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I have different switches and each switch has different cos-weight.

Now, it has cos3-weight, cos4-weight and cos5-weight in one switch as 15. In other it is 30.

As per this link : https://techdocassets.pluribusnetworks.com/UNUM/unum630/QOS-CPUCoSWeight.html

I can see a bit of definition but its still not clear.

  1. can it be traffic hampering if I change the cos-weight?
  2. Why is it important to change the cos-weight?
  3. What is the difference between cos3-weight, cos4-weight and cos5-weight?

Thank you in advance.

Regards, Tayto

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Can it be traffic hampering if I change the cos-weight?

The Class of Service (not Server) allows you to give priority to some traffic over other, based on the CoS value. What is important is the relative values between the different CoS.

If you change the value, you are changing the minimum percentage of switch forwarding capacity. Normally, the default values are good for most situations.

Unless you have a specific need, you shouldn't change the values. If could affect traffic if your switch is prone to congestion (i.e., is oversubscribed)

Why is it important to change the cos-weight?

If you have traffic with different latency or bandwidth requirements, the CoS weight allocates switch resources based on the CoS value -- the higher the weight, the more resources that traffic gets.

What is the difference between cos3-weight, cos4-weight and cos5-weight?

The default values are the same for each weight. That means they are all treated the same.

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  • So, if the cos weight is wrong for a few Pluribus switches(lower than the value needed) and needs to be changed to the correct number(higher value), that won`t hamper the traffic if we change it to the valid value, right? @Ron Trunk
    – Tayto
    Commented May 17, 2022 at 7:42
  • @Tayto The "right" values depend on how you intend to model the traffic flows. They entirely depend on your network design which we know nothing about. I assume the changes weren't done on purpose or exist for some legacy reason, so likely nothing is going to happen when you make them all default.
    – Zac67 ♦
    Commented May 17, 2022 at 8:28
  • It's hard to answer without knowing more about your network and the kinds of traffic you have. But I agree with @Zac67 that it's probably OK. If you were doing layer 2 QoS, you'd probably know about it.
    – Ron Trunk
    Commented May 17, 2022 at 13:09

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