Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
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Chapter 2 Campus <strong>QoS</strong> <strong>Design</strong><br />
Version 3.3<br />
Catalyst 6500 PFC2/PFC3—<strong>QoS</strong> Considerations and <strong>Design</strong><br />
<strong>QoS</strong> is globally disabled by default on Catalyst 6500s running either CatOS or IOS. When <strong>QoS</strong> is<br />
globally disabled, then all frames/packets that are passed-through the switch remain unaltered (which is<br />
equivalent to a trust CoS and trust DSCP state on all ports). When <strong>QoS</strong> is globally enabled, however,<br />
then all DSCP and CoS values are (by default) set to 0 (which is equivalent to an untrusted state on all<br />
ports).<br />
The commands to enable and verify <strong>QoS</strong> globally on both CatOS and IOS Catalyst 6500s are shown<br />
below.<br />
Example 2-46 Enabling <strong>QoS</strong> Globally on a Catalyst 6500—CatOS<br />
CAT6500-PFC2-CATOS> (enable) set qos enable<br />
<strong>QoS</strong> is enabled.<br />
CAT6500-PFC2-CATOS> (enable)<br />
CAT6500-PFC2-CATOS> (enable) show qos status<br />
<strong>QoS</strong> is enabled on this switch.<br />
CAT6500-PFC2-CATOS> (enable)<br />
Example 2-47 Enabling <strong>QoS</strong> Globally on a Catalyst 6500—IOS<br />
CAT6500-PFC2-IOS(config)#mls qos<br />
CAT6500-PFC2-IOS(config)#end<br />
CAT6500-PFC2-IOS#<br />
CAT6500-PFC2-IOS#show mls qos<br />
<strong>QoS</strong> is enabled globally<br />
Microflow policing is enabled globally<br />
Vlan or Portchannel(Multi-Earl) policies supported: Yes<br />
----- Module [2] -----<br />
<strong>QoS</strong> global counters:<br />
Total packets: 65<br />
IP shortcut packets: 0<br />
Packets dropped by policing: 0<br />
IP packets with TOS changed by policing: 0<br />
IP packets with COS changed by policing: 0<br />
Non-IP packets with COS changed by policing: 0<br />
CAT6500-PFC2-IOS#<br />
Catalyst 6500—CatOS Defaults and Recommendations<br />
CatOS specifies a number of default <strong>QoS</strong> settings per-port, which do not appear in the normal<br />
configuration output. However it is beneficial to be aware of what these defaults are and what they do,<br />
so as not to override them by mistake.<br />
For example, CatOS allows the <strong>QoS</strong> policy-source to be defined by the local configuration or by the<br />
Common Open Policy Source (COPS) protocol, referring to a COPS Policy-Decision Point (PDP)<br />
Server. COPS is a <strong>QoS</strong> administration protocol that is both dynamic and scalable, but unfortunately it<br />
never gained mainstream acceptance. It is recommended to leave the switch’s default policy-source as<br />
local (except of course in the extremely rare occurrence that COPS is actually deployed on the network).<br />
<strong>Enterprise</strong> <strong>QoS</strong> <strong>Solution</strong> <strong>Reference</strong> <strong>Network</strong> <strong>Design</strong> <strong>Guide</strong><br />
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