Cisco N7K-C7010 Configuration Guide - Page 220

Information About vPCs Chapter 7 Configuring vPCs Send document comments to [email protected] To ensure that all the configuration parameters are compatible, we recommend that you display the configurations for each vPC peer device once you configure the vPC. Consequences of Parameter Mismatch In releases earlier than Cisco NX-OS Release 5.2(1), when a consistency check detects a mismatch in a parameter from the list of parameters that must be identical, the vPC peer link and vPC are prevented from coming up. If a parameter mismatch is configured after the vPC is already established, the vPC moves into suspend mode and no traffic flows on the vPC. Beginning with Cisco NX-OS Release 5.2(1), you can configure the graceful consistency check feature, which suspends only the links on the secondary peer device when a mismatch is introduced in a working vPC. This feature is configurable only in the CLI and is enabled by default. Use the graceful consistency-check command to configure this feature. As part of the consistency check of all parameters from the list of parameters that must be identical, the system checks the consistency of all VLANs. In releases earlier than Cisco NX-OS Release 5.2(1), if the configuration of any enabled VLAN is inconsistent across the peer devices, the vPC is prevented from establishing or moves into a suspended mode. Beginning with Cisco NX-OS Release 5.2(1), the vPC will remain operational, and only the inconsistent VLANs will be brought down. This per-VLAN consistency check feature cannot be disabled and does not apply to Multiple Spanning Tree (MST) VLANs. vPC Number Once you have created the vPC domain ID and the vPC peer link, you create port channels to attach the downstream device to each vPC peer device. That is, you create one port channel to the downstream device from the primary vPC peer device and you create another port channel to the downstream device from the secondary peer device. Note We recommend that you configure the ports on the downstream devices that connect to a host or a network device that is not functioning as a switch or a bridge as STP edge ports. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.x, for more information on STP port types. Finally, working on each vPC peer device, you assign a vPC number to the port channel that connects to the downstream device. You will experience minimal traffic disruption when you are creating vPCs. To simplify the configuration, you can assign the vPC ID number to every port channel to be the same as the port channel itself (that is, vPC ID 10 for port channel 10). Note The vPC number that you assign to the port channel connecting to the downstream device from the vPC peer device must be identical on both vPC peer devices. Moving Other Port Channels into a vPC Note You must attach a downstream device using a port channel to both vPC peer devices. 7-18 Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide, Release 5.x OL-23435-03