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Wired Networks Thread, Network Issue in Technical; I have a 12port HP 4500G that is connected via 2xLACP links to the core. From the 12 port HP ...
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    Network Issue

    I have a 12port HP 4500G that is connected via 2xLACP links to the core.
    From the 12 port HP 4500G are 2x HP 48 port 4500 switches (also via 2GB links) and 3x Wireless AP's. There are 4 or 5 vlans across the switches.

    Our clients in one of the rooms with the 48 port 4500 PXE boot their operating system (thinstation) over the network tftpboot.
    Regularly, a couple of times per day, the clients loose connection halfway through their boot. Once a citrix connection is established they are ok and don't loose connection.
    My first guess is that Citrix is just ok at dealing with flakey connections and tftpboot isn't (UDP??).
    Rebooting the 4500G temporarily fixes the issue for a couple of hours.

    hp network node manager tool detects nothing wrong with the 4500G (or the other switches). There is nothing obvious in the logbuffer.
    Can't see any signs of loops. I didn't notice any flooding of that VLAN.

    Where else should I look?
    Should I just get another switch?

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    twin--turbo's Avatar
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    Can you run a steady ping on it, and then spot if that drops out and see if there are any warnings from the switches..

    Enabling syslog and having a syslog server may also help.

    Rob

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    That's the bizarre thing - it doesn't seem to be dropping any ICMP data, just the tftp booting gets interrupted!?
    The tftpbooting is working elsewhere in the school just not attached to that switch. No recent config changes.

    I'll have another look at logs

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    glennda's Avatar
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    I have seen various things with HP switches in that they randomly decide to block a port but don't appear to tell you anywhere that they have done it (hence the reboot or re port works.

    Are they switches up to date firmware wise?

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    Quote Originally Posted by glennda View Post
    Are they switches up to date firmware wise?
    No. I meant to do that. Might give it a go but can't see it's going to help much - no network changes

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    Quote Originally Posted by CyberNerd View Post
    Rebooting the 4500G temporarily fixes the issue for a couple of hours.
    Do all clients have that disconnect at the same time? I´d suggest do setup a mirror port on the HP and wireshark everything. Perhaps you can see something within the datastream.
    (Also do a firmware upgrade: https://h10145.www1.hp.com/downloads...tNumber=JE057A , it´s HP and I´ve read too many strange things they fixed in some other switching series I have the last months/years...)

  7. Thanks to snoerre from:

    CyberNerd (14th September 2013)

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    Just realised it's actually a 4200G, not that it makes much odds.
    https://h10145.www1.hp.com/downloads...&prodSeriesId=
    I've just done a firmware update (from home!) and I'll see how that pans out on monday and look at the port mirroring if the firmware didn't help.

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    plexer's Avatar
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    Speak to HP support? one of the first things they'll ask you to do is to upgrade the firmware so the fact you've already done that is good.

    Ben

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    The firmware upgrade didn't help at all. I couldn't see anything obvious (to me!) in the wireshark port mirror so I swapped it out with an A5120 (JE73A).

    While I was unplugging it I noticed one of the PoE injector bricks that was plugged directly into the switch had a red 'fault' light on it - could this be responsible? I'll probably never know as I replaced that too!

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    Duke5A's Avatar
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    I had a similar problem last year. Our phone switches were on the same subnet as instructional machines (don't blame me, it was like this when I got here) and were dropping calls like crazy every morning. I setup a rolling packet capture on the subnet with Wireshark and set a 500MB limit. As soon as the problem cropped up again I went into the capture file and discovered a ton of broadcast traffic coming from a teacher machine in the lab down the hall. It turns out the teacher was starting classroom management software that uses broadcast traffic for student computer discovery. Moving the phone switches over to their own VLAN solved the issue.

    TFTP is connectionless and the slightest burp will cause it to drop packets.

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    m25man's Avatar
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    I just got one of these to play with,
    http://www.flukenetworks.com/enterpr...work-Assistant
    Just the thing for finding those types of issues.

  13. Thanks to m25man from:

    CyberNerd (21st September 2013)

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    glennda's Avatar
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    Quote Originally Posted by CyberNerd View Post
    The firmware upgrade didn't help at all. I couldn't see anything obvious (to me!) in the wireshark port mirror so I swapped it out with an A5120 (JE73A).

    While I was unplugging it I noticed one of the PoE injector bricks that was plugged directly into the switch had a red 'fault' light on it - could this be responsible? I'll probably never know as I replaced that too!
    Do these switches have any sort of basic intrusion detection?

    Are 4500 comware?

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    Quote Originally Posted by glennda View Post
    Do these switches have any sort of basic intrusion detection?

    Are 4500 comware?
    yes comware, I don't think they have any intrusion detections other than broadcast suppression to counter network storms.

    Anyhow, I replaced the switch and everything is fine now so I'll write this one up as dodgy hardware.

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    Quote Originally Posted by m25man View Post
    I just got one of these to play with,
    OneTouch
    Just the thing for finding those types of issues.

    Nice. Looks pricey.

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