on your local situation and on what you are trying to look at.
Since the interface statistics are calculated more frequently one could make an argument that in absolute terms yes it uses more CPU cycles to lower the interval from 5 minutes to 30 seconds. In a practical sense there is no noticeable impact on the router. It certainly does not cause anything to work differently.
Thanks, Rick. I thought that might be the case, as I couldn't find anything stating it would be impactful, but I did see one post where a user recommended returning the load-interval to default while troubleshooting performance problems. My system is a 4506 w/ Sup IV. I wanted to change to 30 second interval on the trunk ports to access switches (physical and port-channel). Thanks.
It is usually good advice to return things to default values that you changed while troubleshooting.
Depending on how you want to use the interface statistics the default of 5 minutes may be too long to be useful. Especially in the case where there is bursty traffic you probably want more detail to show up with a shorter interval. I do not think that you should worry about changing the load interval on your switch ports.
"It certainly does not cause anything to work differently."
BTW: I believe OER/PfR bases it link load analysis on the interface's load interval setting. If my belief is correct, interface load interval setting would impact how often OER/PfR might shift routes if it's balancing load.
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