You connect a FEX to a Cisco Nexus switch. After configuration is complete, you issue the show fex 100 command on the switch and receive the following partial output:
Switch#show fex 100
<output omitted> Pinning-mode: static Max-links: 1 Fabric port for control traffic: Po100 Fabric interface state: Po100 – Interface Up. State: Active Eth1/1 – Interface Up. State: Active Eth1/2 – Interface Up. State: Active Eth2/1 – Interface Up. State: Active Eth2/2 – Interface Up. State: Active
Which of the following is true?
- The fex associate Eth2/1 command has been issued on the Po100 interface.
- The fex associate Eth2/2 command has been issued on the Po100 interface.
- The fex associate Eth1/1 command has been issued on the Po100 interface.
- The fex associate 100 command has been issued on the Po100 interface.
- The fex associate Eth1/2 command has been issued on the Po100 interface.
The fex associate 100 command has been issued on the Po100 port-channel interface in this scenario. There are two methods for connecting a Cisco fabric extender (FEX) to a Cisco Nexus switch: static pinning and port channel. In this scenario, the output of the show fex 100 command on the Nexus switch indicates that four Nexus switch physical interfaces and one port channel have been associated with the FEX: Ethernet 1/1, Ethernet 1/2, Ethernet 2/1, Ethernet 2/2, and P0100. In addition, the Po100 port channel is acting as the FEX fabric port.
To associate a port channel with a FEX, you should first create the port channel, configure the port channel to support a FEX, and then associate the port channel with a specific FEX. For example, the following commands configure Po100 on a Cisco Nexus switch to support a FEX and associate with FEX 100:
interface port-channel 100
switchport mode fex-fabric
fex associate 100
The switchport mode fex-fabric command and the fex associate 100 command should also be issued on each physical port that is a member of Po100’s channel group 100.
None of the other commands in this scenario could be issued on the Cisco Nexus switch, because they all contain invalid syntax. The syntax of the fex associate command is fex associate FEX-number, where FEX-number is the FEX chassis ID that is assigned to the FEX. Chassis IDs are assigned by the administrator and are valid in the range from 100 through 199. Chassis ID values less than 100 are typically ports on the parent switch. Ports on a FEX device are identified by chassis number, slot number, and port number. For example, a FEX interface might be identified as Ethernet 100/1/1, which indicates the interface in FEX 100 slot 1, port 1.