Before we begin, it’s always a great idea to have a physical drawing or make a physical drawing based on information you eyeball or able to gather using show lldp neighbor commands. Below is a drawing I created, that I will be using for a guide. In this demonstration, we will be focused on the two switches connected to the VxRail. The port-channel information, shown below as “Po” is shorthand for port channel and can be any number between 1 and 128. The upstream port-channel doesn’t necessarily have to identified as the same port channel number. Port channel numbers are locally significant.
Login to the switch and run a few commands to get a general sense of the switch config.
Looking at the running config, i’m going to use some existing vlan’s as a template to make my new vlan’s.
S5248F-FR8U13-site2# show running-configuration
Taking some and copy into notepad to create your new VLAN’s. We will edit in notepad to create new VLAN’s to paste into the switch config. Below are the new VLAN’s I want to add (2641-2648). I give them some descriptions to better document how the VLAN will be consumed. Next week, I might forget and this will help me and other’s understand the topology.
From switch CLI enter into configuration terminal mode. Then copy from notepad into the switch console.
S5248F-FR8U13-site2# configure terminal
We set the MTU size, and did a no shut to make the VLAN active. We still need to configure the VLANs on the upstream port channel and the server facing ports.
To make things easy, I’m going to grab one of the ports that connected and configured already and use that to help me configure the interfaces.
Copy the output of the interface shown above and put in a text editor and add in our vlan’s 2641-2648.
Since we just want to update the vlan’s instead of copying the entire interface configuration, i’m just going to grap the switch port trunk allow vlan and paste that updated bit into my switch.
Run the show interface command again on the switch to verify which ports we want to update. We will run the updated VLAN command against ports eth 1/1/5 – 1/1/12 and again for 1/1/16 – 1/1/24 for consistency. One can argue it’s not needed on some of these ports, but I like consistency.
When in the switch cli you can often get more information about command structure by doing ‘tab’ ‘tab’ like below. I did switchport trunk allowed vlan ‘tab’ ‘tab’ or question mark ‘?’ to get more information on correct syntax. The ‘tab’ key will autocomplete any partial command you’ve typed and the question mark will give more details on the next option.
Let’s look at the interface status command again to verify VLANs are there.
Now we need to tag the upstream port channel. Find the port-channel and add those new VLANs to the port-channel. Below we see how this is done.
You might notice there’s two port channel’s port channel 44 and port channel 1000. I have previously configured VLT on these switches. If VLT is configured, the new VLANs will automatically be added to the VLT port channel, once both switches in the VLT pair have the vlan’s configured.
Once you are satisfied with your updates save the running config to the startup config
S5248F-FR8U13-site2# copy running-configuration startup-configuration
Now we need to exit out of this switch and login to the other switch in the VLT pair. If you don’t have a VLT pair, you should at least have a secondary switch so there’s no single point of failure. Typically there is always two switches for redundancy. Often we will say Top of Rack 1 and Top of Rack 2 and shorten that down to ToR-1 / ToR-2 when speaking. I like to give the switch a meaningful name that shows the Rack number and the U number in the rack. In this example, it’s Front Row rack 8 in U 12 / U 13.
We should still have the switch configuration in our notepad to easily update the secondary switch, ToR2, hostname: S5248-FR8U12-site2.
Above, I ran a few commands like show version, show vlan, show interface status to get a feel for the configuration. Let’s run configuration terminal to get into configuration mode and run the commands from notepad.
Update the server facing ports. If I just add the new VLANs it will not remove the existing VLANs. Notice this method is slightly different than I describe previously. Instead of listing out all existing VLANs, I just type the ones that I want to add.
Update the upstream port channel as well. Add VLAN 2641-2648 to port-channel 44. Your VLANs and port-channels may differ, as each environment is unique, but you get the idea. One call out, notice on the port-channel running configuration, there’s a parameter saying “vlt-port-channel 44”. Since the switches are in a VLT pair, this allows me to create a unified / single port-channel that spans both switches in the VLT pair. Note: There can only two switches in a VLT pair. Other use cases for VLT might be a server facing port channel. In my scenario, I have a VLT pair going upstream to a secondary pair of switches in a VLT pair. This allows me to have path redundancy and no single point of failure between two sets of switches.
Don’t forget to save the running configuration to the startup configuration.
S5248F-FR8U12-site2# copy running-configuration startup-configuration
We have successfully added the new vlan’s to the PowerSwitch S5248F-ON in a VLT pair.
To touch on the comment about the VLAN being automatically added to the VLTi port-channel, if we run show vlan again on either switch, after doing both sides we will see that the newly created vlan’s are added to the VLT port channel as below.
As a closing statement, the only thing left to do is make sure the VLANs exist on the upstream switches all the way to the core gateway / router. In some cases, the gateway / router might be on the local ToR’s or upsteam somewhere.