Reference Guide

802 | Quality of Service
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Configure Port-based Rate Shaping
Rate shaping buffers, rather than drops, traffic exceeding the specified rate until the buffer is exhausted. If
any stream exceeds the configured bandwidth on a continuous basis, it can consume all of the buffer space
that is allocated to the port.
Apply rate shaping to outgoing traffic on a port using the command
rate shape from INTERFACE mode,
as shown in the example below.
FTOS#config
FTOS(conf)#interface gigabitethernet 1/0
FTOS(conf-if)#rate shape 500 50
FTOS(conf-if)#end
FTOS#
FTOS Behavior:
Rate policing is supported only on physical port interfaces; it is not supported on port-channel and
VLAN interfaces.
- On ExaScale, when rate shaping is configured on an interface, the “Dropped Packets” counter in the
outputs of show queue statistics egress and show qos statistics wred-profile does not increment. This
is because, while TeraScale systems maintain QoS counters per interface, ExaScale systems
maintain QoS counters per port-pipe. The matched packets counter, however, increments as
expected.
- On ExaScale 10G line cards, the granularity for rate shaping is 10Mbps so traffic is not always rate
shaped according to the configured value. Specifically, if the configured value is below 5Mbps or a
multiple of 5: for values less than 5Mbps, 0Mbps is received at remote end, and for values greater than
or equal to 5Mbps, the remote end receives the next highest increment of 10; 15Mbps, for example, is
rate shaped to 20Mbps.