Last Updated on August 3, 2021 by Admin
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: Eth2/1 Fabric interface state: Eth2/1 - Interface Up. State: Active Eth2/2 - Interface Up. State: Active
Which of the following is most likely true?
- Which of the following is most likely true?
- The switch is connected to the FEX by using port channel, but the configuration is not complete.
- The fex associate 100 command has been issued on the Po100 interface.
- The switch is connected to the FEX by using static pinning.
Of the available choices, it is most likely that the switch is connected to the Cisco fabric extender (FEX) by using static pinning. There are two methods for connecting a FEX to a Cisco Nexus switch: static pinning and port channel. The static pinning method connects a switch to a FEX by using individual links between the two devices. Host interfaces are then distributed among the available fabric ports in an equal fashion. However, if a fabric port goes down, all the FEX interfaces associated with that fabric port are down.
In this scenario, two individual switch ports, Ethernet 2/1 and Ethernet 2/2, are displayed in the up and active states in the output of the show fex 100 command. However, only one of those ports can be the fabric port because the pinning max-links command is configured to its default value of 1. In order to support more than one fabric port, you should issue the pinning max-links maximum-links command, where maximum-links is equal to the number of connected switch ports that should be used as fabric ports.
It is not likely that the switch is connected to the Cisco FEX by using a port channel. A port channel configuration bypasses the static pinning issue of a single interface taking down all the ports on a FEX because a port channel is a logical interface that is comprised of a number of physical ports. When a FEX is associated with a port channel instead of static pinning, a failed interface means that the other interfaces in the port channel take over for the port that is down.
It is not likely that the fex associate 100 command has been issued on the Po100 interface in this scenario. In addition, it is not likely that the port-channel configuration has not been completed, because there is no evidence of the configuration of a P0100 interface in the output. 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.