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Networks Gigabit Link Fails over C5e Patch

Discussion in 'Hardware' started by Unicorn, 19 Apr 2013.

  1. Unicorn

    Unicorn Uniform November India

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    I am scratching my head on this, and it's complicated to explain so forgive me if this sounds confusing :rolleyes:

    I have three switches, two Dell 5324s (Gigabit, managed) and one new Cisco SG100D-08 (Gigabit, unmanaged) which is for the office.

    Dell #1 is the workshop switch. Dell #2 is the house switch. These are connected with an aggregated link over two good quality Cat5 cables. They're at opposite ends of the house and the runs are quite long, but I get great transfer speeds between them and the links are rock solid.

    I want to connect the new 8 port Cisco to the workshop switch so the office and workshop are on the same network - the house will be on a different VLAN. Basically, I want to use the Cisco to add another 7 ports to the workshop switch, buut upstairs in the office instead of in the workshop. Sounds easy, yes? It's not, apparently. I have connected the two switches together with two brand new patch cables so it looks like this:

    Workshop switch -> [patch cable] -> Patch Panel -> Office wall port -> [patch cable] -> Cisco switch...

    but they will not link. I even tried a pair of crossover cables at each end, but they still didn't link. The 5324 has auto sensing ports anyway so it shouldn't matter.

    I connected the Cisco to the Dell in the workshop with both a crossover and a straight through patch and they both worked fine. So, by a process of elimination we're down to a bad patch between the workshop panel and the office wall plate, right? Wrong. First I continuity tested the connection, then when that tested fine, connected my office PC to the wall plate with a C5 patch. It connects straight away at 1Gbps.

    So, anyone got any bright ideas why a PC would link to a gigabit port on the Dell but the little Cisco won't?
     
  2. RichCreedy

    RichCreedy Hey What Who

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    do you get the lights but no network access or nothing at all? I presume you checked different ports on the switch, and tried different patch cables
     
  3. Unicorn

    Unicorn Uniform November India

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    With the switch connected in the office I get no Link/Act lights, no network activity on any connected devices, no Link/Act lights on the corresponding port of the workshop switch. With the PC plugged into the same wall socket, full gigabit connectivity.

    With the Cisco 8 port plugged into the Dell switch right beside each other (no wall socket/patch) I get a full duplex gigabit connection and I can then plug devices into the Cisco and get full connectivity. I just can't get it to connect with the C5e patch between the workshop and office, which supports a connection with any other device but the Cisco switch.

    I have tried multiple ports on the hub (Dell) and spoke (Cisco) switches, multiple patch cables including some taken straight from their retail packaging and just cannot make it work. It's the most confusing problem I have come across in a long, long time!
     
  4. marlowdrummer

    marlowdrummer Member

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    I'm only just learning about networking so please ignore me if I am wrong or talking out my ****

    The Cisco connects to the Dell switch in the office OK? But not to the garage switch?

    Have you checked any VLANs or strange port configs on the workshop switch?

    I have seen QoS causing issues when connecting multiple brands of switches (Dell/Netgear rebrands, Xtreme, Cisco). Since the Cisco is unmanaged have you tried turning off QoS on the port you are connecting it to on the workshop switch as the Cisco has QoS priority built in?
    Having been a lurker for many moons I have read a lot of your posts and you know what you are doing so I might be going over old ground.
    One last option, have you compared both switch configs and in particular the port configs, just in case there is something slightly different between them?

    All the best, I'll be keeping an eye on his thread :)
    S.
     
  5. Unicorn

    Unicorn Uniform November India

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    In both cases I'm trying to connect to the same switch in the workshop, just in two different ways - connecting it through the Workshop -> office patch fails to link, physically taking it to the workshop and plugging it in with a short patch cable links straight away. This also happens when I physically take it to and plug it into the Dell switch in the house. That makes it sound like the Workshop -> Office patch connection is faulty, but when I connect the office PC through it, the PC connects at 1Gbps straight away.

    The 8 port Cisco is the office switch. I want it connected to the workshop to give me 7 ports on the business network in the office instead of the one I have with the wall plate - I did pull in two cables from the workshop to the office but one of them is damaged, so I'm trying to do this to allow connection of another PC, two network printers and an XBMC Pi in the office.
     
    Last edited: 20 Apr 2013
  6. marlowdrummer

    marlowdrummer Member

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    Sorry :) mis-read slightly....

    I put down office instead of house... but you have already tested that option. DOH!!!

    It does sound like the cable run is damaged somewhere and the PC is just a little less fussy.
    Possibly bad connection at the patch panel/bent pin?


    Again, sorry for not reading your post correctly, way too early on a Saturday morning ;)

    edit:
    Actually, when you are testing it at the Dell switch, are you connecting in to the same port that the cable run is fed from? If not, it still could be a QoS issue?
    Have you also tried using a different port on the switch for the cable run and a different port on the patch panel? Just to take those out of the equation?
     
    Last edited: 20 Apr 2013
  7. adam_bagpuss

    adam_bagpuss Have you tried turning it off/on ?

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    sounds like its either been patched wrong or there is a break in the line somewhere. If no link is established chances are its the line
     
  8. Unicorn

    Unicorn Uniform November India

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  9. adam_bagpuss

    adam_bagpuss Have you tried turning it off/on ?

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    it was too early :)
     
  10. marlowdrummer

    marlowdrummer Member

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    I was thinking more of a voltage drop rather than a total lack of continuity/connection. Hence the comment about the PC being less fussy.
    I'll defer to your experience and that you have tested this already.

    Sorry I couldn't help.
    S.
     
  11. RichCreedy

    RichCreedy Hey What Who

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    how long is the cable run from workshop to office? i'm betting as marlowdrummer, that the cisco is being fussy, can you nip to a local pc shop and pick up a cheap switch to test
     
  12. Picarro

    Picarro New Member

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    Otherwise, you could "recreate" the cable length and connections in your workshop and see if it is still fussy. Would rule out any bad connections in the wall pull.
     
  13. Unicorn

    Unicorn Uniform November India

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    It's a pretty long run; it goes from the office on the ground floor all the way to the top of the house through the attic, then straight down into the workshop in the basement through a cavity. I'd say it could be 100m or slightly more.

    I have a Dell 16 port 10/100 switch here which works fine in place of the Cisco. It's not gigabit though, so I want to get the Cisco one working.

    I'll get the Link-runner and remote from work on Monday and test the voltage drop and run distance. You're probably right, it is a long run and the Cisco is more than likely being fussy.

    I'm going to do that tonight. I have a spare box of C5 FTP which I'll split and test with.
     
  14. RichCreedy

    RichCreedy Hey What Who

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    the fact that the other switch works ok, suggests the cable is ok, but just too long for the cisco, I would be tempted to have another word with cisco, and see if they would be willing to swap it, and if the replacement doesn't work, change brand.
     
  15. MSHunter

    MSHunter Well-Known Member

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    Some basics I have picked up:

    Only the router should be running DHCP server, make sure the managed switched are not doing this as well.

    100m is over the limit for GB over Cat5e, for this distance cat6 is required. (cat5e max is 25m for GB) according to wiki.

    The fewer switches you use in a network the better. Ideally you should run one main switch in a home network.

    Otherwise you need to run the System like a Business network and that can become complicated. If I remember correctly (jump in if you know better please) it is server/switch related and has to do the the function of IP addresses and cross communication between switches.

    If at all possible I would suggest using one switch.
     
  16. Picarro

    Picarro New Member

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    You might actually need to do a new pull through the attic. Shouldn't be so hard though. Just tie one end of the new wire to the end of the old wire and start pulling!
     
  17. woody_294

    woody_294 Wizard Ninja :P

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    This may sound dumb but I've found this fault plenty of times causing a 100 link to not work where there is no 10 option. Try making sure the twists go all the way to the connector or backplate , taking them out even 5mm before can effect the signal
     
  18. play_boy_2000

    play_boy_2000 It was funny when I was 12

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    If it's over 100m, then you're going to have problems. Another switch may link up, but that doesn't mean you won't get errors. The simplest test is just take the cisco out to the workshop and test it there.

    If your run going from the workshop to the office goes past the house switch, you could just cut the run in two, set two ports on a different vlan and use it basically as a repeater.
     
  19. Unicorn

    Unicorn Uniform November India

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    Only my router is running DHCP server, the managed switches take care of the VLANs. As it stands, the network runs perfectly. Adding the 16 port unmanaged and putting more devices on it doesn't make a difference, the DHCP server still assigns it addresses and the network runs fine, but it's not a gigabit switch so it adds a bottleneck to the whole network.

    I'm not 100% sure the run is over 100m, but I'm positive it's over 25m. I will measure it with the Link-runner when I get it from work tomorrow and get an exact figure, but it's looking like I am going to have to replace it anyway.

    I do have only one switch for the home network. My home network and business network are linked by aggregation between the two switches, but they're the same physical network. It's absolutely impossible for me to run only one switch for both because there are 20 ports in the house and another 20 in the workshop. It is a small business network.

    I don't understand your comment about the fewer switches the better in a home network though - what difference does that make? Ports are ports...

    It is the most complicated pull you could ever possibly imagine. It runs through two attics (house is a split level bungalow), one void area and the basement. It took me an entire day just to get the first two in, and most of the runs in the house have been replaced with C6 now, but I left that one because it was such a PITA :grr: The only runs of FTP C5 that are left are between the two switches in the house & workshop (another complicated run) and the two between the workshop and office, one of which doesn't work properly. It does look like I'm going to have to re-do it, but I won't be able to until I have time off work in school during the summer. I might even have to take out a section of plasterboard wall to do it because the cables run down through horizontal studs in the wall between the kitchen and dining room.

    I didn't get a chance to replicate the long run with Cat5 in the workshop last night, I might do it tomorrow when I know the exact run length.

    Already checked that, thanks!

    Workshop is in the basement, not outside.

    I might have to cut the run in two like you said, but I'd rather replace it with Cat6 if I'm going to have to do anything.
     
    Last edited: 21 Apr 2013
  20. Unicorn

    Unicorn Uniform November India

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    Ok, according to the Fluke Linkrunner, the conductor length between workshop and office is 81m. Not as long as I first thought, but still quite a distance. It does a lot of zig-zagging through the two attics which also adds length. I went up today and had a look at it - when I replace it with a Cat6a run, I'll try to route it a bit more directly.

    Anyway, getting back to the point, I took a length of FTP C5e cable @ 85m, terminated it at both ends and plugged the Cisco directly into the Dell. It didn't link. Picky Cisco is picky! As a last resort, I forced a single port on the Dell to 100 Mbps operation and it linked straight away, so it does seem to be the voltage drop/run length that the Cisco doesn't like. For ****s and giggles, I cut 20m off the long cable that I'd made, re-terminated it @ 65m total length and connected it to a gigabit port on the Dell, and it linked at 1Gbps without hesitation. Obviously with the lower conductor quality and turns ratio, it doesn't get anywhere near 1Gbps transfer speeds, but it does link.

    So, I'll set aside a day during the summer to pull in some Cat6a between the office and workshop. Until then, I'll have to live with the 100 Mbps bottleneck.
     

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