Can't receive frames sent from a mainframe through wired LAN and wireless LAN in Windows Vista or later

Applies to: Windows 7 UltimateWindows 7 EnterpriseWindows 7 Professional

Symptoms


Consider the following scenario:
  • A mainframe server sends frames to a computer that is running Windows Vista or a later version over wired and wireless LAN. The network topology is as follows:
    Mainframe –-- Wired LAN  –--  Wireless AP  –--  Wireless LAN  –-- Windows 
  • An SNA-LLC protocol adapter is installed on the computer to receive the frames. 
  • During the bridging process from the wired LAN to the wireless LAN, the wireless AP does not encapsulate the frames in compliance with either Bridge-Tunnel Encapsulation Protocol or RFC 1042 Encapsulation Protocol. 
In this scenario, the SNA-LLC protocol adapter in Windows cannot receive the frames.


Cause


This behavior is by design.

A frame that is encapsulated in compliance with Bridge-Tunnel Encapsulation Protocol has the following data sequence:

  • MAC header
  • DSAP (0xAA)
  • SSAP (0xAA)
  • UI (0x03)
  • Ethernet Tunnel (0x00 0x00 0xF8)
  • The frame type
 

A frame that is encapsulated in compliance with RFC 1042 Encapsulation Protocol has the following data sequence:
  • MAC header
  • DSAP (0xAA)
  • SSAP (0xAA)
  • UI (0x03)
  • RFC 1042 OUI (0x00 0x00 0x00)
  • The frame type 


Therefore, the wireless network component of Windows Vista or later versions drops any frame that is not encapsulated by either of the two protocols.

Workaround


To work around this issue, encapsulate frames in compliance with one of the following protocols:
  • Bridge-Tunnel Encapsulation Protocol
  • RFC1042 Encapsulation Protocol