3Com WX4400 3CRWX440095A, WXR100 3CRWXR10095A manual Understanding Sessions Roaming Users

Understanding the Sessions of Roaming Users 161

Understanding the

Sessions of

Roaming Users

Requirements for Roaming to Succeed

When a wireless client successfully roams from one MAP to another, its sessions are affected in the following ways:

„The WX treats this client session as a roaming session and not a new session.

„RADIUS accounting is handled as a continuation of an existing session, rather than a new one.

„The session with the roamed-from MAP is cleared from the WX, even if the client does not explicitly disassociate from the MAP and the IEEE 802.1X reauthentication period has not expired.

Roaming requires certain conditions and can be affected by some of the WX switch’s timers. You can monitor a wireless client’s roaming sessions with the display sessions network verbose command.

For roaming to take place, the roaming client must associate or reassociate with a MAP in the Mobility Domain after leaving an existing session on a different MAP in the Mobility Domain in one of the following states:

„ACTIVE — The normal state for a client that has left radio range without sending a request to disassociate.

„DEASSOCIATED — The state of a client that has sent an 802.11 disassociate message, but has not roamed or aged out yet.

In addition, the following conditions must exist for roaming to succeed:

„Mobility Domain communications must be stable.

Generally, the communications required for roaming are the same as those required for VLAN tunneling. A client can also roam among ports on a WX when a Mobility Domain is inaccessible or not configured.

„Client authentication and authorization on the roamed-to MAP must be successful on the first attempt.

If authentication or authorization fails, MSS clears the client session. Depending on when the failure occurs, roaming can be disqualified or delayed.

„The client must use the same authorization parameters for the roamed-to MAP as for the roamed-from MAP.

If the client changes its encryption type or VLAN name, MSS might record a new session rather than a roamed session.