IEEE 802.2 - Operational Modes

Operational Modes

IEEE 802.2 provides two connectionless and one connection-oriented operational modes:

• Type 1 is an unacknowledged connectionless mode for a datagram service. It allows for sending frames
  • to a single destination (point-to-point or unicast transfer),
  • to multiple destinations on the same network (multicast),
  • or to all stations of the network (broadcast).

The use of multicasts and broadcasts reduce network traffic when the same information needs to be propagated to all stations of the network. However the Type 1 service provides no guarantees regarding the order of the received frames compared to the order in which they have been sent; the sender does not even get an acknowledgment that the frames have been received.

• Type 2 is a connection-oriented operational mode. Sequence numbering ensures that the frames received are guaranteed to be in the order they have been sent, and no frames are lost.
• Type 3 is an acknowledged connectionless service. It supports point-to-point communication only .