Turn scheduler weights into a real bandwidth share and estimate serialisation and queueing delay per class.
A weighted scheduler hands out service in proportion to weight, so the bandwidth a class receives is its weight divided by the total. Serialisation is how long one packet takes to clock onto the wire, and the worst-case delay a packet sees is the whole queue ahead of it draining at the class rate. Weights are dimensionless in the CLI, so the only way to know whether a class will meet a 30 ms budget is to convert weight into Mbps and multiply by the configured queue depth.
Packet Scheduling
class share = weight ÷ sum of weights; queueing delay = queue depth × packet bits ÷ class bandwidth.
class share = weight ÷ sum of weights; queueing delay = queue depth × packet bits ÷ class bandwidth. A weighted scheduler hands out service in proportion to weight, so the bandwidth a class receives is its weight divided by the total. Serialisation is how long one packet takes to clock onto the wire, and the worst-case delay a packet sees is the whole queue ahead of it draining at the class rate.
Weights are dimensionless in the CLI, so the only way to know whether a class will meet a 30 ms budget is to convert weight into Mbps and multiply by the configured queue depth.
This calculator takes 5 inputs: Link rate, Weight of this class, Sum of all other weights, Average packet size, Queue depth. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.