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Nexus Switching 2nd Edition

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with previous steps, these port-channels will be configured on both sides <strong>and</strong> set to<br />

administratively disabled on the 6500 side of the link initially, <strong>and</strong> then enabled in a<br />

controlled fashion.<br />

Design Note<br />

Care has been given to distribute port-channel members acr<strong>os</strong>s multiple linecards.<br />

This ensures that no single module failure results in a major L2 topology change.<br />

One additional concern of Acme, Inc., is that its existing devices have been left with per-<br />

VLAN spanning-tree (PVST). As discussed in Chapter 2, the Nexus switches support only<br />

Rapid-PVST+ <strong>and</strong> MST. Although Rapid-PVST+ is backward compatible with PVST,<br />

Acme views relying on this backward compatibility as unwanted. Because of the increased<br />

reliance on Layer 2 in the new design, the existing devices will be converted to Rapid-<br />

PVST+. This will ensure the fastest p<strong>os</strong>sible reconvergence should the Layer 2 topology<br />

change.<br />

Examples 14-11 <strong>and</strong> 14-12 illustrate the interface configuration elements of Denmark <strong>and</strong><br />

Scotl<strong>and</strong> for their migration to the Nexus switches.<br />

Example 14-11. Port-Channel Configuration on SSA (Denmark)<br />

Click here to view code image<br />

denmark# conf t<br />

denmark(config)# interface GigabitEthernet1/3<br />

denmark(config-if)# description VPC member<br />

denmark(config-if)# switchport<br />

denmark(config-if)# switchport trunk encapsulation dot1q<br />

denmark(config-if)# switchport trunk allowed vlan<br />

26,57,208,209<br />

denmark(config-if)# switchport mode trunk<br />

denmark(config-if)# channel-group 100 mode passive<br />

denmark(config-if)#<br />

denmark(config-if)# interface GigabitEthernet1/4<br />

denmark(config-if)# description VPC member<br />

denmark(config-if)# switchport<br />

denmark(config-if)# switchport trunk encapsulation dot1q<br />

denmark(config-if)# switchport trunk allowed vlan<br />

26,57,208,209<br />

denmark(config-if)# switchport mode trunk<br />

denmark(config-if)# channel-group 100 mode passive<br />

denmark(config-if)#<br />

denmark(config-if)# interface GigabitEthernet2/3<br />

denmark(config-if)# description VPC member

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