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Building a TCP/ IP Network Over Dark Fiber?
1101z asks: "Well I work for a public access station in a city where a second cable/phone/internet company has moved just started operating. Part of there deal with the city was to let us have (for free) dark fiber links between several location in the city and our studio, so that we would be able to cablecast live from those locations. As the computer guy I would like to be able to interconnect computer networks that already exist at several of those locations, when we are not using the fiber for cablecast. The question is what is the cheapest way to build a TCP/IP network over this dark fiber." I wonder if the fiber being used is related to this story, from a month ago?
Goal: TCP/IP over dark fiber.
So far as I can see, you can't do it.
As soon as you try, the fiber won't be dark anymore, invalidating one of the conditions. You can have dark fiber, or fiber with TCP/IP (or just pretty lights for that matter) but not both at the same time.
-- MarkusQ
"Dark fiber" is a nice buzzword, but has nothing to do with your question:
"I don't know how to design a network, can someone do it for me?"
Even if someone was willing to do this for you, the answer's no, since you've given absolutely no details about sites, number of users, applications.. really, anything useful to go on other than that you want to use TCP/IP.
There is no 'network in a box'; everyone's requirements are different. If you would post some of your requirements, we might be able to give you some ideas.
Are you trying to be funny, or are you just simple? Dark fiber is just what it sounds like: fiber-optic cable in the ground that doesn't have any light passing through it. It's not in use, in other words.
I write in my journal
I know it's a Friday night (in some places) but man, the responses on this Ask Slashdot really suck so far.
Short answer: you can set up a TCP/IP network over a dark fiber link for as little as a few hundred bucks, if you can find equipment for a good price. Here's how.
I'm going to make a couple of assumptions here; correct me if I'm wrong. I'm going to assume, first of all, that each link you've got access to is actually a pair of links; that's the way dark fiber is almost always sold. Second, I'm going to assume that you've actually got a dark fiber link, as opposed to buying a lambda. (Buying a lambda means that the telco is letting you use one frequency of a dense wave division multiplexed [DWDM] link. Not the same as dark fiber in the literal sense, but the same in most practical senses.) Finally, I'm going to assume that the telco has provided you with the necessary repeaters on the line so that you can actually push light from one end to the other without any additional hardware. If your telco has sold you (or given you, whatever) "dark fiber," chances are that all three of these assumptions are true.
If all of those things are true, then you're in a really good position. You can run anything across these fiber links that you could run across a shorter length of optical cable: FDDI, Ethernet (any speed), Fibre Channel, FireWire, HIPPI, whatever you want.
You said "cheapest," and what's cheap depends on what's available. If you can get your hands on a couple of old Ethernet switches with 10BASE-F or 100BASE-F (which are simply 10 Mbit and 100 Mbit Ethernet over fiber optic cable instead of copper cable) you're in business. Just plug the dark fiber into a switch at each location and poof! A single TCP/IP network running across the fiber to both sites, at 10 or 100 Mbps depending on what you can find.
My last company had, among other things, some Bay Networks (now Nortel, I think) stackable Ethernet switches with 24 100BASE-T ports and two 100BASE-F ports. I think they sold for about $2,500 when new (in 1998 or so), but should now be available for a lot less used. If you can find some of those used you'll be in good shape. Asante also makes switches like these; I've never used them, so I won't vouch for them, but you can buy them.
Another option would be to bridge Ethernet to FDDI; switches that do this should be available for really cheap, if you can find them, because FDDI fell completely out of favor in the mid-1990's. FDDI runs at 100 Mbps, just like 100BASE-F, but it has to be bridged, and sometimes this can cause problems with packet splitting and MTU sizes, especially on Cabletron switch gear. Unless you're looking at an absolutely killer deal, avoid the FDDI option.
If you want to go with something more up-to-date, you can run Gigabit Ethernet over the fiber links. It'll cost more, but you'll get better bandwidth. A good idea might be to buy a couple of cheap 100BASE-T switches with 1000BASE-T gigabit uplink ports (about $150 each), then equip each switch with a 1000BASE-T to 1000BASE-SX media converter (as little as $200 each).
Any of those solutions-- 10BASE-F, 100BASE-F, 1000BASE-SX, bridged FDDI-- would require nothing more than a switch with the right media type at each end; you wouldn't have to mess with routers or anything, and you wouldn't have to do anything fancy with your IP network. In fact, you wouldn't be limited to running just IP. You could run anything that can be carried over Ethernet: AppleTalk, NetBIOS, whatever.
If you get the gear for a reasonable price, you can run any of those networks for really, really cheap. When the links aren't being used for video, plug 'em in to the switches and go to town. When you're ready, just unplug 'em and go back to video. The link will be down, but neither the switches nor the computers will care.
I write in my journal
http://www.cisco.com/en/US/products/hw/modules/ps8 72/ps4025/index.html
plus a Catalyst switch at each end:
* Cisco Catalyst 2948G
* Cisco Catalyst 2980G-A
* Cisco Catalyst 2950 Series
* Cisco Catalyst 3550 Series
* Cisco Catalyst 4000/4500 Series
* Cisco Catalyst 6500 Series
Welcome to my friends list my drunk european friend!
Your sincere dedication to giving this guy such a completely incorrect answer is very admirable. It fills my heart with joy to know that there are still people out there who want to care.
~GoRK
Everyone seems to be focusing on puting fibre switches at each location, which I think is an unnecessary expense. The way I read the question you already have existing network at each location, and you just want to hook them together.
It seems to me that you could just get a few PCI fibre NICs and use them to set up existing machines at each location as bridges. I don't remember how much they cost, but it would definately be cheaper than switches. You'd have to make sure you had the right plugs/jacks, obviously.
It seems to me that it would be a pretty simple thing to do.
Under capitalism man exploits man. Under communism it's the other way around.
Ahh, the dark fiber is strong in this one..... he will be a good network warrior.
As part of a deal with a new pet store, the city has been provided several free "dark" carrier pigeons.
Can someone please help me discover what additional hardware I need to do RFC 1149/CPIP?
I would also try "goo-gling" but I'm a grown man and it sounds like something more approbate for a baby to do.
Without knowing the fiber type and the length of the runs it is not possible to answer the question
You're new to this whole "dark fiber" thing, aren't you? When a telco sells you "dark fiber" they're either literally selling you unused MMF, with repeaters in place, or they're selling you an unused lambda. In either case, the interface to customer equipment is multi-mode fiber, and you can run anything over it that you would run over a shorter piece of fiber.
But, what are the distances? Are the runs one kilometer or are they 30 kilometers? What type of fibre is it? How may connections are there in the fibre? Has the fibre been tested(characterization) to determine dispertion levels due to fibre quality, distance and connections.
If you were pulling your own glass, those would all be relevant questions. Since these connections come from a telco, the telco takes care of all of those things for you.
Look, buying dark fiber is like buying a dry pair from the telephone company. You have a pair of wires on one and and a pair of wires on the other, and you can use them as if they were opposite ends of the same piece of continuous copper. Are they really? No. The signals on your dry pair pass through switches and muxes from here to there. But the telco guarantees that the dry pair will act like a single piece of wire.
Dark fiber is the same way. No matter what is actually between you-- DWDM mux and demux, repeaters, microwave links, whatever-- the telco guarantees that the dark fiber link will act like one long piece of MMF.
Going further, what is cheap? It's rather subjective, don't you think?
Sure, it would be subjective if he'd said "cheap." If he'd said, "What's a cheap way to built a TCP/IP network over dark fiber?" there would have been hundreds of good answers. But he didn't say "cheap." He said "cheapest." And my answer, to my knowledge, comes down as the cheapest possible way to run TCP/IP over dark fiber.
Cheap to some people means a couple hundred dollars. It's highly unlikely that he could build the network for that.
It's highly likely that he could build the network for that, if he could get ahold of cheap used 10BASE-F or 100BASE-F gear. With the current business environment, the market is positively saturated with this kind of gear for pennies on the dollar.
The poster didn't come close to providing the required information with the question and got what he deserved.
Yup. As of the time that I wrote my post, the submitter had received about a dozen smart-assed, sarcastic responses and two helpful ones. Par for the course for an Ask Slashdot.
I write in my journal
You're new to this whole "dark fiber" thing, aren't you? When a telco sells you "dark fiber" they're either literally selling you unused MMF, with repeaters in place, or they're selling you an unused lambda. In either case, the interface to customer equipment is multi-mode fiber, and you can run anything over it that you would run over a shorter piece of fiber.
Again, you assume way too much. First of all, the poster says that the city was to let us have (for free) dark fiber links between several location in the city and our studio. He did not say a telco was providing him with anything. Further he says dark fibre links. He does not say that they are providing bandwidth or lamdas, meaning that it cannot be assumed that they have repeaters or muxes or DWDM equipment on these links. It is entirely possible, if not likely that they are getting strands of glass and nothing more.
You also talk about multi-mode fibre. While it is true that telcos often provide a multimode fibre connection to their customers, this is just a short link back to the telco's multiplexer on a single mode sonet ring. This case could easily be just glass strands, like I said before. If that is the case then they are much more likely to be single mode because multi mode cannot run the same distances that single mode can. If the run is longer than a kilometer it will almost certainly be single mode and require totally different equipment than the multimode scenario you propose. Again we don't know that from the post, as I stated earlier the poster did not provide nearly enough information to answer the question. But, maybe you are correct, provided that your other assumtion was correct when you said You're new to this whole "dark fiber" thing, aren't you?
The long answer is that if you haven't done this before you better get some consulting help. Chances are you are talking about a ring topology and are going to be linking sites with different networks.
Perhaps you have telco supplied networks for each office hooked up over DSL or T1. If that's the case, have fun getting routing working without having the telco people disconnect you. Good luck reconfiguring the telco routers for that matter.
Routing complex networks is tough. Do you already have VPN's interconnecting these sites? Are you going to be introducing redundant routes? How are you going to manage these routes? IOS can suck if you've never seen how to configure routing processes. Routing software is also complex. Ripv2 is about as simple as it gets and it doesn't offer much control over which route you take -- the only metric is hop count. OSPF has design guides as big as phone books.
If you have a bunch of nats at your different locations, do the networks overlap? Are you going to have to renumber your networks?
If you are just playing in your spare time, you won't be able to do this for under a few grand. Fibre connections are generally not cheap. If you're lucky you could put a few fibre nics into a couple of linux boxes, but I don't foresee those nics being under $400 each.
If this is to be a business network, do it right from the start or you'll make yourself look stupid. People expect the stuff they don't understand to just work. There will be very little tolerance if services are going up and down and your fibre links are to blame.
-- DrZaius - Minister of Sciences and Protector of the Faith
Hmmm...seems everyone wants to either be a smart*** or overanalyze this. First off: It appears that he is working with the local cable company, so, actually, he has already defined what sort of issues and designs he will have with this. Dark fiber from a cable company means a point to point link. If he has multiple offices, this will generally mean that there will be a hub and spoke design on the fiber from a central location to the edge sites. In addition, the local cable co will most certainly provide the distances and loss budget for the fiber, making selection of equipment an act of trivia. The only thing not defined was the type of network he really wants, but in this case, it is also probably completely irrelevant. If you can't put all your services over TCP/IP, then you shouldn't be maintaining a network. First off, gear selection. I work for a Cisco-centric company, so most of my experience is with Cisco, but I have worked with Foundry and Nortel and a few others. If you want reliable, Cisco is certainly acceptable, and you can always put a contract on it to meet your needs. Second, protocol selection. Well, he wants TCP/IP. This will certainly be easy enough. Engineer the backend properly (IP addressing 101, and get a router for the links, your done. If you need to convert Analog Video to H.323, there are plenty of vendors who can do this. If you need COS, again, there are plenty of solutions. Layer 2 Selection. My recommendation would be to go with GigE. This is certainly cheaper than going with outdated FX technology if you buy new, and more reliable. When you have the distances and loss budget of the fiber links, you can select the appropriate GBIC's for the link, and if you get light at both ends, you have a network. In Cisco terms, I'd go with a 3550-12G at the core if you have more than 2 locations. This will be a reasonable fiber concentrator ($9,999 list) and also does QOS, policing, and routing (both packet and protocols, such as EIGRP). At the edge, depending on how much intelligence you need, you can put in Cisco 3550-24's, either EMI or SMI flavor. The EMI boxes are routers (same code as the 3550-12G. The SMI boxes have port routing in the newest code, but won't run routing protocols. These boxes will allow you to converge your network (data, VOIP, and video) and really don't have a horrible price tag. The SMI lists at $2,999 and the EMI at $4,999. This doesn't include GBIC's but the max cost on those is long-haul (Cisco ZX) which lists at $5,995. The intermediate reach LX is only $995. Don't mess around with MMF (SX GBIC's) if you don't have to. Even if you do short haul, this will be a more stable solution and will allow you to repurpose gear in the future. The big gotcha with this is support of the fiber. Most of the time Cable dark fiber contracts mean that the customer is responsible for paying for repair of the fiber. Find out who is responsible for the fiber, and make sure you budget appropriately if the cable company is going to charge you for repairs on the lines. If they won't do it, find someone who can (check the contractors who already work with the cable company, they already know the systems and people) and get them on retainer or whatever. Many schools and governments have ended up shocked because they had to find someone in the middle of the night with a fusion splicer to fix a damaged link. Or the cable company sent them an outrageous bill for repair after the fact. This sucks, because it is hard to budget for an 18-wheeler gone awry in an ice storm. If you do it this way, you can treat the fiber just like Ethernet, and be done with it. You don't have to relearn protocols, and you will have a decent growth path for the future. My networks (that look just like this!) are WAN's that I treat like LAN's, and they are easy to support. Gybrwe
Look,
Without the additional details that are "required" by some of the posters, you can only speculate at an answer. Twirlip Of The Mists has done that, and had some very reasonable suggestions.
However, for a complete and assuredly valid answer, we simple need for information. As he said "let us have (for free) dark fiber links" that may mean that he really has nothing but fiber between buildings. Telcos aren't known for their sweeping generosity. He may have a lambda, which is absolutely reasonable in a metro area, which would give him something to work with.
If the fiber has sufficient bandwidth, he could split the fiber into data and video traffic (my high school used an OC3 in this manner for ITV classes and Internet access), but this would likely cost a good deal more.
The issue I have with the whole thing is "...when we are not using the fiber for cablecast." If you want cheap, as Twirlip Of The Mists suggests, that will mean (I could be wrong) physical disconnection of network cabling at both ends each time you broadcast, and then re-connection after broadcast. Would you have trained network people at each "public access" location, or would you end up driving around town before shows? Is it worth it to you?
Granted public access television isn't rolling in money, but to make your life easier, you probably want something you don't have to physically connect each time. Of course, you could get a fiber switch, and some X10 appliance switches and the Home Connect kit. Then you could just call up and switch off the data and switch on the feed.
I want it to be clear that I am not saying that would work.
That what was all this school was for... to teach us how to solve our own problems. -- janeowit