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Wireless Networks Thread, Unreliable networking in Technical; We have already. The excuse is, if we need more switches, they come and install and that's all. They insist ...
  1. #16
    ndart's Avatar
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    We have already. The excuse is, if we need more switches, they come and install and that's all. They insist on us taking out an expensive network management package with them. I think you are right. I think they should have documented it and also handed it over in a timely fashion. I have vented my concerns to little avail. We have ordered some transceivers and I have managed to download the manuals. I have configured a netbook with wireshark on it and I will attempt to connect this up to the switch to see what's going on. Later on in the week when (and if) we get the transceivers we will replace both up and downlinks to see what happens with that too. Severing the links will be interesting in itself I think....

    Thanks so much for the help so far, invaluable guys....I'll keep you informed...

    Quote Originally Posted by pete View Post
    If the company who installed the infrastructure didn't document anything or provide you with details of how to access it, vent extreme displeasure in their general direction with a view to someone coming onsite PDQ to a) document their work and do a proper handover b) diagnose the problem.

    Lack of documentation would also suggest that they didn't document it for their own reference (unless you have a maintenance agreement with them?).

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    ndart's Avatar
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    We think we will get another switch. If you have tried these the Async0 port does not connect! I have tested it with my Fluke tester and it reckons it is a short. Is that a faulty switch in your opinion.

    Quote Originally Posted by cpjitservices View Post
    hi, I'd try another switch to be honest this would be the best way to rule out your main switch and see if a loop occurs. I'd grab a cheap Cisco switch or a HP or something to try it - you could also keep it in your store cupboard as a spare.

  3. #18
    cpjitservices's Avatar
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    I would seriously consider replacing that switch. For a main backbone switch I'd be looking at something like Cisco or HP or Nortel.

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    SYNACK's Avatar
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    I think it is probably a combo of a weak switch and bad wireing. Some switches fail rather ungracefully when confronted with less than perfect wireing, cat5e that may have been fine for 100mbit can be unstable at 1GB especially if it is old or installed by primates. The better switches seem to handle this alright simply resetting the port or not failing out at all (Cisco, HP) where as the cheaper gear (D-Link) drops the port and leaves it disabled until the switch is rebooted.

    We have some issues with this at one of our schools where some epicly dodgey wireing by an external contractor which I beleive must be run wrapped around a power feed from the cabinet all the way to the ports will drop with our dirty DGS-1248T switches but are fine on higher quality switches.

    I don't know much about AT apart from the fact that they did used to be well respected a couple of decades ago and that our MoE has a bulk purchase deal with them which personally makes me very suspicious of their quality.

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    cpjitservices's Avatar
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    I would be changing that switch, It's the main core switch I would be changing it to something high end like Cisco, Nortel or HP. Leave all the other switches alone though and just change the core.

    We where using Nortel 5590's for our absolute core switches but now all the core switches are Cisco 3550's, these are also the switches which connect our other sites.

    YOu might be able to get a couple off ebay cheap if you don't have much if a budget.

  6. #21
    ndart's Avatar
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    Having laboured over this switch I have deduced that the ASYNC0 which should be active and has a static IP of 192.168.242.242 does not WORK!!! I have copied this from the hardware manual: Out-of-Band Ethernet Management Port
    The out-of-band 10/100/1000 Mbps Ethernet port is dedicated to management
    traffic on the AT-9900s switch. Use it for initial configuration and on-going
    management tasks. The default IP address for the port is 192.168.242.242 to
    allow remote access. This port is reserved for management only; the switch
    does not transmit frames between this port and switch ports.

    I have tested this with my Fluke tester and it comes back with an error and NO link light! Do I have to activate this port or something? There is nothing I can see in the instructions!

    Any ideas anybody? At this rate I am not going to be able to link a laptop to it to test it and configure it or use wireshark....am I missing something or is this port faulty?

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    do your issues only occur at certain times of the day? If so it's unlikely to be a loop.

    as previous posters have mentioned you can use wireshark to check if any clients are producing a lot of traffic epecially broadcast frames otherwise unplug things until the problem goes away.

    as for management you should be able to telnet or SSH to the IP address of the switch and log in that way. The out of band management probably hasn't been setup.

  8. #23
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    I agree with all you have said. However these checks I have completed by unplugging everything and plugging it all back in until the switching becomes excessive. Our network suppliers did this too and maintain that when they were plugging in the segments as soon as any of the segments started to be plugged in again the switching started to be excessive which IMHO points to the switch. Also, you are correct the port has not been set up it seems. Having said this on trying to set it up I cannot even get a link light let alone anything else. It seems the port is dead! Any ideas on that one.

    I appreciate the comments and support with this by the way and thanks for taking the time and effort to respond....

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    I hope I'm not being too patronising ;-), but... given what you have available to you (e.g. no documentation, no management of the switch and the fact that you have a very busy core switch) I'd approach this in a methodical and logical manner.

    If you've got a hub and spoke network topology, I'd do this:

    1. Start by unplugging all of the fibre uplinks - monitor the switch activity, has the problem gone away? If yes, go to step 3, if not, go to step 2.
    2. Unplug all devices from the core switch and reconnect them one by one (with a few mins gap inbetween each) this way if you've got a device that has a faulty NIC, or is sending out junk the switch will have a chance to start displaying 'poorly symptoms' again.
    3. Reconnect each remote cab one by one with a suitable gap inbetween each, until the problem is identified as existing again - then you can be reasonable sure the problem is associated with the most recently connected remote cab - trouble shoot that!

    Hope this helps.

  10. #25
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    HI,

    No your not being patronising at all and what you have suggested is a standartd procedure which the company in question has tried but I have not....

    I will be trying this one out myself soon I fear. We have now some new transceivers to try too....

    I'll keep in touch and many thanks for the help...

    Quote Originally Posted by pantscat View Post
    I hope I'm not being too patronising ;-), but... given what you have available to you (e.g. no documentation, no management of the switch and the fact that you have a very busy core switch) I'd approach this in a methodical and logical manner.

    If you've got a hub and spoke network topology, I'd do this:

    1. Start by unplugging all of the fibre uplinks - monitor the switch activity, has the problem gone away? If yes, go to step 3, if not, go to step 2.
    2. Unplug all devices from the core switch and reconnect them one by one (with a few mins gap inbetween each) this way if you've got a device that has a faulty NIC, or is sending out junk the switch will have a chance to start displaying 'poorly symptoms' again.
    3. Reconnect each remote cab one by one with a suitable gap inbetween each, until the problem is identified as existing again - then you can be reasonable sure the problem is associated with the most recently connected remote cab - trouble shoot that!

    Hope this helps.

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    Hi, to be honest if that port is for management only then like every other switch that port wont need any setting up, if it did then that would be a poor build of switch as you need this port to initially first time set it all up set ip's and vlans etc etc and setup telnet access, without this port your switch is not configurable. You should be able to plug in a console cable or rollover cable to that port to the serial port of your PC and access the switch via hyperterminal or by the specified IP.

    If fluke has detected a problem with that port then I would say that switch is fubared and personally I wouldn't put it anywhere near any of the production network it'd be in the a nearby skip, I'd seriously not waste your time and get another switch, if a console port on a cisco router or switch goes down unless telnet is enabled it's useless so I'm guessing with your switch it won't be that much different.

    Since no traffic goes through that port unplugging stuff and plugging it back in wont affect anything on that particular port as no traffic goes through it, it could be a CPU spike that stops access to that port in which case, try unplugging everything power it down wait 2 minutes power it back up and see if fluke still detects a fault with that port.

    Hope this helps buddy, good luck!

  12. #27

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    If the network company is a tad evil and want to keep you tied into their services they may well have disabled the hardware managment port and only be allowing managment of the switch through the ip interface. We had a managed services company that helpfully did that to a couple of schools that I ran across and it was rather the opposite of endearing when you needed to go through three layers of help desk to get a port fowarded on your own router. I would check with them to see if they have disabled it and if not RMA the thing.

  13. #28
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    Cheers mate that's really good adivice. I'll do this tonight me thinks...

    Quote Originally Posted by cpjitservices View Post
    Hi, to be honest if that port is for management only then like every other switch that port wont need any setting up, if it did then that would be a poor build of switch as you need this port to initially first time set it all up set ip's and vlans etc etc and setup telnet access, without this port your switch is not configurable. You should be able to plug in a console cable or rollover cable to that port to the serial port of your PC and access the switch via hyperterminal or by the specified IP.

    If fluke has detected a problem with that port then I would say that switch is fubared and personally I wouldn't put it anywhere near any of the production network it'd be in the a nearby skip, I'd seriously not waste your time and get another switch, if a console port on a cisco router or switch goes down unless telnet is enabled it's useless so I'm guessing with your switch it won't be that much different.

    Since no traffic goes through that port unplugging stuff and plugging it back in wont affect anything on that particular port as no traffic goes through it, it could be a CPU spike that stops access to that port in which case, try unplugging everything power it down wait 2 minutes power it back up and see if fluke still detects a fault with that port.

    Hope this helps buddy, good luck!

  14. #29
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    Thanks SYNACK. I'll play with the fluke tester tonight and if no go I will order a new switch I think, only a Cisco or HP. Also, I think I will contact the network company about the switch and Management Port too. Thanks

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    Latest UPDATE

    We successfully tested and reset the switch yesterday and found some interesting things:

    Even after isolating the switch from the network by removing ALL links and then just inserting ONE link with transceiver we started to get the rapid traffic. It didn’t seem to matter which link we plugged in the switch exhibited this issue. Also, during the exercise, the other 9924 below was continually exhibiting this rapid packet traffic transfer as usual and was NOT affected by the removal of all those segments! This is good news for one thing and maybe bad news for another!

    The good news is that I think this proves that there doesn’t appear to be anything looping on our network.

    The bad news is (I think) that the AT switches may be transferring bad packets and taking ports out instead of dealing with them in a timely fashion. It might be possible to configure the switch to do this if only I could only get the management ports to work on them; whether this port has already been set up and somehow disabled I don't know. In any case this may be a fault with both switches as I have tried to link to both without success! I have contacted the company to look into this and we'll wait and see what happens there I guess. For the next week I am doing power tests to verify a hunch I have about power surges. Postulating an idea that when a power surge or brownout occurs, although the switch in that segment is proteccted by a Smart UPS the client PC in that segment isn't. My idea is that maybe the spike or surge will generate a bad packet or two which will be sent to that switch, the switch cannot handle it so it stops the port recieving. Just an idea that fits the facts but an interesting one...

    Will keep all updated and many thanks to everyone for your commend and suggestions so far.

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