Linux Token Ring Support Bringing Down Corporate Nets?

mjh asks: "I've been running Debian GNU/Linux on my company supplied laptop for 3 months now. I got permission from my manager to run it on the network, but I did not go through the somewhat rigorous process of getting the software certified. I have legitimate business reasons for using it on the corporate network (which is why my manager approved it). I even managed to get Lotus Notes to run under wine so I never had to boot into Winders at all (unless someone sent me a PPT doc). I was pretty happy...until I brought the entire network down." Anyone else running Linux on a Token Ring network who would care to talk about their own experiences?

"My company runs Token Ring at the office (puke!) I got drivers from the card manufacturer (Madge), and I'd been happily churning along. Then last week, we started seeing a bunch of errors on the network. These errors would bring everyone on the ring down. After a week of this kinda stuff, they eventually isolated it to me.

Reboot the laptop into Windows and the network card works just fine and they don't see any ring errors. Reboot into linux, and suddenly they start seeing ring errors. I don't really grok token ring, so I'm not entirely certain that I know exactly what the problem is. But, whenever I brought the token ring on line under linux, they saw ring errors, which eventually (as I understand it) would bring down the entire ring. Switch cards (same model) and it continues to happen. It looked to me (and the network analysts) that the Linux driver was causing the problem.

I tried switching to an IBM token ring card, but there's a bug and I hadn't patched for this. The people with the fluke would not wait around while I tried to figure this out. I didn't have any other token ring cards that I could try.

In the end, I agreed not to boot into Linux unless I went into the conference room (which is one of the only rooms in the building with ethernet ports). How should I have done this differently so that using Linux would have been a more positive experience for my company?"

Comments

Re:Tolken Ring Networks.... (SOUR GRAPES)

[Leimy]

No excuse. If you say you support something and that support is stable... it should be so.

Fix it... don't say its not worth having anyway. Or if its not worth having strip token ring support out and save a few kB.

Re:actually

[RogrWilco]

I had the same thing with a Microsot implementation of DHCP taking down My SCO server. I found a patch on SCO's website, which completely resolved this issue.
Perhaps the biggest problem in the computing industry in general, and in mixed os environments in general, is the fact that standards are often never actually standards. Even without casting blame on any of the products in question, standards are often not as defined as they should be, and any liberties or assumptions made by programmers, usually ends up in catastrophic incompatibilities. Regardless of where the blame lies (MS, BSD or Linux not following standards), the solution is to viehemently define standards so that there is no question about their implementation.

Have them wire your desk for ethernet.

[John Harrison]

My office is mostly token ring, but we have some people who have asked for ethernet and the networking guys have been very willing to switch a port over to ethernet. They just need to move some cables on the patch panel.

If you already have ethernet in a conference room it might not be too hard to just have the port you use added to whatever hub they use for the conference room.

It seems that you are running on a laptop since you can move you computer to the conference room. Another option is to insist that they put up an 802.11b network. You could then wander freely and have wireless ethernet. Even better!

Re:Tolken Ring Networks....

[rdean400]

Not true. There's gigabit TokenRing just like there's gigabit Ethernet. What's more, TR has collision avoidance built into the protocol, where Ethernet networks have to be architected in star topologies to avoid collision, because Ethernet responds horribly.

Of course, Ethernet costs so little that you can build an Ethernet in a star topology for less than a TokenRing in a ring topology. "Good enough" wins again.

it's your vendor's problem

[mj6798]

Why isn't the Madge driver in the Linux distribution? Did it come in source form or in binary form? In any case, if the driver doesn't work, it's Madge's fault, doubly so if it is binary only or proprietary. The fact that a malfunctioning driver easily brings down a ring is an inherent problem with TokenRing.

You do have a way out: use the IBM card. It was working a few years ago, and I imagine it's still working today. Yes, you do have to patch the kernel--what's the problem with that?

If that's not to your liking, you can throw money at the problem and buy a TokenRing/Ethernet bridge and use an Ethernet card on the Linux machine. Maybe your managers will see the light and convert more of your network to Ethernet.

In general, TokenRing is dead technology. Many operating systems just don't support it at all anymore. How long should Linux carry the burden of supporting outdated and flaky technologies?

Re:Voodoo debugging in the Good Old Days

[billstewart]

Token ring was often more reliable than Real Ethernet Thick-wire with Vampire Taps - the mechanical connectors were better than just chomping your way into a coax cable with the possible risk of trashing the code enough to get reflections. I'm not sure if it was better than connectorized thinwire or not, and it certainly wasn't better than Cat5 10baseT, at least if you used genuine Cat5 and didn't cheat with Cat3 (or didn't use cable-TV coax instead of proper thinwire :-) Back when I used to deal with this awful stuff, I had one customer for whom the original Ugly Shielded Twisted Pair token-ring really did make sense - they were a city's Department of Water and Power, and they had lots of Really Big Electric Motors which were a really bad electrically noisy environment, and their network needed all the help if could get. These days I hope they're using fiber.

Re:Voodoo debugging

[mjh]

A "receiver congestion" error is caused when the Linux driver doesn't remove packets from the card's buffers fast enough. In theory, they are suppose to indicate that packets are coming in too fast for the machine to handle. In practice, you see this happen when machines "hang" and fail to empty their queues. You might be running some sort of libpcap packet-sniffer on the system or have the adapter running in promiscuous mode (do an ifconfig to check) that is having some sort of pathelogical condition.

Wow! This has *got* to be what the problem was. This problem started showing up right around the time of the big Code Red hubub. So I installed snort just to watch and see what was going on. Snort, of course, uses libpcap and puts the card into promiscuous mode. Right afterwards, is when we started seeing problems on the network.

My guess is that your admins are just getting testy over the fact that your Linux box re-inserts itself more often than Windows boxen, causing a higher number of relatively harmless burst-errors. When they diagnose problems with the ring, they notice that your machine causes the highest number of errors, and therefore blamr any ring failure on you.

Holy schnikies! You must have been in the room! That is *exactly* what happened. They discovered these errors and basically said that the errors were the *only* thing that they could see that was wrong with the network. From this they concluded that the problem must have been caused by my running Linux.

About the only thing that does not fit, is that since I've stopped running Linux on the network at work, the problem has completely gone away. Not a single recurrance in several weeks time (I actually submitted this article to /. many weeks ago. Why it took so long to get accepted, I dunno.) They did, as part of their process of troubleshooting replace all of the TR equipment in the closet. But even after they did that, we were still having problems. So far the only thing that seems to have fixed this problem was me staying out of Linux.

Thanks for you're very informative post!

Re:No problems with my Olicom card

[Anonymous Coward]

Where I work we installed ibm cards and used the driver that came with our redhat 5.1 distribution. The only problem we encountered was getting messages about network problem resets. It was reporting problems being corrected that a bridge was having in another building - a problem our IT people knew nothing of. After informing our IT department, we commented out the message in the driver. The sytem has been running for around three years now and has not been the cause of a single problem on the Token Ring network. We also installed two ethernet cards in each machine along with the TR card and they all get along without any problems.