• GM (unregistered)

    Someone did this at a company I worked at years ago. She was juggling multiple boxes and network cables, got it wrong and plugged one socket into another in the confusion. Brought the entire corporate network down. Tragically, this became a disciplinary matter, and she was given a final written warning for her troubles, which I think is grossly unfair, as it's not her fault they skimped on decent switches.

  • (cs)

    shouldn't a (decent) switch get it when two ports are linked together and just disable them both?

  • (cs) in reply to FrankyBoy
    FrankyBoy:
    shouldn't a (decent) switch get it when two ports are linked together and just disable them both?
    I guess the key word here is "decent".

    And, to answer your question: Yes.

  • Moo Cow (unregistered)

    It's always nice when problems that are at least 30 years old still aren't solved by standard equipment.

  • Jim the Tool (unregistered)

    So what's the WTF? It can't be the teacher (I've studied networking (admittedly I didn't do very well; I didn't pass), but I didn't know that plugging one port into another would bring down a network (and/or switch). So is the WTF the switch?

    captcha jugis. Did the teacher have big jug's?

  • Cheong (unregistered)

    Perheps it's not so common for plugging both side of cable in the same switch, but when working with multiple switches on the rack, "accidentially plugging cables from different switch to from circular pathway" happens a lot, especially when they don't buy cable with different color for uplinks plus the cables are not labeled.

    There is some reason they insist we do our work only at Saturday afternoons.

    Two cents from my experience working as techincan of vendor.

  • Craig (unregistered)

    I used to work in a school about ten years ago and this happened all of the time there. Staff and pupils (more often staff) quite frequently would create network loops/broadcast storms by plugging the network back into itself - more often than not they thought they were being helpful plugging the cable into a socket that it had come out of. I got very good at quickly walking the hierarchy of switches to track down the source of these. When I pulled a desktop out of place for maintenance I tried to remember to take the network patch lead with me so it couldn't happen, but that wasn't always the way.

    Sadly it was just as I left that job and moved on that we were starting to migrate to managed switches which could detect and shut down the source of broadcast storms on their own.

  • RFox (unregistered)

    Before switches became decent we used to have this problem all the time because we'd have a set of ports in conference rooms, and a pile of cables so people could plug in their laptops...every now and then someone would get to playing with the cables and...well you can guess the rest.

  • Kristof Provost (unregistered) in reply to flop

    I think that I shall never see A graph more lovely than a tree. A tree whose crucial property Is loop-free connectivity. A tree that must be sure to span So packets can reach every LAN. First, the root must be selected. By ID, it is elected. Least-cost paths from root are traced. In the tree, these paths are placed. A mesh is made by folks like me, Then bridges find a spanning tree. -- Radia Perlman

  • QJo (unregistered)

    I would expect this is not a rare occurrence. Someone did it in one of our spare offices once. Since it was the first time anybody in our IT team had experienced this happening, it took most of the day to fix it, during which time the developers were being blamed (I think we had implemented jgroups in our flagship product, and had been having trouble with it hanging the app regularly).

    Once the problem had been found, a company-wide email went out and as far as I know it never happened again.

  • QJo (unregistered) in reply to Jim the Tool
    Jim the Tool:
    So what's the WTF? It can't be the teacher (I've studied networking (admittedly I didn't do very well; I didn't pass), but I didn't know that plugging one port into another would bring down a network (and/or switch). So is the WTF the switch?

    captcha jugis. Did the teacher have big jug's?

    TRWTF is computer equipment that behaves like this.

    Oh, and you have perpetrated a greengrocers' apostrophe. Intentionally for humorous effect?

  • (cs)

    When he said both ends were "plugged into the socket", I immediately thought an electrical socket for some reason.
    Well, there's yer problem.

  • (cs)

    As I read the thread, it occurs to me that the real WTF is the connector design on network cables. The plug is shaped the same way on both ends, reinforcing this kind of behavior among users.

    We don't have problems with users of electricity running an extension cord between two outlets, do we? Because they can't

  • ¯\(°_o)/¯ I DUNNO LOL (unregistered)

    I guess that explains why Slashdot is down this morning. Someone plugged a wire into two Ethernet ports!

  • RandomDude (unregistered)

    The first thing any experienced admin does when bringing up a switch is enabling STP (http://en.wikipedia.org/wiki/Spanning_Tree_Protocol) if it's not enabled by default already.

    So, in a institution/company with a decent admin, decent rules and decent budget, you would buy switches that support STP and have it enabled. That's standard stuff today and things like this are either stories from the past or a combination of inexperienced/incompetent admin, stupid rules when buying equipment or small/zero budget so that you go with the cheapest low-end switches you find.

    That being said, I saw this happen like 5 years ago when in a different office / different company STP was not enabled though it was supported (nice HP ProCurve Layer 3 switches).

  • Neil (unregistered)

    Engineer: "Why do you have STP enabled on this bridge?"

    Engineer disables STP.

    Broadcast storm ensues.

  • faoileag (unregistered)

    If that was / is a common problem with switches, why don't the admins get a handfull of old cables, cut off the plugs with, say, 2" of cable remaining, and fill all empty sockets with those dead plugs? Perhaps with some gaffer tape around the stumps of network cable for easier recognition in the forest of cables that usually can be found behind a switch?

  • Neil (unregistered)

    On the other hand, STP isn't a panacea:

    Accidentally create loop between two Gigabit switches and a megabit switch.

    Gigabit switches shut down their direct link to break loop.

  • faoileag (unregistered) in reply to vt_mruhlin
    vt_mruhlin:
    As I read the thread, it occurs to me that the real WTF is the connector design on network cables. The plug is shaped the same way on both ends, reinforcing this kind of behavior among users.

    We don't have problems with users of electricity running an extension cord between two outlets, do we? Because they can't

    Perhaps because then you would also need two kinds of sockets on the switches?

  • Andrew Luecke (unregistered) in reply to RandomDude

    Exactly what I was going to say. In fact, we even install Smart switches into homes these days due to Sonos (which causes network loops sometimes, because there is no way to disable the ethernet<->mesh network bridge on them).

    Sorry, this isn't really much of a WTF I feel. We see network loops quite a bit actually (its very easy to do accidentally).

    And, anyone administrating the network should know how to troubleshoot networks to locate them (its a lot more painful without STP though obviously).

  • Chris Gonnerman (unregistered) in reply to QJo
    QJo:
    Since it was the first time anybody in our IT team had experienced this happening, it took most of the day to fix it, during which time the developers were being blamed (I think we had implemented jgroups in our flagship product, and had been having trouble with it hanging the app regularly).
    I see this with my school customers all the time. If you are using unmanaged switches without Spanning Tree support, it's almost guaranteed that making a loop will kill the network.

    Here's what happens: A broadcast packet comes into the switch, and is forwarded out all the ports. That means it goes out both looped ports... and arrives at both of them. Since it's a broadcast, it goes out again from all ports, including the looped ones. Voila... infinite loop in hardware.

    Meanwhile, more broadcast packets appear all the time...

  • Greg Hirsch (unregistered) in reply to QJo
    QJo:
    I would expect this is not a rare occurrence.
    Agreed; who hasn't accidentally done this?

    Exchanging the IP of one's own machine with that of the default gateway is another easy way to bring down everything...

  • anon (unregistered) in reply to faoileag
    faoileag:
    vt_mruhlin:
    As I read the thread, it occurs to me that the real WTF is the connector design on network cables. The plug is shaped the same way on both ends, reinforcing this kind of behavior among users.

    We don't have problems with users of electricity running an extension cord between two outlets, do we? Because they can't

    Perhaps because then you would also need two kinds of sockets on the switches?

    Just design a cord with a different plug in each end and a socket that can accomodate both. Problem solved.

  • faoileag (unregistered) in reply to anon
    anon:
    faoileag:
    vt_mruhlin:
    As I read the thread, it occurs to me that the real WTF is the connector design on network cables. The plug is shaped the same way on both ends, reinforcing this kind of behavior among users.

    We don't have problems with users of electricity running an extension cord between two outlets, do we? Because they can't

    Perhaps because then you would also need two kinds of sockets on the switches?

    Just design a cord with a different plug in each end and a socket that can accomodate both. Problem solved.

    You don't think that a socket that accomodates both ends of a network cable would somehow work against the original purpose of having a different plug on each end?

  • anon (unregistered) in reply to faoileag
    faoileag:
    anon:
    Just design a cord with a different plug in each end and a socket that can accomodate both. Problem solved.
    You don't think that a socket that accomodates both ends of a network cable would somehow work against the original purpose of having a different plug on each end?

    Probably, yes. But when have that ever stopped anyone in this line of work?

  • Jim the Tool (unregistered) in reply to QJo
    QJo:
    Jim the Tool:
    So what's the WTF? It can't be the teacher (I've studied networking (admittedly I didn't do very well; I didn't pass), but I didn't know that plugging one port into another would bring down a network (and/or switch). So is the WTF the switch?

    captcha jugis. Did the teacher have big jug's?

    TRWTF is computer equipment that behaves like this.

    Oh, and you have perpetrated a greengrocers' apostrophe. Intentionally for humorous effect?

    Actually, it's an apostrophe to indicate a missing letter or letters. Such as in the common words: don't and wouldn't (where the missing letter is 'o').

    captcha: jumentum. Jump + momentum. Using jumping to get some momentum. Like: "While most of the runners were still at the starting blocks, Jim was jumentuming." cough

  • Herr Otto Flick (unregistered) in reply to FrankyBoy
    FrankyBoy:
    shouldn't a (decent) switch get it when two ports are linked together and just disable them both?

    We managed to bring down our DC host with some bad STP on our switches that their switches then confounded by listening and responding to - one big loop, no data in or out of DC for 1 hour before they worked out what was wrong.

    These weren't unmanaged switches, ours were managed Dell switches (ok, so still cheap and nasty), theirs were Cisco (I think).

  • lolwtfbbq (unregistered) in reply to Jim the Tool
    Jim the Tool:
    QJo:
    Jim the Tool:
    Did the teacher have big jug's?

    Oh, and you have perpetrated a greengrocers' apostrophe. Intentionally for humorous effect?

    Actually, it's an apostrophe to indicate a missing letter or letters.

    And which letter did you omit in the word "jug's"?

  • wandering GM (unregistered) in reply to Greg Hirsch

    Been there done that, the network stayed up though that machine needed rather allot of work to get it to reconnect. I've never seen a loop done though, mostly because the people I worked with(around) couldn't find either cables nor open ports. Setting a whole schools computer lab to switch between all of the IP adresses the network could handle in synch was fun, but I did need the network down flat, fast. All of the other computers in the district were running LOIC aimed at the lab computers as well, because the thing needed to fall flat and crash before it would close the hole that had been patched(don't ask me why they couldn't cycle it when they patched, it just asked when I tried to access the gateway. Blackhat tools and grayhat exploits to do a whitehat job without leaving evidence(the file servers were open the the greater net without password).

  • faoileag (unregistered) in reply to lolwtfbbq
    lolwtfbbq:
    Jim the Tool:
    QJo:
    Jim the Tool:
    Did the teacher have big jug's?

    Oh, and you have perpetrated a greengrocers' apostrophe. Intentionally for humorous effect?

    Actually, it's an apostrophe to indicate a missing letter or letters.

    And which letter did you omit in the word "jug's"?

    Well, since Jim the Tool's original post ended as "captcha jugis. Did the teacher have big jug's?"... I buy an "i"! And I want to solve!

    captcha facilisis. facilisis is jugis' her sister ;-)

  • anonymous (unregistered) in reply to faoileag
    faoileag:
    vt_mruhlin:
    As I read the thread, it occurs to me that the real WTF is the connector design on network cables. The plug is shaped the same way on both ends, reinforcing this kind of behavior among users.

    We don't have problems with users of electricity running an extension cord between two outlets, do we? Because they can't

    Perhaps because then you would also need two kinds of sockets on the switches?

    There are already two kinds of sockets on the switches. There are two functionally different types of port with the exact same physical size and shape.
  • Hovercross (unregistered) in reply to Neil
    Neil:
    On the other hand, STP isn't a panacea:

    Accidentally create loop between two Gigabit switches and a megabit switch.

    Gigabit switches shut down their direct link to break loop.

    Not if STP is set up right on all three switches - in modern spanning tree, the path cost between each of the gigabit switches and the fast ethernet switch will be 200,000 and between the two gigabit switches will be 20,000 - this should lead to one of the switches breaking a connection between the FE switch and the gigabit switch, with there "where" depending on a whole host of factors, but primarily the switch that has been elected as the root bridge.

  • (cs)

    One morning in the early 1990s, our little 15-employee company was humming along, when all at once, every PC (80286, DOS 3.3, WordPerfect 5.1) froze hard. I headed for the file room to check the AS/400. It was still up, but the system operator message queue was filled with "Token-ring is beaconing" messages. While I was puzzling over what "beaconing" meant, the messages suddenly stopped, and another employee stuck her head in the file room. "[Claims Rep] moved a computer from one cubicle to another. Could that have caused a problem?"

    Off I went to the cubicle, which contained an IBM XT. I checked its cabling, and discovered that the only two connections that could have been mixed up, were. It hadn't occurred to the claims rep that the cable with the green 16/4 label, should attach to the port on the computer with the green 16/4 label. She'd plugged that cable into the Hercules graphics card instead, and the monitor cable into the token-ring card (both 9-pin mini D-shell), and powered up the PC.

    From then on, the claims rep called me when her department needed a PC moved.

  • Raptor (unregistered)
    While it was rebooting, he heard the volume of the students in the computer room explode

    Not the best phrasing to use when describing something occurring in a war zone.

  • PC Amok (unregistered) in reply to FrankyBoy
    FrankyBoy:
    shouldn't a (decent) switch get it when two ports are linked together and just disable them both?
    Why would you expect anything solid left in the bathroom to not be sh*t?
  • NoJoy (unregistered)

    Or when a D9 token ring connector is plugged into a D9 CGA adapter output - that also was bad. Catpcha: Bene - only half a benefit.

  • (cs)

    Reminds me of my last company where our server room was protected under lock and key. So when this happened, as it inevitably would, it was easier to track down who did it.

  • Jim the Tool (unregistered) in reply to faoileag
    faoileag:
    lolwtfbbq:
    And which letter did you omit in the word "jug's"?
    Well, since Jim the Tool's original post ended as "captcha jugis. Did the teacher have big jug's?"... I buy an "i"! And I want to solve!

    captcha facilisis. facilisis is jugis' her sister ;-)

    You win a small chicken with gangrene! Congratulations! To claim your prize, please mail all your identity papers, cards and similar (including passport), as well as all your credit cards, to the following address...

  • (cs)

    Is this even feasible? I shall have to ask my expert network administrator.

  • dkf (unregistered) in reply to vt_mruhlin
    vt_mruhlin:
    We don't have problems with users of electricity running an extension cord between two outlets, do we? Because they can't
    You know why they can't? Because electricians make sure they can't. And yet such abominations still happen; never underestimate the power of ignorance coupled to determination...
  • The Balance (unregistered)

    Exploded students, quantified by volume.

  • (cs) in reply to Hovercross
    Hovercross:
    Neil:
    On the other hand, STP isn't a panacea:

    Accidentally create loop between two Gigabit switches and a megabit switch.

    Gigabit switches shut down their direct link to break loop.

    Not if STP is set up right on all three switches - in modern spanning tree, the path cost between each of the gigabit switches and the fast ethernet switch will be 200,000 and between the two gigabit switches will be 20,000 - this should lead to one of the switches breaking a connection between the FE switch and the gigabit switch, with there "where" depending on a whole host of factors, but primarily the switch that has been elected as the root bridge.

    If the megabit switch gets the to be root, then the gigabit link will get blocked. So set the priority on the gigabit switches to make sure the megabit switch does not get root, unless it can not see either of the gigabit switches.

  • (cs)

    I can see a problem with STP that has not been mentioned. Someone plugs in a cable and creates a loop. Unless there is some notification, nobody knows. Cabling can be messy enough as it is when everything is correct. (Why yes, there is a mess of cables behind my computer.) It could be much worse with extraneous connections, and who is going to regularly go through all of the cabling to check that each cable is needed?

    Sincerely,

    Gene Wirchenko

  • bob. (unregistered) in reply to GM

    My first experience involved AUI drops. I should go out and buy a lottery ticket. In all these years, this has never happened to me.

    But, it does explain why my desk at that company in Redmond had 8 RJ45 jacks and only one worked.

  • Jack (unregistered)
    bombings here, explosions there, and the odd RPG
    Seriously? Someone's still using RPG? That's not just odd, that's dangerous!
  • Meh (unregistered)

    This has happened to me too. There were two purple cables in the same spot and I only noticed the wrong one. Had to restart the switches.

    Not all networking equipment support STP, so it can't always be used.

  • Larry (unregistered)

    True story from the academic environment (translation: where the smartest person on the narrowest topic thinks he's also the smartest person on every other topic).

    Suddenly the network died in my lab. I heard cries of dismay from the corridor outside and went to investigate. All up and down the hall people were bemoaning the lack of compute.

    One guy burst out of his lab looking for blood. "Those bastards!" he nearly screamed. "They shut down the network just as I'm hooking up my new router!"

    It didn't take long for about 20 other people to inform him exactly who the "bastard" was.

  • Tom (unregistered) in reply to ¯\(°_o)/¯ I DUNNO LOL
    ¯\(°_o)/¯ I DUNNO LOL:
    I guess that explains why Slashdot is down this morning. Someone plugged a wire into two Ethernet ports!
    Slashdot is down because nobody cares anymore. The new owners have turned it into WTF.
  • Sam (unregistered) in reply to dkf

    I have a little bag of evil power cords, that do not leave my control and escape into the wild. One of them is a 110VAC gender bender...

  • (cs) in reply to Tom
    Tom:
    ¯\(°_o)/¯ I DUNNO LOL:
    I guess that explains why Slashdot is down this morning. Someone plugged a wire into two Ethernet ports!
    Slashdot is down because nobody cares anymore. The new owners have turned it into WTF.

    Beta downtime?

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