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Cat 6500 Vlan QoS policing, how much bandwidth for class-default

I was looking at a problem where a traffic from certain sites have a restricted bandwidth, an ongoing problem for a year or so, apparently this throughput never exceeds around 25Mbps. My customer describes a situation where the end to end utilisation rises, eventually flat-lining at around 25Mbps. Regardless of how many extra systems come on line, this traffic never exceeds this rate, and end users complain of poor responses.

During my investigation I found that one of the switches (Cat 6509) in the traffic path has a policer configured on a vlan interface, the policer has 3 sections for different traffic based on DSCP markers, and a default (unconfigured) class-default. Various people have had a poke about with this config over the years, with the result that all the traffic has the CoS and DSCP tags set to 0. All this traffic is hitting the class-default in the policer.The link that this traffic hits the Cat 6509 on is a 100Mbps link.

If I was designing this from scratch I'd probably configure a rate for the class-default.

So, my question is, in the case where no specific configuration has been entered for the class-default, how much bandwidth is allocated to this class?


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Cat 6500 Vlan QoS policing, how much bandwidth for class-default


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Usually, any one class of traffic can use all possible bandwidth, unless otherwise restricted as in your case if a policer is being used.  If there are multiple classes of traffic, assuming there are multiple queues, often the default is equal sharing of bandwidth, although the most common default is just one FIFO queue for all traffic.