NETGEAR GS110T Technology Details
I did not remove the heatsink from the switching IC, fearing that I would damage it in the process. The lack of any hardware holding it in place intimates that the thermal paste in use is that hard, plastic-like material that cures in place. That stuff can be hard as a rock and just as stubborn once it has set. But, I can almost guarantee that the switching chip is made by Broadcom, and judging from the 8+2 port layout, it’s probably the BCM53312. This 8-Port GbE + 4-Port GbE Multilayer Switch is one of the most highly integrated switches that Broadcom produces, which explains the minimal number of support chips on this PCB. Since the CPU and the Gigabit PHY functions are built in, there’s very little that needs to be added to the BCM53312 in order to build a functioning network switch. The fact that it can do all this with passive cooling is a bonus.
The Flash memory that stores all the configuration data, is provided by Marconix, and is a 128MB model with the basic designation of MX29GL. It is a high performance version, with page mode read access. Later in the article we’ll look at all the configuration options that are available on the NETGEAR ProSafe products, including this GS110T, and the need for fast read/write access to the Flash memory will become more obvious. The embedded web server runs from this storage space as well, so this component does get a workout while the SmartSwitch features are in use.
The Switching module and the integrated CPU both need access to some basic DRAM in order to do their jobs. In the GS110T, NANYA provides a single DDR400 chip, which has an overall capacity of 512MB, in a 32M x 16 arrangement. The specs from NETGEAR only specify 64 MB of SDRAM for this model, but perhaps that is all that is used for this application, even though more is physically available on the chip.
With high speed serial data transmission, cable performance is an important component of reliable operation. Equally important is the impedance that the active devices present at the connector body. One of the best ways to get this critical interface right is to use transformers, a seemingly ancient technology, that somehow hasn’t been replaced with silicon yet. There are four FPE H40520MN quad transformer modules sitting between the Broadcom switch IC and the 1000BASE-T connectors on the front panel that perform this important function.
The construction quality was top notch, throughout the GS110T, even down to the manufacturing processes used on the printed circuit board. Directly below the main IC on the board, there are over a hundred very small SMD components that are difficult to see clearly with the naked eye. The wave soldering process looks excellent here, and throughout the board. Plus, this is one of the cleanest PCBs I’ve seen in awhile. No fuzzy bits, no funky residues, no discolorations, no excess adhesives, nothing that would detract from the long term reliability of the system. Reliability is the key word here; the customers who routinely buy this class of switch are building networks for people and companies that use them for profit, not for fun. If they stop working, everyone stops working and the company loses money until it’s fixed.
Unless you want to start straining your eyeballs on block diagrams and logic/timing charts, that’s about as far as we can go on the hardware side. Let’s start digging into the features and specifications of the NETGEAR GS110T before we fire it up and see how the control software works.