Tech Flashback: Ethernet Hubs & Switches (Netgear DS104 & Skymaster 8320-030)

Ethernet has been around for so many years that we hardly ever take the time to stop and think about it. We take it for granted that most desktop PCs come with Ethernet ports integrated on-board, Ethernet switches are cheap and plentiful and most devices are “plug and play” with auto-negotiation of duplex and speeds. In fact, nowadays, we could probably say the same about Wi-Fi.

Of course, this wasn’t always the case but it wasn’t something I actively thought about until last week when I dropped into the university and was handed a “deadNetgear DS104 dual-speed Ethernet hub.

As a result, this post is a bit of a mix of a tech flashback reminiscing about old technology, teardown examining the insides of these devices and a repair where I get them back to functionality.

Before Ethernet, there was … serial?

While regular 10Mbit/s Ethernet was standardised in 1983 and 100Mbit/s Fast Ethernet in 1995, it wasn’t something I personally had access to until much later. For most homes and even at school, Ethernet wasn’t cost-effective as NICs, hubs and cables were not inexpensive. Part of the reason for this was the computers themselves, which had limited processing power and memory, requiring the NICs to be more complex and “intelligent” to keep networking performance high without overburdening the CPU. That being said, Ethernet still had an advantage of being vendor-neutral which helped drive costs down steadily through competition.

As a result, most computers even up to the late 90’s did not come with Ethernet as standard. While USB was released in 1996, it wasn’t until USB 1.1 in 1998 until it started to take off. As a result, what we were left with were the parallel and serial ports. On the PC, under Windows 9x, one could use null-modem cables with the serial ports to do a direct-cable connection for file/printer sharing. This wasn’t particularly fast, as most regular 16550 UARTs of the days managed 115,200bps at the most, but if you were stuck with an 8250, then 19,200bps was more realistic. A faster method was to use parallel ports with a “Laplink” cable, which was able to transfer data quicker but at the expense of high CPU usage and not being able to use a printer without adding another parallel port.

On the Mac side, serial-based networking was even more developed. When I was in Year 4 (1998) in primary school, I was already helping them maintain their Appletalk network. It was then that I saw a real RS-422-based multi-drop bus network that seemed to work even faster than the null-modem cables I had been playing with. Then, I found that the library was running Appletalk over phone lines using a clone of the PhoneNet adapter and this set off a light-bulb moment.

As 30m of phone line can be had from variety stores relatively cheaply, I decided to use it as my networking medium. Thanks to some generosity, I managed to get a pair of V.90 modems practically for free. I connected them back-to-back in a dry-loop configuration to try and make a connection. As it turns out, Windows 9x didn’t like to “connect” unless the phone line rang, so I hooked 24V AC from a transformer over the tip-ring pair momentarily to cause the other end to pick up. Unfortunately, the end-to-end connect rate was only 33.6kbit/s symmetrical. I didn’t understand why at the time, but seeing now that I understand how V.90 works, getting 56kbit/s was just a dream anyway.

By then, I was about to graduate from primary school in Year 6 (2000) when my passion for electronics collided with the purchase of my first soldering iron and a few visits to Dick Smith Electronics. I wanted to network a computer upstairs with my main desktop downstairs – a distance of 30 meters, but nobody made null-modem cables that long. Worse, if I had to pay full price for RS-232 extension cables, I’d be sent broke as a primary school kid with an allowance of about $5 a week …

That’s when I put two and two together and built these adapters. I found the serial pin-outs for a null-modem cable with “loopback” handshaking (i.e. no hardware flow control ability) and figured that we really only need three lines to carry data bidirectionally – RXD, TXD and Ground. I hacked apart a few modular-to-605 adapters to grab the modular jacks to break out the wires. I realised the order of the wires “roll over” from end to end on flat cord, so I swapped the order on the other side to match. Not wanting to spend any additional cents, I didn’t order any back-shells to the connectors.

Not having much in stock at the time, I took the jumper wire from an old dead Philips CRT that had solid-core wire between modules. This was almost my first attempt at soldering and I’d have to say that I absolutely butchered it. Melting the plastic formers, overheating the pins, cold joints, too much solder on some pins and solder not wetting wires are amongst the problems. But I had a multimeter and continuity was still there where it mattered.

Despite not knowing anything about electronics, I plugged it in and it miraculously worked and became the home network for about three and a half years. It ran at 115,200bps, but due to overheads and retransmissions, a file copy would take about three minutes to transfer 1MiB or about 45kbit/s effective. That was much better than the modem solution which was only about half this.

Knowing what I know now, this was a rather happy-go-lucky moment, as the capacitance of 30m of phone line could well have stressed the RS-232 drivers enough to eventually cause damage or enough data errors to render it unusable. It just so happens that it worked and when I rediscovered the pair of adapters during a clean-up, it bought back some happy memories.

Netgear DS104 4-port Dual-Speed Ethernet Hub

In the 2018 world of full-duplex Gigabit Ethernet and emerging affordable 10GbE solutions, it seems that gear that keeps working is often kept employed until it fails outright. I was rather surprised when, at the university, I was presented this dead Netgear DS104 4-port dual-speed Ethernet hub.

While not as elderly as the “single speed” hubs like the Synoptics Lattishub 2803 I had, it still deserves a mention for a number of reasons. The first is that Bay Networks logo – for a moment in history, Bay Networks (formed from the merger of Synoptics and Wellfleet) was big news in the networking market commanding up to 20% market share of network routers worldwide. They were eventually bought by Nortel and in 1996, began to spread into consumer market under the recognisable name of Netgear.

I’m almost certain that this particular model made it to my primary school in 2000, as the year I graduated was the year they upgraded to Fast Ethernet and the IT lady started to scatter these about in the school – one per classroom. The main attraction of the box was the vast array of LEDs which blinked almost hypnotically – this includes a network utilisation indicator on the left, as well as “vista” LEDs which indicate link/activity. The last port has a normal/uplink switch for controlling cross-over – needed in the early days prior to MDI/MDI-X auto-switching ports, especially if you were connecting hub-to-hub with a straight-through cable.

The other reason this particular unit is so memorable is the metal casing, bold colourful text on the top and blue colour. This almost became a standard – desktop metal-chassis-based networking equipment often was blue probably to “capitalise” on the goodwill surrounding Netgear equipment (which was, at the time, quite strong from what I recall). The sides of this unit had no openings at all.

The underside has a model compliance label, rubber feet to stop it sliding around on a desk and some wall-mounting holes. These were used in the school to keep it away from prying kids fingers.

The rear has two screws to hold the unit together, a grounding screw with tag and an input for 5V DC at 3A. This contrasts with most of the documentation which still resides online which claim this unit uses a 12V power supply.

The unit was supplied with a switching power adapter which connects to an IEC cable. A quick test showed the unit to have failed, with no power output. Opening up the adapter by undoing a hidden screw revealed that the power adapter has suffered something catastrophic.

The fuse is sooty towards the bottom and has opened. A quick check shows both primary side transistors have gone dead-short through all three pins, which is bad news. Being a 5V appliance, I couldn’t be bothered to repair the supply – it’s old enough that there might need to be more components replaced due to accumulated heat damage over time.

Instead, I tested the unit on a lab benchtop supply and found it to be working just fine. Luckily it seems that any transient which may have happened when the power supply failed didn’t overstress anything. The unit established link on all ports just fine – but the uplink switchable port seemed to be slightly intermittent due to an intermittent switch. Port 2 is connected to an old 10Mbit/s device for demonstration purposes and also establishes link correctly.

As a result, I made a quick lead that goes from USB to the power cable – now I can power it from any USB wall supply or power bank. It doesn’t actually draw 3A – under harsh testing, I only got the current consumption up to about 1.8A.

Most of the time, obsolete equipment is just that – obsolete. Destined for the trash, perhaps. But this one was interesting enough that I wanted to preserve it. Before the days of affordable network switches, hubs were the way you would get multiple computers connected to the network. These devices operated at one speed and half-duplex, receiving a signal from one port and transmitting it out of all the other ports simultaneously. This kept costs low, as there wasn’t much smarts necessary to do this.

But this was limiting performance-wise as now all ports attached to the hub (and to the hubs cascaded from it) are considered a single collision domain. As a result, only one machine in the whole collision domain can be using the media at any time – the larger the network, the more likely collision-induced degradation of network performance might be encountered. This also imposed a limit to the depth of the cascading of hubs due to the propagation delay – a jam signal is sent when a frame collision is detected to “clear” the medium and in order to ensure all collisions are detected, cascading of hubs was limited to about three levels to ensure it worked correctly. Finally, in most hubs, all ports operated at the same speed.

The DS104 occupied a short span in time where Fast Ethernet was becoming more popular but Ethernet devices were still plentiful. Users looking to “migrate” or “mix” would usually have to opt for an Ethernet switch which was a lot more expensive. This resulted in a short period where dual-speed hubs existed – this can be thought of as a “combination” 100Mbit/s and 10Mbit/s hub with a bridge (or two port switch – one in each speed) between the two that only forwards the frames required. As a result, it’s possible to send data into the 10Mbit/s section from the 100Mbit/s section and saturate the 10Mbit/s portion while being able to use the surplus bandwidth to communicate with other 100Mbit/s stations. Neat! You don’t see LED indicators like this nowadays – back then, there were also CPU indicators for smart-switches.

Taking a look inside, it seems that the unit is probably dated Week 26 of 1999 based on the (relatively mysterious) Delta DH-5C008 chip and the magnetic transformers. It seems the logic operates at 3.3V with a linear regulator on the left side. The main chipset is heat-sinked – I didn’t remove the heatsink to find out what it is because I doubt I’d find anything about it.

The magnetics come from Delta as well. Towards the front is an Etrontech memory of some sort – thus I suspect the DH-5C008 is a “dual-speed-hub” chip that does the bridging function. The other may be a conventional 100Mbit/s hub chip.

Even at this time, we can see the relatively questionable G-Luxon branded capacitors appearing. Eugh. At least the input is filtered and protected by a polyfuse.

It seems like some of these things really do keep trucking along – Erik Erckel of TechRepublic wrote back in 2008 about cracking open his DS104 – this one appears to be a later model with component dates of Week 22, Year 2000. Key differences include running from 12V DC with a different internal set of chips.

Skymaster 5-port Fast Ethernet Switch

The landscape was quickly changing, however, as Fast Ethernet saw the democratisation of networking for home users. Low-cost chipsets from Realtek really drove prices through the floor and made 100Mbit/s a possibility, even though it meant using more CPU than with higher-end solutions.

The phone line solution I mentioned earlier served me well, but the speeds were frustratingly slow. It proved the utility of a home network, so I decided to start an Ethernet one of my own. By the time I was in Year 9 (2003), I had an old second-hand machine with a 10Mbit/s Ethernet card already installed and was about to buy a new machine with 100Mbit/s Ethernet inbuilt. My Dad also had a machine with a few free PCI slots and Realtek “crab” cards were not expensive. My brother inherited another old machine, without any free slots, so an ADMtek USB 1.1 Ethernet adapter (slow…) was the solution there. We finally had “regular” dial-up internet access, so it made sense to share it. All this necessitated a network switch.

At this time, a friend from high school had just gotten a cable broadband connected and wanted to share it too. He purchased a switch, not knowing that he actually needed a router and ended up selling the unit to me for AU$40. Compared to prices only a few years earlier, this was a bargain, although the first unit he supplied was faulty and was RMA’d for this second unit.

Compared to the Netgear, this is the full fat solution – physically compact, one more port, switched so no “flooding” the network with packets, ability to work mixed speeds and duplex and automatic cross-over on all ports. This is very much everything you would need for a small home network in the early 2000s.

Having LEDs on the front and ports on the rear makes for a neater and possibly cheaper solution too. The unit accepts 9V DC.

The unit has ventilation holes on both sides, which is probably unnecessary, but a nice feature. Also notice that it’s a very similar blue to the Netgear switch … I don’t think that’s a coincidence.

Despite that, there’s no branding on the top. Skymaster is really just an import-and-rebadge operation anyway, so it’s probably as generic as it gets.

A look on the underside shows that the unit is dated Quarter 1 of 2003. I labelled it with my name and address (blanked for privacy) – it was that important to me at the time.

The power adapter was also extremely generic but the unit has been very reliable. The label has crazed due to the accumulated heat damage, but the unit was still functional in 2018. The one thing that happened was that the unit started to make hissing noises, which seems to be a key indicator that capacitors were going bad.

As a result, I cracked it open for a repair. Inside, the case has a firm date of 19th February 2003.

Rather unsurprisingly, the switch is a “one chip” solution from Realtek, a RTL8305SB. This picture was taken after a kludge capacitor replacement – using any spare caps I had on hand with a similar value from Panasonic, Rubycon and even a tantalum. At times, I replaced parallel pairs of capacitors with a single one too – I just wanted to revive the unit to a reliable non-hissing state.

That did the trick. In the top case, I have it hooked into the DS104, on port 1, confirming the half-duplex nature of the hub. The bottom shows three ports – two full-duplex and one 10Mbit/s half-duplex. Speeds are not indicated by the LEDs.

While the amount of time and money spent on the capacitors were probably not worth it economically speaking, I repaired the unit out of pure sentimentality. To think this is the first incarnation of Ethernet at my house and that it still works is pretty amazing considering the 15-years that have passed. A new unit would be faster (GbE), cheaper (~$19), more reliable and more energy efficient (EEE), however.

Conclusion

Ethernet’s ubiquity and low cost makes it an important part of most home networks today. Coming standard on most desktop computers, test equipment and even some consumer electronics appliances, it’s pretty much plug and play, offering a decent amount of bandwidth over cheap twisted pair cable.

From humble 10Mbit/s business-oriented beginnings, it became economical towards the middle of the 100Mbit/s Fast Ethernet era, becoming ubiquitous in the home. With the rise of the internet, broadband connectivity and network sharing, 1Gbit/s is commonplace and cheap 10Gbit/s solutions are on the horizon.

It’s fascinating to see how quickly, in the space of a few years, switches displaced hubs from the market and rendered issues of speed, duplex, collision domains and hub cascading moot. It’s also equally fascinating to see some of this old equipment still running until it fails. Even when it does, it’s sometimes a trivial fix, which means that you can just keep it going (provided the performance is sufficient and power use is not unacceptable). It wasn’t so many years ago that I saw a Racal InterLAN Repeater hanging off a wall above a doorway that was still powered, despite no thin-net clients having been connected for a decade.

Random Bonus

A month ago, heading home from some part-time work, I was in a train, headed towards Schofields. The train line runs parallel to the new developments of Akuna Vista and The Altrove, where a lot of land has been released and is in the process of being developed. It was a chance encounter that it was a bright and sunny day and I was looking out the window of the mostly empty train at the earthmoving equipment kicking up plumes of dust.

Realising the artistic nature of that moment, I snapped a quick photo with my phone and did some perspective corrections and curves alteration. The limited dynamic range makes the image somewhat reminiscient of a old Kodachrome/Ektachrome slide, especially with the rounded corners of the train windows framing the shot and adding a slight vignetting. Just thought I’d share … after all, slides and photographic film it reminds me of are vintage technology as well :).

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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4 Responses to Tech Flashback: Ethernet Hubs & Switches (Netgear DS104 & Skymaster 8320-030)

  1. Tesla1856 says:

    With the Netgear DS104 4-port Hub, looks like you got a free working one. Yes, I still buy Netgear, but my experience is about the same with their Desktop Ethernet Switches. After about 4 years, their cheap/tiny (under-rated ?) AC-Adapters (SMPS) fail. They fail strangely … like not enough amps under load, or start outputting only half of rated voltage. Luckily, they are easy enough to swap-out.

  2. sparcie says:

    Nice to see some cool old gear. I have a similar 100Mbit/s network switch still in service and on old 10Mbit/s 5 port hub that’s a skymaster as well. I should really get around to replacing the old switch!

    Ethernet is quite interesting as a standard. We’re all used to seeing it with the now familiar blue cables. But in it’s early days it was actually typically run using a single run of coaxial cable, each node connected in either using a T piece or tapped directly into the cable. I remember seeing coax running around the mathematics building when I first came to uni as a student. I also used it for the first network I set up, as hubs and switches were both expensive. By using coax I only needed the NICs and cabling, which turned out much cheaper.

    I believe that ethernet was originally developed at Xerox PARC before being spun off into it’s own company 3com, who went about making it a common open standard. The Xerox Alto (and later machines) had early ethernet NICs.

  3. I was not prepared for the feeling of nostalgia seeing that DS104! Many many lan parties were had with a few of those chained together! A friend had acquired a DEC Alpha from a closing business which made an excellent dedicated QuakeWorld server.

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