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Nexus Switching 2nd Edition

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Nexus devices enable class maps to be applied for different applications lending additional<br />

flexibility. These types fall into three distinct categories:<br />

• QoS for packet classification<br />

• Network-QoS for systemwide marking <strong>and</strong> congestion control<br />

• Queuing for scheduling of traffic<br />

The Nexus 7000 also supports an additional type for the control plane. Example 10-2 shows<br />

these types.<br />

Example 10-2. QoS Types<br />

Click here to view code image<br />

N7K-2# show policy-map type ?<br />

control-plane Comm<strong>and</strong> is for copp policy<br />

network-q<strong>os</strong> Type network-q<strong>os</strong><br />

q<strong>os</strong><br />

Type q<strong>os</strong><br />

queuing Type queuing<br />

N7K-2#<br />

Looking at these types more cl<strong>os</strong>ely shows that each type has its specific function <strong>and</strong> role<br />

within the switch. The q<strong>os</strong> type is used for classification <strong>and</strong> marking of traffic. This is<br />

usually the first step in defining a QoS policy <strong>and</strong> allows for granular control of what traffic<br />

is classified or marked to a specific value. Referring to Example 10-1, you see the access<br />

list was very specific to match traffic from a subnet that was also Telnet traffic. Access lists<br />

can be broad or as focused as required.<br />

QoS classes are not restricted to just using ACLs to classify traffic. Additional granularity<br />

can be added by matching against c<strong>os</strong>, dscp, ip rtp ports, precedence, or predefined<br />

protocols, as shown in Example 10-3.<br />

Example 10-3. Classification Matches<br />

Click here to view code image<br />

N5K-1# config<br />

Enter configuration comm<strong>and</strong>s, one per line. End with<br />

CNTL/Z.<br />

N5K-1(config)# class-map cm-match-telnet<br />

N5K-1(config-cmap-q<strong>os</strong>)# match ?<br />

access-group Access group<br />

c<strong>os</strong><br />

IEEE 802.1Q class of service<br />

dscp<br />

DSCP in IP(v4) <strong>and</strong> IPv6 packets<br />

ip<br />

IP

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