IEEE 802.5 Token Ring

• IBM
• Token SD AC ED one byte each

Field                        Size           
Start Delimiter               1            
Access Control                1            
Frame Control                 1           
Destination Address         2 or 6           
Source Address              2 or 6           
Data                       No limit            
Checksum                      4            
Ending Delimiter              1           
Frame Status                  1

Token Ring Control frames

Control              Name                      Meaning            
00000000            Duplicate Address Test     Test if two stations
                                               have same address           
00000010             Beacon                   Locate Breaks in the ring           
00000011            Claim Token                Attempt to become monitor            
00000100             Purge                     Reinitialize Ring            
00000101             Active Mnitor present     Issued periodically 
                                               by the monitor           
00000110            Standby monitor present    Announce Presence of
                                                potential Monitors

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Last Changed: 15 September 1995