Switch usability centers on CLI comfort zone

Any assessment of switch usability is necessarily subjective. While there are some objective measures that can be applied (for example, it might take 17 steps to enable SSH on one switch, and only five on another), usability assessments ultimately come down to what's most comfortable for any particular user.

For most of the industry, "comfort" means a command-line interface (CLI) that either is or closely resembles Cisco IOS. It hasn't escaped the attention of Cisco competitors that more network engineers are trained in IOS than any other CLI.

In this test, the Dell, Foundry and HP CLIs were very IOS-like. HP's was probably the closest clone, with Foundry close behind (although both use slightly different syntax for referring to physical and virtual interfaces). The Dell CLI was inconsistent in a few places. For example, some commands refer to an interface with an "ethernet" prefix and others do not.

The Alcatel-Lucent, D-Link and Extreme switches use home-grown CLIs. Perhaps it's just our greater familiarity with it, but we found Extreme's XOS CLI by far the easiest of these to learn and navigate. It also offers some useful monitoring features we didn't see in other switches, such as the ability to monitor port statistics, even across multiple ports, in real time.

The CLI in Alcatel-Lucent's OmniSwitch saves configurations twice, in "working" and "certified" directories. This feature can be very useful in testing out new configurations, because it allows network managers to roll back to a known good configuration in case of error.

One aspect we didn't like in the OmniSwitch CLI: Unlike all other switches tested, it lacks the ability to execute the shortest unambiguous version of a command. So, for example, while most switches will happily understand that "sh run" is an abbreviation for "show running-configuration," the OmniSwitch instead complains unless it receives the longhand version of "show configuration active." The fact that the OmniSwitch has tab completion for commands is only partial compensation; switch configuration would run faster if the CLI accepted abbreviated commands, like all others.

The D-Link 3650's CLI configuration syntax is verbose, sometimes too much so. As with many other CLIs, typing the tab key will display options for how a command might be completed. Unlike all others, the switch places a full string on the command line, which the user must then erase. For example, typing "config vlan <tab>" places the string "config tab <vlan_name 32>" on the command line, and the user must then delete the string "<vlan_name 32>" before continuing. While it's useful to know a VLAN name can be 32 characters long, the need to erase strings got tiresome after a while.

We also did a quick review of vendors' documentation. While all documentation did an adequate job of describing the commands available on each switch, there were differences in explaining the basic technology behind each command, and why users would want to use (or not use) that technology. The Dell and D-Link documentation included relatively little in the way of technology background. Of the others, we considered the Cisco, Extreme, and Foundry documentation to offer the most complete technology tutorials. HP's documentation is also first-rate, but doesn't cover as many features as some of the other switches, especially for IP multicast.