We are doing Dot1X authentication with Meraki Wireless and ISE. When the client connects using dot1x the authentication success message is sent to ISE however the IP address which it received after authentication is not sent. Now we understand that probably during authentication IP address might have not been assigned so we have to rely on Interim update.
The question is what is the size of packet for this interim update packet and does the interim update packet is being sent by AP for each clients which means number of clients multiplied is equal to number of interim updates.
Re: Client IP address not sent to Radius on connect
Correct - the IP addresss is not known at the point the client is being authenticated.
The RADIUS server sends back an ACCESS_ACCEPT message to the AP to say to let the client connect - and that is the end of the authentication process. There is nothing to send back the clients IP address.
You could potentially enable RADIUS Accounting - and that might send you the extra info you are after.