So, my background in networking has been largely Cisco Technology, and since starting here at ComputerWorld, I have been introduced to Dell Networking and have been learning the differences between Cisco and Dell. So, I thought it be useful to write about some of the useful CLI commands on Dell’s OS9 (S & Z series) switch OS that I have picked up and how they compare to the Cisco IOS commands that people might be more familiar with.
Creating an Access port
One of the first things any network engineer needs to do is configure an interface as an access port on a certain VLAN. Dell OS9 has taken a slightly different approach to achieve this. So, in the next section, I will go through setting up an interface as an access port and then how to make it a trunk. In this example, I will use VLAN 100. The first thing we must do is create the VLAN.
Cisco
Dell OS9
As you can see creating VLANs on Dell OS9 and Cisco are very similar, and if you know the commands for one, the other will be easy to pick up. The next step will be to assign the VLAN to the port or as dell does it assign the interface to the VLAN.
Cisco
In Cisco IOS we set the port to be an access interface and then with assign VLAN 100 to that interface under the interface.
Dell OS9
Unlike Cisco IOS you must set the interface to a switchport then under the VLAN set the interface to untagged. This is a different approach to how you assign VLANs to interfaces. It is like the way HP handles VLAN assignment. You will also notice that we had to do the command no shutdown on the interface. This is because on OS9 all ports are shutdown by default whereas Cisco they are all un-shut on their switches.
The key networking ideological difference between Cisco IOS and Dell Networking is that on Cisco a trunk port passes all the VLANs on that switch by default and you will then have to restrict the port if you need to restrict VLANs passing on a trunk port. The Dell approach is that this inherently insecure as you can by mistake have VLANs traversing your network that don’t need too and potentially add unnecessary congestion on the network. So, with Dell’s VLAN first approach you have to specify on each VLAN each interface you want to be allowed on that trunk port. It is a longer process config a trunk but a more secure approach than Cisco’s. As you must specify which VLANs are on the interface rather then cisco passing all VLANs by default.
Creating a Trunk Port
In the next section, I will through another fundamental function for a network engineer, creating a Trunk port on both Cisco and Dell OS9
Cisco
you then add in the command switchport trunk allowed VLAN to lock down the trunk interface to only VLAN 1, and 100 passing through this interface.
Dell OS9
On Dell OS9 you will create a trunk with the following commands.
Spanning tree The next and final commands I will talk about is configuring Spanning tree and the different show commands needed to check that your Spanning tree configuration. Cisco
The show spanning-tree summary command shows you on Cisco what version of spanning tree is running on the switch. By Default Cisco runs PVST (Per VLAN Spanning tree) and it is switched on. Dell by default does not run any form of spanning-tree. This is a very important thing to notice, and when configuring OS9, you must enable some form of Spanning tree. The following is the show commands for the dell.
Dell OS9
If you run this command and it does not return anything, then PVST is not running and needs enabling. I will next show how to enable PVST on both Cisco and Dell to illustrate the difference between them.
On the dell it is
The key thing for me to remember when configuring spanning tree on the Dells is the command “protocol” before spanning tree. It took me a little reading to find this command.
In summary, the key differences between Dell and Cisco are the approach they take to where the untagging and tagging happens (Cisco: interface, Dell: VLAN), how the trunks allow VLANs and how dell OS9 does not have any form of Spanning tree by default. But other than that the CLI commands are very similar and any engineer familiar with Cisco will no problem using Dell OS9.