FDDI to Fast Ethernet "Bridge" Available?

(Originally posted in comp.dcom.lans.fddi)

Hi there. I currently have a Synoptics FDDI workgroup concentrator, and I use a server as a FDDI-to-Ethernet router to connect to the Fast Ethernet switch and to my Wi-Fi access point. Is there such a thing as a standalone FDDI to Fast Ethernet "bridge" available, which uses less power than my server? I would like to decommission my old server with this network bridge.

Thanks in advanced.

P.S. The reason why I have the FDDI concentrator is that two years ago, a severe thunderstorm fried my telephone and computer equipment. This despite having a whole house surge protector, UPS, and end-point surge protectors (including for coax and telephone line). My electrical panel was replaced a few years ago and checked by a certified electrician (and inspected by the county inspector). So I am using the FDDI to isolate my computer equipment using fiber cables.

treet007 wrote: (snip)

Wouldn't fiber based ethernet also do that?

I would guess that both FDDI and fiber ethernet equipment is available used for reasonable prices, but the FDDI/Ethernet bridge might be hard to find on eBay. 10baseF (or FOIRL) should be pretty cheap (at 10Mb/s), 100baseFX is probably easier to find and just as affordable as the FDDI/Ethernet bridge.

-- glen

On Wed, 1 Oct 2008 20:38:19 -0700 (PDT), treet007 wrote: [google's original formatting left in]

I'm not aware of such a thing (but that doesn't mean they don't exist), and as noted for your purposes ethernet over fibre might work just as well. But switching does deprive you of your previous investment.

I'd like to add is that you could build yourself a lower-power version of an fddiethernet router using, eg. via epia/c3/c7 boards, or soekris or pcengines boards. All of them can run linux or one of the *BSDs, and most come with ethernet on board and one PCI slot. I recall seeing a two slot PCI riser board advertised as an accessoire for the epia boards.

It seems that there are PCI-X gigabit fiber (1000baseSX) cards on eBay for $23 (buy it now, $15, plus $8 shipping).

As I understand it, they will also work in PCI slots.

It sounds like you have all your machines on fiber, which is good but shouldn't be necessary. If you have the first device inside the house (DSL or cable modem) connected through fiber to whatever comes next, and assuming your whole house is on the same breaker panel which is properly grounded, the rest of the house should be safe. If you get hit close enough to the house, it will go through the power line and get everything, anyway. But yes, differential voltage between the power line and network cable can zip things. (I believe UTP ethernet is isolated up to 1000 volts.)

-- glen

Thanks Glen for the info. I agree about your electrical isolation idea, but what I was told is that I have possible different ground potentials when a severe thunderstorm goes over my residence and I have 75+ ft tall pine trees nearby (all around the house throughout the property). Any electrical charge goes to the ground and back into the house. So even though I have a whole house surge protector and additional protectors at each electrical outlet, the potential is there to continue having the charges running through any copper wiring (like phone, coax, data). I simply isolated my core computer- communication equipment with FDDI (the concentrator was $15 on eBay with cables at $10-20 each). Then I used secure wireless to connect to the laptops in the other rooms.

treet007 wrote in part:

Yup. Particularly if the phone and cable boxes (which usually have their own groundstakes and protectors) are not right next to the electrical entrance and groundstake.

The problem is that any nearby lightning strike does not immediately dissipate to zero potential. iThe Earth isn't solid copper. There is a serious gradient, sometimes kV/m. So one phone/cable groundstake can surge to a different potential than the main electrical. That potential then is imposed on all attached circuits and usually finds a weakpoint inside electronics.

The usual solution is to bond all of the groundstakes together, but this won't necessarily work if the groundstakes are far apart (opposite sides of building) and/or unbalanced.

Fiber is an excellent solution. The modems remain vulnerable. Their PSUs may give some isolation, particularly if the older (heavy) wound transformer. Ethernet will give 500V, but not more and is inevitably attached to computers with switched PSUs (poor ground surve isolation).

-- Robert

Yes, fiber is probably the best way. So how many hosts with fiber connections?

I had some machines where no 100baseT was available that I tried running on FDDI, but it didn't seem to be very fast.

I don't believe that FDDI/Fast ethernet bridges ever got very popular, so they might be hard to find on eBay.

Otherwise, there are 100baseTX/100baseFX media converters like

Probably that should be attached directly to, and directly grounded to, the appropriate device.

-- glen

Back in the 1990's when FDDI was still new and exciting there were "bridges" between Ethernet and FDDI. IIRC some required you "cripple" you FDDI network with the 1500 byte Ethernet MTU. Some claimed that even though they were _bridges_ they would IP fragment from FDDI to Ethernet.

I doubt such a thing has been made "new" in over a decade though so you will have to be scrounging with used equipment dealers, flea markets and recycling heaps. Or eBay :)

I'll second the suggestion of others that Fibre Ethernet may be a better way to go there.

rick jones

Probably a matter of horsepower and card design. EISA FDDI cards were probably never very fast. Others could be - PCI for example. Even the HP-PB (aka NIO) FDDI card could get to link-rate - if it was in the right sort of server where the HP-PB bus wasn't three hops away from memory.

FDDI cards were some of if not the first widely available NICs (well in the server space at least - eg HP, SGI, DEC :) to offer header-data split and checksum offload. Ah the grand days of the network MTU being >= the system page size :)

WRT PCI-X cards working in PCI slots, IIRC they only work in 64-bit

3.3v PCI slots, and that may also mean 66 MHz, not 33.

If google does have archives going back to the 1990's there should be posts there - including some from me and Vernon :) - talking about FDDI to Ethernet bridges. That at least should get some vendor and model names to help with the search.

rick jones

In my case it was MCA, and also for S-bus. Fast ethernet S-bus is probably affordable now. I knew about one 100baseTX MCA card, but they were rare, and I heard not very fast.

My understanding is that the speed of a PCI card is the maximum speed, so a faster card should work on a 33MHz bus at 33MHz.

A PCI-X card with the right notches should work in a dual voltage slot, but not in a 5V only slot.

I believe the one in the picture

There seem to be many PCI-X 1000baseSX cards on eBay, and it looks to me that they have both 3.3V and 5V notches. I don't know about the repeater/switch/hub, though.

-- glen

Robert Redelmeier wrote: (snip)

That should be fixable, though. Run the phone and cable right by the breaker panel, and ground them with a nice fat ground wire. (Cable shield, and phone surge arrester, hopefully one of the big ones like the phone company uses. I believe the traditional ones are gas discharge devices, which should be close to where the line comes into the house with a ground wire coming off of it.

The bonding should be fixed. I then wonder about the different length of wire (power vs. network) between two devices. If a pulse comes in the whole house (ground) will follow the pulse, but it will propagate at a finite velocity along the cable.

If the cables are the same length, any ground offset should arrive at the same time.

I thought it was to ground all the stakes to a metal cold water pipe. Though some newer houses use plastic water pipes.

-- glen

Hi Glen. I have searched for 100Base-FL a couple of years ago and they were about $100-$300 each. I checked for 10Base-FL, and they were hard to find. I will search again. Thanks for the idea. This would be useful at the demarc where the DSL comes in, and I can have the 10Base- FL between the DSL modem and the firewall-router.

BTW, sorry for the double-posting. I removed one when I noticed the formatting problem in my post, but apparently it did not remove it completely.

With more going to gigabit there might be used 100baseFX

It looks like either 100baseFX or 100baseSX would work. The wiki page says that 100baseSX should be cheaper, but that isn't always true on eBay. The supply of used FX might be higher (people switching to gigabit) and so might be cheaper.

For gigabit, 1000baseSX is the more obvious choice, but see

1000baseLX will work on multimode fiber (I presume that is what you have) up to 300m. The others will probably work through multimode for most sized houses.

-- glen

Glen, I just purchased two 10BaseT to 10BaseFL media converters for $15 each (+ shipping, of course) on eBay. I will just use this at the demarc between the DSL modem and the firewall/router.

I have 5 hosts (4 servers and a PC workstation) on the FDDI ring. One server acts as the FDDI-Ethernet router. I have not had any network contention at 100MBps (even compared to 100Mbps switch), and my next step is to setup 200Mbps using 2 FDDI rings. In my past life, I used to support a network with 2 FDDI rings supporting two buildings, so I guess you can say this is my "mid-life crisis" toy with the two Synoptics FDDI workgroup concentrators :-)

glen herrmannsfeldt wrote in part:

Basically more the NID boxes. Yes, that works.

Yes, probably around 2/3c . That's why it is important to have _one_ ground.

Check newer versions of the National Electrical Code. I think there have been some rust-type failures and cold water pipe grounding is no longer preferred. Deliberate ground-stake (or series of stakes in dry soil) is preferred.

-- Robert

(snip)

I should actually check, but I meant as a way to distribute the ground through the house. There are also stories of insulating water meters, and other ground discontinuities.

Last time I read it, one of the best was rebar in concrete.

-- glen

Glen and Robert, interesting discussions. FYI: I have one ground rod, which was installed with the new electrical panel when the house was renovated (around 2001). The installation and the inside wiring were checked by two electricians and the county inspector (part of the permit). Every copper line has proper grounding (Bellsouth Demarc, CATV grounding blocks) and they too have been checked. I have a main distribution frame (MDF) for the phone, data, and CATV using T586B specs for the CAT5e runs (phone and data). Now, the CAT5e runs behind the outer walls, in the crawlspace, and in the attic to their respective drops. Despite having my wiring checked by Bellsouth (twice) and others, it appears I have to accept the trees as the potential entry points for surges when a severe thunderstorm goes over my house. Note that the phone and power lines are buried from the telephone pole (at the street) to the house. Once I converted to fiber and isolated the phone lines, I no longer sufferred any computer equipment loss, except for a PC that has a Skype phone line gateway (for the rest of the land-line phones). In May, it suffered a partial damage where I now hear a lot of humming and static when using Skype, whereas my regular phone calls bypassing this PC do not have such background noise. Yes, I have replaced the Skype gateway unit, and the damage is in the PC.

First, I suggest creating a new discussion thread. Your question is not directly related the FDDI-to-Ethernet Bridge thread.

Try this to answer your question: