Editing IEEE 802.2 (section)

==Operational modes==
IEEE 802.2 provides two [[connectionless mode transmission|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 (network topology)|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 reduces 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 mode transmission|connectionless]] service. It supports point-to-point communication only.

Each device conforming to the IEEE 802.2 standard must support service type 1. Each network node is assigned an '''LLC Class''' according to which service types it supports:

{| class="wikitable"
!rowspan="2"| LLC<br/>Class
!colspan="3"| Supported Service Types
|-
!style="text-align:center;"| 1
!style="text-align:center;"| 2
!style="text-align:center;"| 3
|-
|style="text-align:center;"| I
|style="text-align:center;"| X
||
||
|-
|style="text-align:center;"| II
|style="text-align:center;"| X
|style="text-align:center;"| X
||
|-
|style="text-align:center;"| III
|style="text-align:center;"| X
||
|style="text-align:center;"| X
|-
|style="text-align:center;"| IV
|style="text-align:center;"| X
|style="text-align:center;"| X
|style="text-align:center;"| X
|}