The
Logical Link Control is a sublayer of the
data link portion of the
Open System Interconnection reference model (
OSI Model). Defined in
IEEE 802.2, LLC is responsible for the identification and
encapsulation of upper-layer
protocols in a layer-2
frame. The information provided by an LLC
header contains instructions to the data link layer on what to do with a packet once it is recieved on a
destination host (hand it over to the
IP protocol on the
network layer, for example).
LLC headers are only added to
802.3 Ethernet frames, as the
Ethernet_II specification contained a built-in field designed to hold upper-layer protocol information. 802.2 frames can be identified by the
source and
destination SAP fields in their data link headers.