PS2216 -- Specifications and Installation
Specifications
¨ Industrial Standards: Complies with IEEE 802.3 10BASE-T, IEEE 802.3u 100BASE-TX and ANSI/IEEE 802.3 N-Way auto-negotiation standards.
¨ Interface: Each unit has 16 10/100Mbps UTP ports (RJ-45), with pretty LED's indicating link activity and speed (green: 100Mbps; amber: 10Mbps)
¨ Switching Buffer: 128K bytes
¨ Forwarding Method: Store-and-Forward
¨ Number of MAC Addresses: 8K MAC Addresses
¨ Dynamic Addresses, Learning/Filtering: Yes
¨ Power Supply: External 3.3VDC, 3A
¨ Physical Dimensions: 151 x 92 x 35mm (L x W x H)
¨ Weight: about 0.26kg
The PS2216 implements a switching strategy called Store-and-Forward. It's the slowest of the three (Cut-Through and Fragment Free are the other two), where it copies an entire frame into its buffer and computes a CRC. This causes higher latency. It then looks up the destination address in its switching table and figures out which port to send it out, and finally, sends it out.
In case if you're wondering, Cut-Through is the fastest, trading speed for error checking.
There is also a little LED on the box labeled 'Flow Control' which apparently won't light up during use. As the internals of switches get faster and faster, flow control isn't used much or even necessary, so it's understandable. Basically if a server starts slinging packets faster than the switch's input buffer can handle, the switch will send the server a 'choke' packet. There's more to it than that, but that's the simple description. Most switches are output buffer oriented, just for the speed of it, so once a packet goes through the crossbar, the switch can't tell which port sent it to shut it up. So the PS2216 might have flow control built-in, but you'll never see it work.
Installation
The PS2216 has a very nice auto-negotiation feature. It didn't matter what type of cable that we plugged into it, be it cross-over or straight-through, or what port you plug into it, it will figure it out and just work. This is a nice touch because invariably you discover that you need a different cable very late at night.
To its credit, Compex included a handy Quick Install Guide. In just about every language imaginable. One side I was reading English and the next it was Cyrillic. The QIG has a 4-step installation procedure, 5 if you hang the switch on a wall. Let me run you through them! I'm kidding. It is the standard, unpack and plug it in and watch the LEDs light up, variety. Woops, I guess I just ran you through it. You can get your money back at the top of the page. No, I'm kidding again. We're keeping all the money.
We did find the review PS2216 had a flimsy power connector. If you bump it accidentally, it will cause a restart of the switch. I'm wondering why Compex didn't use a standard size power plug. The wall wart only got medium warm during use, which is a Good Thing.
