Virtual Link Trunking (VLT) may be used for connecting top-of-rack (ToR) switches or leaf switches in a leaf-spine topology. It offers end devices (such as servers) a redundant, load-balancing connection to the core-network in a loop-free environment. The VLT Interconnect (VLTi) is the physical link (cables and ports) used to form the VLT domain between the pair of switches.
The commands below setup a VLTi using ports 25 and 26 on each switch. For backup destination, use the IP address of the management interface of the VLT peer switch.
Note: Use the show vlt 1 command to verify VLTi link is up. Use the show vlt 1 backup-link to verify Peer Heartbeat is up.
To take advantage of VLT, a minimum of one port from each switch must be paired into a VLT port channel for each device being attached, so they can connect to both switches. The following figure shows two such devices.
The commands below allow for the two devices to be attached, each connecting to its own VLT port channel. More VLT port channels would allow for attaching extra devices.
Configure ports to attach end devices (switch #1)
Configure ports to attach end-device (switch #2)
OS10(conf)#interface range eth 1/1/1-1/1/2 OS10(conf-range-eth1/1/1-1/1/2)#switchport access vlan 10 OS10(conf-range-eth1/1/1-1/1/2)#no shutdown OS10(conf-range-eth1/1/1-1/1/2)#exit
OS10(conf)#interface port-channel 1 OS10(conf-if-po-1)#description “Device 1” OS10(conf-if-po-1)#switchport access vlan 10 OS10(conf-if-po-1)#vlt-port-channel 1 OS10(conf-if-po-1)#spanning-tree port type edge
OS10(conf-if-po-1)#interface port-channel 2 OS10(conf-if-po-2)#description “Device 2” OS10(conf-if-po-2)#switchport access vlan 10 OS10(conf-if-po-2)#vlt-port-channel 2 OS10(conf-if-po-2)#spanning-tree port type edge
OS10(conf)#interface range eth 1/1/1-1/1/2 OS10(conf-range-eth1/1/1-1/1/2)#switchport access vlan 10 OS10(conf-range-eth1/1/1-1/1/2)#no shutdown OS10(conf-range-eth1/1/1-1/1/2)#exit
OS10(conf)#interface port-channel 1 OS10(conf-if-po-1)#description “Device 1” OS10(conf-if-po-1)#switchport access vlan 10 OS10(conf-if-po-1)#vlt-port-channel 1 OS10(conf-if-po-1)#spanning-tree port type edge
OS10(conf-if-po-1)#interface port-channel 2 OS10(conf-if-po-2)#description “Device 2” OS10(conf-if-po-2)#switchport access vlan 10 OS10(conf-if-po-2)#vlt-port-channel 2 OS10(conf-if-po-2)#spanning-tree port type edge