07-07-2016 12:35 AM - edited 07-05-2021 05:22 AM
Hi Team,
we are using AIR-CT5760 controller in our network, almost 800 users connected, but some users (only) getting IP conflict again and again, Kindly advise what could be the issue?
Regards,
Bala
Regards
07-07-2016 01:15 AM
What way is the DHCP scope setup , is the controller the only device giving out ip addresses in the network , usually duplicate ips come from 2 scopes giving out address same range or somebody has set static ips from the dhcp scope and not excluded them and then there also given out in dhcp causing duplicate ips in the network
07-07-2016 02:12 AM
WLC doesn't have any dhcp scope, we have a separate DHCP server,
07-07-2016 02:17 AM
so why do you believe the issue is with the controller if a server is giving out the dhcp ips , the controller would only pass the dhcp information it shouldn't alter it , ip conflicts come from dhcp issues generally
07-07-2016 02:27 AM
yeah understand dude, but some users getting disconnected from the network when they doing work in live network, they are telling that ""suddenly ip conflict messages is coming while working and not able to work continuously, whenever its coming we need to disconnect from network and connect, this is affecting the production""
Even we having mobility network.
07-07-2016 02:48 AM
I would be looking at the server as that's responsible for giving out the addresses not the wlc, check what addresses these users get when the conflict occurs are they supposed to be reserved/static addresses etc
once an address is duplicate on the network it can black hole half the traffic for that ip address
the network switches and wlc etc will just forward on what the server sends out
07-08-2016 12:01 AM
i checked dude, but these ip's not assigned by static and not reserved for anything,
i had disconnected that particular laptop and tried to ping, it is not ping and no one using this ip, i couldn't assume anything for this issue
07-08-2016 12:14 AM
Have you got the exact alert the users were receiving when the issue happened
Is there multiple scopes having the same issue duplicates been seen or is this all seen on just one scope
If all scopes are effected you could check its not a server issues by removing a scope and setting a temporary dhcp scope on one of your Cisco switches and see if you see the same behaviour while the dhcp is being sent fro the switch rather than the server as a test
If you put a wireshark on one the effected pcs and capture the traffic as well while the issue is happening it will give you a better idea of whats going on with the dhcp offers and requests or else debug on Cisco devices dhcp dhcp det
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