TP-5-DOMAINMISMATCH: Unable to perform trunk negotiation on port Gi1/0/20 because of VTP domain mismatch. In this case, changing the domain results in a VTP domain mismatch that will prevent trunk negotiation from occurring on port G1/0/20. Configuring VTP CatOS You can set or change the VTP domain on CatOS with the set vtp domain command: Switch1-Catos# (enable)set vtp domain GAD-Lab VTP domain GAD-Lab modified In this case, I resolved the trunk issue, SO no error was reported. Had my change resulted in a VTP domain mismatch, the switch would have alerted me with a similar message to the one reported on the IOS switch. NX-OS VTP is a feature in NX-OS that must be enabled before use (see Chapter 18 for more information on features): NX-7K-1-Daisy (config)# feature vtp As of this writing, Nexus 7000s will only operate in transparent mode, while Nexus 5000s will only operate in VTP mode off. Since the Nexus will not actively participate in VTP, there is no reason to set a VTP password: NX-7K-1-Daisy (config)# vtp mode ? transparent Set the device to transparent mode This Cisco documentation has this to say about VTP on Nexus 5000s: VLAN Trunking Protocol (VTP) mode is OFF. VTP BPDUs are dropped on all interfaces of a Cisco Nexus 5000 Series switch, which partitions VTP domains if other switches have VTP turned on. You can see details regarding VTP on a Nexus 7000 with the show vtp status command: NX-7K-1-Daisy (config)# sho vtp status VTP Version Configuration Revision Maximum VLANs supported locally : 1005 VTP Operating Mode : Transparent VTP Domain Name : accounting VTP Pruning Mode : Disabled VTP V2 Mode : Enabled VTP Traps Generation : Disabled VTP Mode Chances are, you will need to change the default VTP mode on one or more switches in the VTP domain. When this is the case, you'll need the relevant commands for IOS and CatOS. There are three VTP modes on an IOS-based switch: server, client, and transparent. They are set using the vtp mode command: Chapter 6: VLAN Trunking Protocol 3750-I0S(config)#vtp mode ? c