jhammond Posted February 3, 2014 Author Posted February 3, 2014 In this case all that is between the pc is the main switch. In regards to the arp-a question raised by David Tindall. I have set a static ip of 192.168.0.157 and performed arp-a and the mac address for 192.168.1.254 is 04-fe-7f-5a-9b-cb the static ip has then been set to 192.168.1.150 and i have performed arp-a and got the mac address for 192.168.1.254 as 00-1a-70-8d-ae-74 this is showing two different mac addresses. Weird!
Synkrox Posted February 3, 2014 Posted February 3, 2014 Whats the core switch and does RM do your filtering off-site or do you have a proxy on the network? Posting the config of the core switch might help if its managed? if you know it should be a flat network backup the config just in case and hard reset it perhaps?
SkreeM1980 Posted February 3, 2014 Posted February 3, 2014 this is showing two different mac addresses. Weird! Agreed Very Weird. Have you got anything odd connected that may be also grabbing that IP? Last time I saw similar we had a wireless AP and a router 'sharing' and IP address. What switches do you have, do you have management access to them (telnet ssh etc) You could do a MAC trace through the switches and see where the device 00-1a-70-8d-ae-74 is connected, and therefore what it is. According to Wireshark · OUI Lookup Tool it is a Cisco/Linksys Device
simpsonj Posted February 3, 2014 Posted February 3, 2014 Have you checked that DNS has a reverse lookup zone for that IP address range?
jhammond Posted February 4, 2014 Author Posted February 4, 2014 yes the DNS has a reverse look up zone for 192.168.1.x subnet
jhammond Posted February 5, 2014 Author Posted February 5, 2014 i have looked through all of my switches (Cisco sg200) and can not find the mac address anywhere.. All wireless devices are TP Link. or netgear.
jhammond Posted February 7, 2014 Author Posted February 7, 2014 Hi, I have performed the test as you requested and i can see that i have two different MAC addresses for my gateway router address when changing ip ranges. I have tried to locate this mac address, even unplugged the internet from the switch and then performed the arp -a test and i still get the default gateway ip address coming up with this odd MAC address that i cannot locate anywhere. I have downloaded a mac address scanner and this has given me the same results. any other ideas are much appreciated as I am all out now. My last thought is the switch. Could this be the cause of all this trouble?
SchoolsBroadband Posted February 7, 2014 Posted February 7, 2014 Hi, I have performed the test as you requested and i can see that i have two different MAC addresses for my gateway router address when changing ip ranges. I have tried to locate this mac address, even unplugged the internet from the switch and then performed the arp -a test and i still get the default gateway ip address coming up with this odd MAC address that i cannot locate anywhere. I have downloaded a mac address scanner and this has given me the same results. any other ideas are much appreciated as I am all out now. My last thought is the switch. Could this be the cause of all this trouble? possibly. Have you rebooted the switch? Sometimes their MAC tables can go screwy 1
Synkrox Posted February 7, 2014 Posted February 7, 2014 Yes. A while back I did suggest backing up your config and doing a hard reset on the switch, as you are on a flat network nothing to lose.
jhammond Posted February 7, 2014 Author Posted February 7, 2014 OK, I will backup the current config and do a hard reset on the switch on Monday evening so I don't take net network down during school hours. I will keep you all posted! 1
mac_shinobi Posted February 7, 2014 Posted February 7, 2014 possibly. Have you rebooted the switch? Sometimes their MAC tables can go screwy By MAC Tables as in routing tables etc or what do you mean ? Just curious
jhammond Posted February 18, 2014 Author Posted February 18, 2014 I have managed to fix the issue!!!!! I reset the main switch to factory defaults and this did not work; however i managed to find the port from the MAC address. I chased this back around the school and it lead me to a small switch cab that i did not know about (was not mentioned on the handover or networking diagram!) This was the Cisco Lynksys switch. Hard rebooted and did nothing, so managed to get onto the console of the switch; low and behold this had a static ip of 192.168.1.254. I changed this and the DHCP etc then updated the firmware and tested the 192.168.1.x range. all is now working!! Thank you all for your help in resolving this! 1
SchoolsBroadband Posted February 18, 2014 Posted February 18, 2014 Good work and you're more than welcome 1
mac_shinobi Posted February 18, 2014 Posted February 18, 2014 I have managed to fix the issue!!!!! I reset the main switch to factory defaults and this did not work; however i managed to find the port from the MAC address. I chased this back around the school and it lead me to a small switch cab that i did not know about (was not mentioned on the handover or networking diagram!) This was the Cisco Lynksys switch. Hard rebooted and did nothing, so managed to get onto the console of the switch; low and behold this had a static ip of 192.168.1.254. I changed this and the DHCP etc then updated the firmware and tested the 192.168.1.x range. all is now working!! Thank you all for your help in resolving this! Thanks for the update / feedback, may help someone else in the future
Network_Boy Posted January 22, 2015 Posted January 22, 2015 This is a lot of help. I've just taken over at a school who have supernetted in exactly the same way - changing from a subnet of 255.255.255.0 to 255.255.254.0 to double the number of IP addresses they can use. This was all working hunky-dory until we had loads of external headteachers in yesterday wanting to get online on their devices for some training. Devices receiving IP addresses via DHCP on the old 10.36.4.* range work fine both wired and wirelessly. Devices receiving IP addresses via DHCP on the new 10.36.5.* range would only work via a wired connection, but NOT wirelessly. We have an 8 hour IP lease here, so all the nice old 10.36.4.* addresses were taken when the headteachers rocked up in the afternoon for their training. None of them could get online. Very embarrassing. This was doing my nut until I deduced that it must be something to do with the wireless controller configuration (they have a very nice, reasonably new Meru network). The external company who came in before I started to do the IP range extension must have left out the wireless controller configuration, as it looks like the controller is still on the 255.255.255.0 subnet. The option for me to change the subnet mask on the wireless controller is greyed out for me, so I am currently in the process of getting support from Meru to sort this out. Will post back when it's fixed. Hope this is useful for someone if they ever have the same issue!
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