A network connection( NC) is characterized by the phases of connection establishment, data transmission and connection termination. In packet-oriented networks, the connection is established with a data packet whose address is the MAC addressof the intermediate system( IS).
The Intermediate System makes the decision to process the data packet or not. This is based on the routing capacity, the available quality of service( QoS) in relation to the required quality of service, and the available management information. Then the decision is made which network service (which protocol variant) is to be used for the data packet. The connection is terminated when either all data packets have been transmitted and the sending station sends a termination request or when an unrecoverable error situation occurs and the transmission must be aborted with an error message.
Data packets belonging to the established connection are forwarded transparently. During this process, the Intermediate System (IS) takes breaks as required. If a recoverable, i.e. temporary, error situation occurs and the reset function is supported, the transfer is carried out again from the restart point.