Are your APs in Flexconnect mode and if so do you have flex connect arp cache enabled? If so you might want to try disabling ARP caching.
http://www.cisco.com/c/en/us/td/docs/wireless/controller/8-2/config-guide/b_cg82/b_cg82_chapter_010010101.html https://quickview.cloudapps.cisco.com/quickview/bug/CSCuy29143 What model of card are the devices connected to on the Nexus 7ks? And how many MAC addresses are in the MAC address table (the layer 2 table, not the ARP table)? (check with "show mac address count”) We saw different symptoms when the MAC MAC address table was exceeded but it is still worth checking to eliminate as a possible problem. > On Feb 27, 2017, at 9:10 PM, Shayne Ghere <[email protected]> wrote: > > I’m reaching out since we just started having problems with users complaining > about getting messages on their Mac’s about a duplicate IP address on the > network. > > When looking in the ARP table of the Cisco Nexus switches, the mac address of > their computer isn’t in there, however the IP address their machine has is > owned by another mac address even though both the Controller and Prime > doesn’t see that machine associated. > > I came across an article that the Arp Cache Timeout on the 6509’s was 300 > seconds, but the Nexus (7K) has bumped it to 1500-1800 seconds now. That > jives with what I’m seeing as the disassociation time of the original > machine, and the duplicate message (within 20-25 minutes). > > The Arp-Cache timeout on the Controller is set for 1800 seconds, and was > configured that way since September 2016 (Cisco WLC 8540) with no problems. > > This problem just cropped up within the past two weeks and is gaining steam. > Out of the 30 or so devices, 38 are Mac’s and the other two are Windows 10 or > Microsoft Surface tablets. > > This is only happening on our Secure 802.1x wireless network. > > We use Microsoft NPS for Radius and Linux DHCP/DNS. > > If anyone else is experiencing these issues, or could point us in the right > direction, I would greatly appreciate it. Our Server/Radius team is fairly > sure it’s not on their end, yet after talking with Cisco, I’m fairly positive > it’s not the Controller/Wireless. Not finger pointing, just asking for some > advice. > > Thanks in advance! > Shayne > > ---------------------------------- > T. Shayne Ghere > Bradley University > Wireless/Lan Network Engineer > 1501 W. Bradley Ave, Jobst 224A > (309) 677-3094 > [email protected] > ---------------------------------- > UPCOMING OUT OF OFFICE > > > ********** Participation and subscription information for this EDUCAUSE > Constituent Group discussion list can be found at > http://www.educause.edu/discuss. --- Bruce Curtis [email protected] Certified NetAnalyst II 701-231-8527 North Dakota State University ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/discuss.
