C type-1 configuration incompatible - STP interface port type inconsistent If that looks bad, it's because it is. The configuration of the vPC no longer matches between the switches, SO the Nexus essentially disabled it. Now, in theory, the vPC should break, and one of the links will stay up, allowing traffic to flow. There should be no outage, but I've seen the server guys gripe every time we did this, and in the days Nexus Design Features before config-sync, that meant no changes outside of scheduled outages-and in this type of environment, there were never scheduled outages. As soon as we added the command to the other switch, thereby making the configu- rations match again, the vPC came back online. No matter how quickly we thought we could configure both switches-even pressing the Enter key on two computers at the same moment-it wasn't fast enough, and the vPCs would go through this maddening process. Config-sync is designed to alleviate this type of problem. In a nutshell, two Nexus switches are paired together over the mgmt0 interface. Configuration commands are loaded into a buffer on one of the switches, and when the commit command is executed, the commands are simultaneously entered on both switches. Sounds great, and it is, but there are some drawbacks. The first thing to remember is that, as of this writing, only commands that have to do with vPCs and FEXs are supported. You cannot sync the configs of your Ethernet in- terfaces, for example. The second thing to remember is that though your synced commands will show up in the output of show run, they're not really there. To work with config-sync, we must enter a new configuration mode called, surprisingly, configure sync: NX-5K-1# configure sync Enter configuration commands, one per line. End with CNTL/Z. You might be tempted to think that anything you type here will be replicated to the other switch, but you'd be wrong. First, we haven't told it what the other switch is yet, and second, that would be too simple, and thus no fun. Switch commands in syn