Last Updated on August 2, 2021 by Admin 2
You issue the following commands on SwitchA and SwitchB, which are Cisco Nexus 7000 Series switches:
SwitchA(config)#vpc domain 101 SwitchA(config-vpc-domain)#peer-keepalive destination 192.168.1.2 source 192.168.1.1 vrf default SwitchA(config-vpc-domain)#exit SwitchA(config)#interface range ethernet 2/1 - 2 SwitchA(config-if-range)#switchport SwitchA(config-if-range)#channel-group 1 mode active SwitchA(config-if-range)#interface port-channel 1 SwitchA(config-if)#switchport mode trunk SwitchA(config-if)#vpc peer-link SwitchB(config)#vpc domain 101 SwitchB(config-vpc-domain)#peer-keepalive destination 192.168.1.1 source 192.168.1.2 vrf default SwitchB(config-vpc-domain)#exit SwitchB(config)#interface range ethernet 2/1 - 2 SwitchB(config-if-range)#switchport SwitchB(config-if-range)#channel-group 1 mode active SwitchB(config-if-range)#interface port-channel 1 SwitchB(config-if)#switchport mode access SwitchB(config-if)#vpc peer-link
Which of the following is most likely a problem with this configuration?
- The Ethernet port range is using the wrong channel group mode on SwitchB.
- The vPC domain ID on SwitchB should not be the same as the value on SwitchA.
- Port-channel 1 on both switches should be a trunk port.
- Port-channel 1 on both switches should be an access port.
- The vpc peer-link command should be issued only on SwitchA.
Most likely, the problem with the configuration in this scenario is that Port-channel 1 on both switches should be a trunk port, not just the configuration on SwitchA. Trunk ports are used to carry traffic from multiple virtual local area networks (VLANs) across physical switches. Access ports can only carry data from a single VLAN and are typically connected to end devices, such as hosts or servers. To configure a virtual port channel (vPC) domain between two switches, you should first enable the vPC feature, then configure the vPC domain and peer keepalive links. Next, you should configure 10-gigabit-per-second (Gbps) links between the switches as members of a port channel and configure that port channel as a trunk link. Finally, you should configure the port channel on each switch as a vPC peer link.
The vPC domain ID on SwitchB should be the same as the value on SwitchA. A vPC domain is comprised of two switches per domain. Each switch in the vPC domain must be configured with the same vPC domain ID. To enable vPC configuration on a Cisco Nexus 7000 Series switch, you should issue the feature vpc command on both switches. To assign the vPC domain ID, you should issue the vpc domain domain-id command, where domain-id is an integer in the range from 1 through 1000, in global configuration mode. For example, issuing the vpc domain 101 command on a Cisco Nexus 7000 Series switch configures the switch with a vPC domain ID of 101.
The vpc peer-link command should be issued on both switches in this scenario. A vPC peer link should always be comprised of 10-Gbps Ethernet ports. Peer links are configured as a port channel between the two members of the vPC domain. You should configure vPC peer links after you have successfully configured a peer keepalive link. Cisco recommends connecting two 10-Gbps Ethernet ports from two different input/output (I/O) modules. To configure a peer link, you should issue the vpc peer-link command in interface configuration mode. For example, the following commands configure a peer link on Port-channel 1:
SwitchA(config)#interface port-channel 1 SwitchA(config-if)#switchport mode trunk SwitchA(config-if)#vpc peer-link SwitchB(config)#interface port-channel 1 SwitchB(config-if)#switchport mode trunk SwitchB(config-if)#vpc peer-link
It is not a problem that the channel group mode is configured to active on the Ethernet ports in this scenario. It is important to issue the correct channel-group commands on a port channel’s member ports prior to configuring the port channel. For example, if you are creating Port-channel 1 by using the Ethernet 2/1 and Ethernet 2/2 interfaces, you could issue the following commands on each switch to correctly configure those interfaces as members of the port channel:
SwitchA(config)#interface range ethernet 2/1 - 2 SwitchA(config-if-range)#switchport SwitchA(config-if-range)#channel-group 1 mode active SwitchB(config)#interface range ethernet 2/1 - 2 SwitchB(config-if-range)#switchport SwitchB(config-if-range)#channel-group 1 mode active