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Beginner

Major Dhcp issue on cisco switch Please help !!!

Hi Experts,
One of  our Remote sites has Cisco 2811 router and 3650 switch. The switch provides switching and DHCP features to all client's PCs.
Please see attachment files for more details.
Problem:
After DHCP lease time expired (10 hours), some of the PCs (Windows 7) at the Remote site received Windows popup says IP duplicated. Then, network connectivity of the PC was disconnected. After rebooted the PC, then its network connectivity was back to active state.
There was no issue when all the PCs were set to static mode.
Please see the attached configuration of Router and Switch.
Thank you very much

2 ACCEPTED SOLUTIONS

Accepted Solutions
Highlighted

That's strange that usually fixes the duplicate IP problem

How about putting the DHCP server on the router instead?

what do you get when you do a "show ip dhcp conflict" command

also can you share the "show ip dhcp pool" command

Richard

View solution in original post

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Hello,

I see your configuration and i see the next:

no ip dhcp ping packets
To specify the number of packets a Dynamic Host Configuration Protocol (DHCP) server sends to a pool address as part of a ping operation, use the ip dhcp ping packets command in global configuration mode. 

I think this is your problem, your dhcp server don´t ping for assignated ips.

If you have a rogue Dhcp server (This isn't the case, bacuse the issue was resolved put the dhcp server in the router) you can configure DHCP snooping.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/snoodhcp.html

View solution in original post

6 REPLIES 6
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Frequent Contributor

Hi you most probably need to enter the following command on all access ports on the 3650

"nmsp attachment suppress"

Network Mobility Services Protocol(NMSP) is really used for tracking wireless clients as they connect to different Acess points, but it caused problems with hard wired devices, I suspect this problem has been fixed in later 3650 IOS

HTH

Richard

Highlighted

Hi Richard,

Thanks for your reply. I tried the command you suggested but it did not help. The issue is still there. Any other recommendation.

Thank You.

Kind Regards

Highlighted

That's strange that usually fixes the duplicate IP problem

How about putting the DHCP server on the router instead?

what do you get when you do a "show ip dhcp conflict" command

also can you share the "show ip dhcp pool" command

Richard

View solution in original post

Highlighted

Thanks Richard for your help. Yes the issue is resolved now after putting the DHCP server on the router.

Highlighted

Hello,

I see your configuration and i see the next:

no ip dhcp ping packets
To specify the number of packets a Dynamic Host Configuration Protocol (DHCP) server sends to a pool address as part of a ping operation, use the ip dhcp ping packets command in global configuration mode. 

I think this is your problem, your dhcp server don´t ping for assignated ips.

If you have a rogue Dhcp server (This isn't the case, bacuse the issue was resolved put the dhcp server in the router) you can configure DHCP snooping.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/snoodhcp.html

View solution in original post

Highlighted
Beginner

Hi Rohit,

Adding to what Mr. Richard. Do you have windows desktop operating system lower than windows VISTA? If yes then have a look at this URL.

http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/8021x/116529-problemsolution-product-00.html

I encounter that same issue at one client and had to use Microsoft DHCP server instead. But they were using windows 7.

HTH.

Regards,

Terence