You are currently viewing an archival version of GF!

Click here to return to the current GamesFirst! website.

Questions? Suggestions? Comments?
Contact us at:

Compex PS2216 Switch

star06.gif (4104 bytes)star06.gif (4104 bytes)star06.gif (4104 bytes)star06.gif (4104 bytes)

by Compex

Recently, I had a chance to sit down with Compex’s new switch, the PS2216, which is geared toward SOHO and gamer networks. With a data buffer of 128K, an 8K address table, and a backplane capacity of 3.2Gps, the switch compares to some of the higher priced SOHO switches and gives you some interesting features to boot.

Essentially, switching is the process of transferring data from one input interface to an output interface. A switch maintains a destination address and port number in its routing table (this is where that 8K comes in). When it receives a packet, it pulls in the header and extracts the source and destination and creates a temporary connection between the two, passes the packet, and then closes the connection, instead of repeating the packet to all ports increasing congestion as would happen on a HUB. The PS2216 uses the standard "store and forward" switching method, which basically means the switch will wait until it has the entire packet. Once it does, it will move the packet into its buffer, calculate its CRC value, and compare that value to the packet’s CRC. If the two match, then the packet is passed, if not, it is dropped. This method ensures packets are reliably transferred, but can increase latency. Other methods would include "cut-through", which means the switch will begin to forward the packet once it has the first 6 bytes, and "fragment-free", which means the switch will begin to forward the packet once it has received the first 64 bytes, since packet corruption is usually detected within the first 64 bytes. For all intent and purposes, the "stop and forward" method is fine for the PS2216 as it is the safest method and probably the best choice for the home user who doesn’t necessarily need to know much about networking, only that the device works or doesn’t work. And the PS2216 works nicely.

Configuration of the switch was easy, involving some quick evaluations of which features I would want enabled—those being: port trunking, port priority, and VLAN (Virtual LAN). Now, depending on how you look at it, the fact that configuration is done via dip switches rather than through an OS could be beneficial to the home user. There’s no need to deal with any on-board OS, like you would with a more intricate switch. The only downfall is that you’re unable to remotely manage the feature set. But, really, how many times would you be climbing under your desk to turn on or off a given feature? These decisions are usually made at the time of install or when you bring in another workstation.

Since management is done by dip switch, the switch has the hard-coded values for which ports will be assigned to a given feature and how the network is laid out. For an example, if you were to enable the VLAN feature, then all ports would be segmented into their own private VLAN, meaning one port couldn’t communicate with the other, leaving port 1 as the overlapping port. There’s no way for you to configure VLANs based upon what ports you would like to have in the VLAN, meaning you couldn’t have two VLANs, one with ports 2 – 8 and the other with ports 9 – 16. To the idle LAN bash, I don’t see this feature as being of real use; the Compex VLAN implementation would work better within a SOHO network. It would have been useful, if you could configure VLANs and assign ports to those VLANs instead of a single sweeping configuration.

Just like the VLAN feature, when you enable port trunking it is enabled for a certain set of ports; however, in this case, you have two groups, ports 1, 2, 9 and 10 or ports 3, 4, 11, and 12, leaving you eight additional ports free for other uses, two of which can become priority ports. Port trunking would come in handy if you had a box on the network that was pushing excessive amounts of traffic and you needed to increase its throughput. Essentially, you’re taking the ports and tying them together as a single port. The ports would, with full-duplex and 100-mbit speeds, give you around 800-mbit in speed. You could also connect two PS2216s together and use trunking to increase throughput between the two switches. Out of the entire feature set, this is probably the most useful, as it allows you to increase the bandwidth of a given machine on the local network. This would also be useful if you had some type of media or file server on your network that was pushing more traffic than other machines. To get this working wasn’t too difficult, and like everything else, it worked without error in my testing.

Another nice feature included of the PS2216 is the ability to prioritize ports, in this case 8 and 16. This is a way to assign packets higher priority over others. The packet with the higher priority is sent before the ones with lower priorities—very useful when you have a gaming server or another server that could require a higher communication priority. With this feature enabled, you don’t see too much, if any, degradation in performance.

It seems Compex laid out the features in a nice, easy way, where you could not only turn on trunking, but port priority. The only downfall here is you can’t combine the two. By this I mean you couldn’t trunk ports together and drop a router on the trunk and then assign a higher priority to that trunked, logical interface. But, in reality, most home users wouldn’t need this ability.

Overall, the PS2216 is a nice switch to work with. During my entire testing, I didn’t really get hung up with any of the features. The only downfall is that you’re not able to select which ports get what feature: they’re hard set by the manufacturer. Other than that, the switch performed under normal usage, as well as during LAN gaming sessions, without error and no noticeable latency. Combined with the low price-point of $60–65 (the lowest I found on and the feature set, this is a good switch for the average network user. Granted, I wasn’t able to push all ports to their maximum capacity to determine if I’d experience any strange issues, but during normal usage, the switch was flawless.

Matt Baldwin   (05/14/2003)


Ups: Easy installation; great price; reliable performance.

Downs: Easy use means fewer manual configuration options.

Platform: all networks