Token Ring/Ethernet Hybrid Network?

Matthew Branton writes "I am currently a student and for the past year have been forced to use my school's antiquated token ring network. No More I say! I am interested in setting up an internal (to my room) ethernet network, which integrates with the school's token ring one. This desire stems primarily from the poor token ring support in Linux, and the lack thereof in Beos. Finally, I am looking to do so in the most cost effective manner possible (this is where Linux fits in), can anyone share their solutions? " I'm not very well versed in Token Ring networks, so I don't know right off how feasible something like this is. Can anyone shed some light on this subject?

Re:From a long time Token Ring user

[Dumas]

Bridging between ethernet and Token-Ring is really not a good option. It's basically a kludge. IBM sells (sold?) a box that claimed to do it, but even IBM, who invented Token-Ring, couldn't get the thing to work all that well. We tried using one once, but gave up on it.

So, as others have said, stick to routing, TCP/IP, and proxy ARP if at all possible.

You are going to have to bridge

[DrZaius]

You are going to have to get a device to act as a bridge between the two networks. There are commerical products, but you should be able to find a token ring card and just set up a NAT or masq between the two networks.

I have not had much experience with token ring under linux, but as far as I know, it should be supported on a card by card basis (there is token stuff in the kernel). You'll just have to find some of those cards.

From a long time Token Ring user

[RobertGraham]

Easy answer: drop a Token Ring and Ethernet card in your Linux box and route between them. If routing gets ornery, then use proxy ARPs.

Problem: This is easy if you are using TCP/IP, but if you want access to other things, like NetBEUI, AppleTalk, SNA, etc., then you are screwed.

Problem: If you are using TCP/IP and you only get one IP address, then assign completely unrelated IP addresses to the Linux box (like 192.0.2.5 and 192.0.2.6). Then turn on "Proxy ARPs", which tells your box to respond to ARPs for the machine(s) behind it. Then use the "route" command to hard-code routes back-and-forth through the box.

You can "bridge" instead of "route". Routing, as described above, analyzes the IP packet, and strips off the Ethernet/TokenRing headers. Conversely, briding ignores the IP contents and does some translation magic to convert between Ethernet and Token Ring. The conversion algorithm is straight forward. There have been briding programs for DOS for ages, and there might be ones for Linux. Writing one on libpcap wouldn't be too hard -- if you knew what you were doing and were intimately conversent with the protocols.

Even a Win95/Win98/WinNT box would be pretty easy to set up for routing in much the same way. It supports proxy ARPs, hard-wired routing, and the like. It probably has better support for Token Ring.

Do you need any protocol but TCP/IP?

TR / Ethernet

[JesseD]

The last shop i worked in did this exact thing, one TR network for user desktops, and ethernet for the server/router/firewall environment... and the options posted above are exactly right... although the most effective is the bridge solution since it will translate and forward the whole frame, regardless of protocol. And yes, linux has bridging support (i believe the 2.2+ kernels have experimental bridging modules?),
good luck.

IT could get ugly

[Barn_Owl]

Token ring and ethernet are not compatible median in my experince. You would need a box to act as bridge. If there was enough interested ppl at teh college, You amy be able to convince the Admin(maybe) to set up a box for this or let you.

Been there...

[PhysBrain]

I was in almost exactly the same situation about two or three years ago. The university had gotten duped into installing token ring all over campus at some point in the past, but the CS department had recently aquired a couple unix boxes which were not Token Ring friendly. A friend and I were put in charge of these boxes and one of our most daunting challenges was to get them to talk to the campus network.
Our eventual solution was to set up a i486 box with a Token Ring and ethernet cards. We set the box up as a firewall with IP masquerading. The unix boxes were on the own internal tcp/ip network (192.168.?.?) so the rest of the world could not see them. We could still get to them remotely by telneting to the linux box first, but I imagine there are more sophisticated ways of accomplishing this.
Since it's not likely that your university is going to give you more than one IP address for your room/port(s) this may be what you need to do. Everything you need to know should be in the NET-3, Firewall, IP-Masquerade, and other related HOWTO's.
Good Luck.