d Interface-vlan admin up Allowed VLANs Local suspended VLANs Config-Sync Version 5.0(2)N1(1) of NX-OS on the 5000s introduced a feature called config-sync. This feature is useful because there are other features that require the configurations of two Nexus switches to be at least partially synchronized. Two examples that have bitten me are cross-connected FEXs (see "Configuring Fabric Extenders (FEXs)" on page 290) and vPCs (see "Virtual Port Channel" on page 294). vPCs in particular suffer from a maddening willingness to break anytime there is a configuration inconsistency between the two Nexus switches to which they are bound. Chapter 18: Cisco Nexus Imagine two Nexus 5010s, with large blade servers connecting via 10 Gbps trunks. The blade servers require redundancy, SO we create a nice vPC between the two Nexus 5Ks. The blade server sees the EtherChannel, and everything works beautifully. The config for the blade chassis trunk might look something like this (replicated on each Nexus): interface port-channel 10 description BladeServer switchport mode trunk switchport trunk allowed vlan 10,20,30,40 vpc 10 Everything is working fine, until one day we decide that we need to change the spanning tree port type. It doesn't matter why, other than that if this isn't changed in the next 10 minutes, you'll be fired. You know-a typically well-planned change. The spanning- tree port type edge trunk command is added to NX-5K-1 with some unfortunate results. As soon as we change the first 5K, the vPCs break: NX-5K-1(config-if)# sho vpc Legend: (*) - local vPC is down, forwarding via vPC peer-link vPC domain id Peer status peer adjacency formed ok vPC keep-alive status peer is alive Configuration consistency status success Per-vlan consistency status : success Type-2 consistency status : success vPC role : primary Number of vPCs configured Peer Gateway : Disabled Dual-active excluded VLANs Graceful Consistency Check : Enabled vPC Peer-link status Status Active vlans vPC status Status Consistency Reason Active vlans failed vP