Configuring QoS QoS Ports and Queues
OmniSwitch 6800/6850/9000 Network Configuration Guide March 2008 page 30-27
Bandwidth Shaping
Bandwidth shaping is configured on a per port basis. Bandwidth policing is applied using QoS policies
(see “Port Groups and Maximum Bandwidth” on page 30-48 and “Policy Applications” on page 30-57 for
more information).
QoS supports configuring maximum bandwidth on ingress and egress ports. However, on the OmniSwitch
6850 and 9000 switches, configuring minimum and maximum egress bandwidth is supported on a per
COS queue basis for each port (see “Configuring the Egress Queue Minimum/Maximum Bandwidth” on
page 30-27 for more information).
To limit the ingress or egress bandwidth for a QoS port, use the qos port maximum egress-bandwidth or
qos port maximum ingress-bandwidth commands. For example,
-> qos port 1/1 maximum egress-bandwidth 10M
-> qos port 1/1 maximum ingress-bandwidth 5M
Note the following when configuring the ingress or egress bandwidth limit for a port:
• Maximum bandwidth limiting is done using a granularity of 64K bps. Any value specified that is not a
multiple of 64K is rounded up to the next highest multiple of 64K.
• The maximum bandwidth value cannot exceed the maximum bandwidth of the interface type associ-
ated with the port.
• Modifying the maximum bandwidth is most useful for low-bandwidth links.
• The bandwidth limit configured using the qos port maximum egress-bandwidth command takes
precedence over an egress queue limit configured on the same port.
• Configuring the maximum ingress bandwidth value is not supported on an OmniSwitch 6800.
Configuring the Egress Queue Minimum/Maximum Bandwidth
Configuring a minimum and maximum bandwidth value for each of the eight egress port queues is
allowed on the OmniSwitch 6850 and 9000 but is not supported on the OmniSwitch 6800. By default the
bandwidth values are set to zero, which means best effort for the minimum bandwidth and port speed for
the maximum bandwidth.
To configure the bandwidth values use the qos port q minbw maxbw command. For example, the follow-
ing command sets the minimum and maximum bandwidth for queue 8 on port 2/10 to 2k and 10k:
-> qos port 2/10 q8 minbw 2k q8 maxbw 10k
Note that specifying both the minimum and maximum bandwidth value is allowed on the same command
line. Configuring the bandwidth values for different queues requires a separate command for each queue.
Trusted and Untrusted Ports
By default switch ports are not trusted; that is, they do not recognize 802.1p or ToS/DSCP settings in
packets of incoming traffic. When a port is not trusted, the switch sets the 802.1p or ToS/DSCP bits in
incoming packets to the default 802.1p or DSCP values configured for that port.
The qos port default 802.1p and qos port default dscp commands are used to specify the default 802.1p
and ToS/DSCP values. If no default is specified, then these values are set to zero.
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