Showing posts from October, 2011

Cisco ASA, ESX/vSphere, and Duplicate IP’s

Summary:Windows (2003/2008/R2) and/or Linux VM’s added to a VLAN and continuously report duplicate IP’s and Windows assign themselves APIPA (Private Address).Symptoms:(Windows) 169.254.x.x Address shows up as (Preferred) when running ipconfig /all in command promptResetting Adapter pops up Duplicate IP Error.Changing VM Network to a dummy network and vm nic reset, causes issue to go away.Changing VM Network back to problem network clears issue until vm is reset or nic is reset.Resolution:Assuming the Cisco ASA is the cause, you can follow the below steps to rectify the issue:Login to the Security Appliance ASDMSelect Device SetupExpand RoutingSelect Proxy ARPDisable Proxy arp on the related interface (usually associated w/ your VLAN)Other command line method:sysopt noproxyarp <interface name>If Windows is the issue for some reason, you can do this:Start –> Run… –> RegeditFind this key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\ParametersInsert a new DWORD …