I am trying to implement NAC (by ForeScout) in our company.
Before we push automatic VLAN change upon user login (by ForeScout NAC device) into our production network, I am testing end-host behavior by changing VLANs manually from a CounterACT Manager Console. However end hosts are not getting a new IP address after I change their VLAN from CounterACT Manager Console. The work around to this problem is that we manually need to disconnect and reconnect Ethernet cable to the end host NIC for IP address change to take effect.
So to debug more into this, I changed VLAN manually from switch itself & observed that end host is still NOT able to get a new IP. Again this time I had to implement same workaround of disconnecting and reconnecting Ethernet cable to the end host for IP address change to take effect.
When observed on Wireshark, it shows that end host sends DHCP Discovery request for new VLAN only when I disconnect & reconnect the Ethernet cable attached to its NIC.
Before carrying out those tests I had made sure that NIC drivers were up-to-date on the end host.
How do we make end-host get a new IP address without disconnecting (& reconnecting) cable attached to its NIC? Has anybody seen this issue when NAC (Cisco or ForeScout) is implied ?