Client Roaming parameter while using DHCP Option 82

[CiscoWiFiGuy]

Hello Team,

I just want to know little more on dhcp option 82 side information . Currently AP name and SSID is being used in network to update client details over EOGRE Tunnel .

So as client is requesting IP from DHCP server ,initially these 2 parameters will be used for DHCP Handshakes or DHCP Ip assignment.

I just want to know how those updates will be passed over to other access points via when client is roaming from 1 access point to other or moving from one controller to other.

I got few documentation which are talking about option 82 but not specifically in terms of roaming.

My understanding is as long as client has the IP Lease and its not expired , client will have roaming so anyone can please let me know in deep what will happen at background.

Thanks

[balaji.bandi]

Option 82 give additional security in terms of DHCP :

https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_010110010.html

If you looking client Mobilty what happends on the background below blog is good start :

https://mrncciew.com/2013/03/16/wireless-mobility-basics/

[Arshad Safrulla]

The client sends a DHCP Discovery packet. Then the WLC receives the packet from AP, adds option82 (containing information about the SSID name=remote id and AP name=circuit id) and then transmits it to the EOGRE headend over the tunnel. The headend now received the DHCP Discovery from the client with option 82 info. The headend is configured to perform end user authentication and for this it uses an external RADIUS server. When sending a query to the RADIUS server, the router will include information about the option82 in the authentication packet. The RADIUS server should authenticate the end-user based on information included in option82. Now radius server knows which AP and SSID client is connecting to. But inorder to get the information when the user is roaming across AP’s you need to have accounting configured (AAA and accounting proxy under the tunnel parameters). Each time user roams to a new AP, based on the DHCP behavior accounting messages will be exchanged and this will contain circuit and remote id’s (ap name and ssid name)