When preparing a crossover conversion on a patch cable, do I prepare both sides or just one?

Back story:

I decided to hook up my smart tv via cat5, instead of wireless. Buffering and signal problems just long overdue.

So in my arsenal I pulled out the longest cable I have. It's an old crossover cable I bought for my xbox.It's a 50 footer and wasn't long enough to reach my router... so I extended it with patch cable and fem/fem connector. Nope! I thought, Hmmm it's a crossover but extended with straight through, should be okay? I guess it didn't work, no connection. So I cut the end of the patch cable that was extending my crossover cable, and prepared a crossover, crimped a new fitting and I was in business. I had connection and smart tv worked (eg Netflix) with Wire Connection.

So a couple days later I'm having problems. Connectivity, no connectivity, on and off. So it begs the question. Why did it work, and why not now? The bigger question, should I have prepared both ends as a crossover? Yeah I'm a noob when it comes to hardware and networking. Thanks!



*where patch has one side converted to crossover.

  • Patch cables are straight cables. Making Ethernet Cables - Tricks of the Trade show how to make both straight and crossover cables. You should make a straight cable. That makes it straight end to end. – DavidPostill Dec 23 '15 at 10:45
  • Or buy an Ethernet cable of the correct length ... – DavidPostill Dec 23 '15 at 10:48
  • With modern network speed, it is very difficult to build your own cables which will pass the required tests unless you have a lot of experience. The tolerances are just too high, and errors are magnified with distance and speed. Back in the old days with 10Base-T, this wasn't much of a problem, but gigabit ethernet needs you to meet the high tolerances, and I doubt that you have a proper tester (several thousands of $). You are likely to continue to have problems until you buy a factory-built patch cable. – Ron Maupin Dec 23 '15 at 18:51
  • I think that was the problem. Intermittent connectivity. Thanks. – ejbytes Dec 23 '15 at 21:44
  • @RonMaupin It was probably the spec thing that made it intermittent. Thanks. – ejbytes Dec 23 '15 at 22:21

To directly answer the question asked, you only rewire one side to make a crossover cable. Making a crossover cable from a patch cable is simply the act of swapping the destination of two pairs of wires in the cable. Doing that to both ends will result in a (nearly) standard patch cable again (of course two of the wire colors would now be swapped but the functionality would be that of a patch cable).

In the early to mid 90s there was very little need for crossover cables. They were basically only used when creating peer-to-peer connections between just two devices or connecting anything to a router. For the last 10-15 years practically every router, switch, hub or nic you can buy has Auto_MDI-X which eliminates the need for crossover cables entirely. This feature is also only needed on one end of the connection so even devices which don't support this feature won't need a crossover cable if they are connecting to something that does have it.

Even if Auto MDI-X didn't exist, (almost) all home routers have builtin switches and that means you'd use a regular patch cable to connect to it. IMHO, you should probably just get rid of all of your crossover cables because it does exist and it is almost universal at this point. Even if you only have a single device on your network (which I strongly doubt is the case), it's still much better to have a switch on your network than to connect your one device directly to a single port router. With a switch you can easily add new devices as needed without unplugging the old ones.

  • I tend to hold onto all my junk lol. I bought that crossover I don't know when, over a decade ago I think. It was for my original xbox and the only way to play against a friend when he brought his xbox over. Ever since I had the 50' crossover sitting in a box. It was the only very long cable I had, with all the other 5-10 footers in the box. Your comment makes me think: I have several devices connected to my router, are you saying that I should use a switch instead? Single port? Sorry I'm lame with networking. It's one "in" (internet port) several "out" LAN1-LAN4. – ejbytes Dec 24 '15 at 2:55
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    Not exactly, I'm saying that you ALREADY have a switch. Your router is actually a combination router\switch. A pure router will only have a single LAN port and that port is meant to plug into either a switch or hub. Nearly all home routers are made with a switch built in. This means that even without Auto MDI-X you won't need a crossover cable for most home setups. SIDE NOTE: If you had a switch (as you do now) you could've used that to connect your XBOXes together without needing a crossover cable as well. You would've needed two patch cables and two free ports on the switch for them though. – krowe Dec 24 '15 at 6:52
  • Thanks! Good to know about routers. And I didn't know that about routers and that commercial "marketable routers" are actually a combo "router + switch" for home users like me. Good info. – ejbytes Dec 24 '15 at 7:14
  • I hope I've been helpful but you really should listen to the advice people are giving you. Your old Cat5 cable will work like this due to the magic of Auto MDI-X but it will work sub-optimally if it is attached to a gigabit network.If you're goal is to have a faster and more reliable connection then replace it with cat6. High def video WILL have trouble over a 100mb connection. This is not an upgrade you can make to an existing cat5 cable. Most cables will have either cat5, cat5e or cat6 printed on the side so that you can tell. Cat 5e will often be good enough but cat5 will not work right. – krowe Dec 24 '15 at 7:21
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    Also, I would personally never use one of those connectors. Throw that away too because it is just another failure point that you shouldn't need. It's not worth your time to fix those sort of problems. Get cables of the correct length for the location (or slightly longer) every time. Also, use cat5e ONLY if you've read the manuals for both the TV and the router\switch and BOTH say cat5e is best. – krowe Dec 24 '15 at 7:42

With modern network equipment a cross-over cable is not needed; the ports are auto-sensing and detect whether a cross-over is required and adjust for that automatically.

Also, it is not recommended (sometime not even possible) to use a cross cable with gigabit speeds.

Just use a single network cable of the correct length. It's very hard to correctly crimp an RJ45 connector on a cable if you're not used to doing it.

  • Auto-MDIX is part of the gigabit ethernet standard. Straight through or crossover cables work equally well. – Ron Maupin Dec 23 '15 at 18:44
  • @RonMaupin I figured as much. So I figured why not make use of this old orange 50' crossover I bought for my original xbox. At least I was able to reuse it. In my case it worked just fine when I plugged it into my smart tv (no extensions); but it was short by about 15 feet -- hence the extension question of what cable works when extending this crossover cable (which was problematic). – ejbytes Dec 23 '15 at 22:15
  • @wurtel I could simply buy another cable of course. But what fun is that? I am the type that likes to make due what what he has. I find it hard to buy new stuff if I already have stuff on-hand. In my case the crossover cable worked perfectly when I attached it for testing. It was when I decided to make it look pretty, wrapping around corners, under the carpet, around the wall, when i came up short. So I added the fem/fem connector and came up short. Then added a patch to make up the short... problems arose. – ejbytes Dec 23 '15 at 22:20

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