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Wireless Networks Thread, Strange IP problem between wired printer and wireless clients - Possibly Meru related in Technical; Hi, We have 2 Brother HL-6050DN printers both connected to the network via Ethernet. One of the two printers suddenly ...
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    Question Strange IP problem between wired printer and wireless clients - Possibly Meru related

    Hi,

    We have 2 Brother HL-6050DN printers both connected to the network via Ethernet. One of the two printers suddenly stopped working back in November. You couldn't access its web interface, couldn't get a ping response and couldn't print to it. We started with all the usual troubleshooting for connectivity problems, but happened to notice that when you ping the printer instead of getting the expected response e.g. "Response from {Local IP}: Destination host unreachable." we were getting this:

    Pinging {Printer IP} with 32 bytes of data:
    Reply from {Printer IP}: bytes=32 time=3ms TTL=60
    Reply from {Meru Controller IP}: Destination host unreachable.
    Reply from {Meru Controller IP}: Destination host unreachable.
    Reply from {Meru Controller IP}: Destination host unreachable.

    Ping statistics for {Printer IP}:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)

    Every time you ping the printer you get one response and then the Meru WiFi controller responds with "Destination host unreachable". If I check my ARP cache I see the MAC address of the Meru WiFi controller for the printer's IP address. I contacted Meru support who asked me to send them some logs. I was told that the Meru controller has an ARP proxy feature but they were confused why it was responding for the IP of the printer (which is wired, not wireless) and were going to look into it further. Meanwhile we couldn't leave the printer out of action and got it working by changing its IP. As a test we then went to the second printer and temporarily put the "broken" IP address on it; It instantly stopped working with the same symptoms.

    For the next 3 weeks we carried on as normal and totally forgot about the problem. Then all of a sudden both of the printers stopped working again with the same symptoms. Meru support did some more investigating and eventually said that the IP addresses of the printers were being registered with the controller from the wireless interface (I.e. for a wireless client, not a wired client) meaning another client must be using the printers IP. They did mention that the controller should be flushing its arp cache to remove any invalid entries which it wasn't doing. They manually deleted the entries to get the printers working again for now.

    To give you a bit of background information; Our network used to be entirely DHCP with the exception of one small scope for servers, switches, pritners and iPads etc. Due to a requirement for a configuration we wanted with a previous web filter we then split the network into DHCP and static addresses. The 2 printers in question had their IP addresses changed so they were using one of the new static IP's. We have now recently changed our web filter and decided to go back to DHCP. As a temporary solution we left the printers on the same IP's and then created DHCP reserves for them (even though they are still statically addressed) to stop anything else using their IPs.

    One of the printers stopped working again yesterday morning. As usual we pinged the printer but this time got:

    Pinging {Printer IP} with 32 bytes of data:
    Reply from {Printer IP}: bytes=32 time=3ms TTL=60
    Request timed out.
    Request timed out.
    Request timed out.

    Ping statistics for {Printer IP}:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss)

    So I'm not sure if Meru have changed anything to stop the controller replying. Based on Meru suggesting a wireless client is using the same IP we then looked at the associated devices list on the Meru controller and actually found a client with the printers IP. The MAC address of the client told us that it was an apple device, and the associated AP told us roughly where in the school the device was. So thinking there was a problem with the DHCP reservation or something we checked all of the Mac Books and Apple TV's in that area but couldn't find anything with the MAC address we were looking for. This morning we noticed the MAC address was using a static IP which belongs to a staff iPad. We have checked the iPad and it's configured with a static IP; The teacher said the Internet stopped working on it yesterday (our DCHP addresses don't have direct internet access) but he hasn't changed any settings.

    So we are now confused why an iPad which has a static IP would suddenly decide one day to use a DHCP address (more importantly a reserved DHCP address) and then the next day go back to static. When you switch between static and DHCP the iPad forgets all of the static IP address settings, so the teacher would have had to re-enter them if he had changed it and he said he didn't. We're also confused why it only appears to be happening to the IP addresses used by these two identical printers and to our knowledge nothing else.

    Any help would be greatly appreciated.

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    I did once see a nokia phone with a broken wifi stack some how assume the ip of my core switch/router. That was a fun half hour running that one down. The user did confirm that their phone was flakey on any wifi he tried it on. We turned it off and have never looked back.

    Coincidentally (and this is weird...) the printer in the room of the person with the broken phone was a 6050dn!



    So now for a helpful (?) guess....

    Perhaps the printer is responding to the DHCP/ARP request from the device? Are they on the same Ethernet broadcast domain?
    Last edited by psydii; 5th March 2014 at 06:20 PM.

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    Hi psydii,

    Sorry for the delayed reply, I was on training yesterday so wasn't able to get on here.

    Very interesting that you had the same printer! They are on the same Ethernet broadcast domain, but it appears that the Meru controller is responding to the ARP request for the printer rather than the other way round.

    Thanks,

    Dan

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    I really am guessing, but if the first thing to happen was that the printer responded to a dhcp request or sent some sort of malformed ARP request just as a device was waiting for an IP address it might gave its ip to that device. If the device receiving the IP address was a wireless client this would then cause the Meru controller to respond to any packets subsequently sent intended for the printer.

    Bit of a long shot?

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