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Communications Programming Concepts

DLCTOKEN Device Manager Nodes

The token-ring data link control (DLCTOKEN) device manager operates between two or more nodes on the token-ring local area network (LAN) using IEEE 802.2 procedures and control information as defined in the Token-Ring Network Architecture Reference. Protocol support includes:

DLCTOKEN provides full-duplex, peer-data transfer capabilities over a token-ring LAN. The token-ring LAN must use the token-ring IEEE 802.5 medium access control (MAC) procedure and a superset of the IEEE 802.2 logical link control (LLC) protocol, as described in the Token-Ring Network Architecture Reference.

Multiple token-ring adapters are supported with a maximum of 254 service access point (SAP) users per adapter. A total of 255 link stations (LS) per adapter are supported and are distributed among active SAP users. Multiple ring segments can be accessed using token-ring network bridge facilities, with up to eight consecutive ring segments supported between any two nodes.

LLC refers to the manager, access-channel, and LS subcomponents of a generic data link control (GDLC) component, such as DLCTOKEN device manager, as illustrated in the DLCTOKEN Component Structure figure.

Each LS controls the transfer of data on a single logical link. The access channel performs multiplexing and demultiplexing for message units flowing from each LS and manager to the MAC. The DLC manager performs the following actions:


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