Quick Reference Guide

424 PowerConnect B-Series TI24X Configuration Guide
53-1002269-02
Rate shaping overview
16
Rate shaping overview
Outbound Rate Shaping is a port- level feature that is used to shape the rate and control the
bandwidth of outbound traffic on a port. This feature smooths out excess and bursty traffic to the
configured maximum limit before it is sent out on a port. Packets are stored in available buffers
and then forwarded at a rate no greater than the configured limit. This process provides for better
control over the inbound traffic of neighboring devices.
The device has one global rate shaper for a port and one rate shaper for each port priority queue.
Rate shaping is done on a single-token basis, where each token is defined to be 1 byte.
Configuration notes
The following rules apply when configuring outbound rate shapers:
• Outbound rate shapers can be configured only on physical ports, not on virtual or loopback
ports.
• For trunk ports, the rate shaper must be configured on individual ports of a trunk using the
config-trunk-ind command (trunk configuration level); you cannot configure a rate shaper for a
trunk.
• When outbound rate shaping is enabled on a port on an IPv4 device, the port QoS queuing
method (qos mechanism) will be strict mode. This applies to IPv4 devices only. On IPv6
devices, the QoS mechanism is whatever method is configured on the port, even when
outbound rate shaping is enabled.
• You can configure a rate shaper for a port and for the individual priority queues of that port.
However, if a port rate shaper is configured, that value overrides the rate shaper value of a
priority queue if the priority queue rate shaper is greater than the rate shaper for the port.
• On PowerConnect B-Series TI24X devices, configured rate shaper values are rounded up to the
nearest values programmable by the hardware.
Configuring outbound rate shaping for a port
To configure the maximum rate at which outbound traffic is sent out on a port, enter commands
such as the following.
PowerConnect(config)#interface e 2
PowerConnect(config-if-e10000-2)#rate-limit output shaping 1300
• On PowerConnect B-Series TI24X devices, the configured 1300 Kbps outbound rate shaping
on port 2 is rounded up to the nearest value programmable by the hardware, which is 1344
Kbps. This value is the actual limit on the port for outbound traffic.
Syntax: [no] rate-limit output shaping <value>
Configured Input Rate The maximum rate requested for inbound traffic. The rate is measured
in or kilobits per second (kbps) for PowerConnect devices.
Actual Input Rate The actual maximum rate provided by the hardware. The rate is
measured in kilobits per second (kbps) for PowerConnect devices.
TABLE 68 CLI display of Fixed Rate Limiting information (Continued)
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