In the ieee 802 reference model of computer networking, the logical link control llc data communication protocol layer is the upper sublayer of the data link. A space link is a communications link between a spacecraft and its associated ground system or between two spacecraft. The logical link control and adaptation layer protocol l2cap is layered over the baseband protocol and resides in the data link layer. It is further subdivided into two protocol sublayers. Nov 30, 2016 logical link control llc layer media access control layer logical link control pdf logical link control and media access control logical link control vs media access control llc vs mac llc. The structure and coding of logical link control llc addresses. The logical link control llc layer is one of two sublayers that make up the data link layer of the osi model. This is accomplished by the llc service access points saps for the services residing on network computers. Logical link control llc provides conventional data link protocol functions, such as error control and flow control.
Logical link control protocols definition sponsored by, powered by an online computer dictionary. The functions, features, protocol, and services of the logical link control llc sublayer, which constitutes the top sublayer in the data link layer of the isoiec 8802 lan protocol, are described. In the ieee 802 reference model of computer networking, the logical link control llc data communication protocol layer is the upper sublayer of the data link layer layer 2 of the sevenlayer osi model. The acl1 connection gives a parcel exchanged association between the expert and all dynamic slaves in the piconet.
The logical link control protocol allows multiplexed communications between two nfc forum peer devices where either peer can send protocol data units at any time asynchronous balanced mode. In a local area network lan, the protocol that is used to control the transfer of frames between data stations in the lan independently of how the propagation medium is shared. L2cap uses the concept of channel to separate sequences of packets passing between layers of the stack. The original standard developed by the institute of electrical and electronics engineers ieee in collaboration with the american national standards institute ansi was adopted by the international organization for. The logical link control and adaptation protocol l2cap is based around the concept of channels. Logical link control llc is one of two data link layer dll network protocol sublayers within the open system interconnection osi data communication model. This is a placeholder document used to collect feedback on the. See also control, control protocol, data station, frame, local area network, logical link, propagation medium, protocol, transfer. Also, there is a llc control field for delivery requests or services. This sublayer is responsible for the data transmission between. Ieee 802 logical link control university of auckland.
The logical link control llc address used by the protocols. Llc is located in the upper dll area of osi layer 2 above the physical layer phy of osi layer 1. Jan 18, 20 the lcl layer also identifies a line protocol, such as sdlc, netbios, or netware, and may also assign sequence numbers to frames and track acknowledgements. The physical layer itself maintains the continuous connection model, especially on the downlink, where there is continuous transmission. The function of the logical link control llc is to manage and ensure the integrity of data transmissions.
It accepts link service data units from the network layer and delivers link protocol data units to the mac layer and the several link service access points are. The logical link control and adaptation protocol l2cap takes data from the higher layers of the bluetooth stack and from applications and sends it over the lower layers of the stack. Llc2 is a connectionorientated layer 2 data link control protocol for sna over a lan. The mac module has a critical role in conserving network life by efficiently and fairly allocating medium access to the contending nodes. The acl1 connection gives a parcel exchanged association. The l2cap2 logical link control and adaptation protocol is a product module that typically lives on the host. Logical link control and adaptation protocol multiplexes upper layer data onto the single asynchronous connectionless acl connection between two devices and, in the case of a master device, directs data to the appropriate slave. As we have already mentioned, llc is the upper subset of the data link layer. This data link layer is divided into two sublayers. Today, we are going to talk about the llc layer in details. Logical link control and adaptation protocol specification 1 introduction this section of the bluetooth specification defines the logical link control and adaptation layer protocol, referred to as l2cap. Logical link control characteristics of llc not shared by other control protocols. The llcp link must be activated prior to running this scenario and the connectionoriented mode echo service must be in the unconnected state.
Logical link control llc is one of two data link layer dll network protocol sublayers within the open system interconnection osi data. Ibm originally designed llc as a sublayer in the ibm token ring architecture. Lte provides a packet switched model at the sap, but retains a circuit switched model at the phy. The llc provides data link layer links to services for the network layer protocols. Formal verification of logical link control and adaptation. Two address spaces are used for addressing within the llc sublayer. Verify that a data link connection can be established, a service data unit is received and sent back correctly and the data link connection can be terminated. Performance evaluation of a logical link control protocol for an atm air interface. Logical link control protocol the logical link control protocol allows multiplexed communications between two nfc forum peer devices where either peer can send protocol data units at any time asynchronous balanced mode. L2cap passes packets either to the host controller interface hci, or in a hostless system, l2cap passes packets directly to the link manager. The logical link control llc is an interface to the media access control mac layer. Second layer of the osi reference model data link layer or the ieee 802 reference model which divides data link layer into logical link control and medium access control layer. Similarly in 14, we have performed verification of the configuration in logical link control and adaptation protocol from bluetooth protocol stack. Service type 1, is a connectionless service with no establishment of a connection, and an unacknowledged delivery.
Dlc also is an abbreviation for digital loop carrier. The logical link control llc has several service types. The structure and coding of logical link control llc. Service type 2, is a connection logical service with an acknowledgement of delivery. Long term evolution protocol overview nxp semiconductors. The logical link control lcl layer is one of two sublayers of the data link layer in the open systems interconnection osi. L2cap provides connectionoriented and connectionless data services to upper layer protocols with protocol multiplexing capability, segmentation and reassembly opera.
An llc frame is called an llc protocol data unit lpdu, and is formatted as. Bluetooth security logical link control and adaptation. Both of these two sublayers are responsible for different functions for the data link layer. Prerequisites requirements cisco recommends that you have knowledge of these topics.
The data link layer is an interface between the network and physical layer. Aug 18, 2011 logical link control llc is one of two data link layer dll network protocol sublayers within the open system interconnection osi data communication model. The communication endpoints are called service access points sap and are addressed by a 6 bit numerical identifier. Each one of the endpoints of an l2cap channel is referred to by a channel identifier.
Protocol multiplexing is supported by defining logical channels. If the mac layer is responsible for the medium access then llc layer is responsible for the logical link control for the data link layer. The standards for local area networks lans are generally comprised of the physical layer, the medium access control mac sublayer, and the logical link control logical link control llc sublayer. Protocol architecture protocols defined specifically for lan and man metropolitan area network transmission address issues relating to the transmission of blocks of data over the network. Logical link control protocols white papers llc software. Channel identifiers cids are local names representing a logical channel end point on the device. Cisco recommends that you have knowledge of these topics.
We then look in more detail at medium access control and logical link control. Performance evaluation of a logical link control protocol for. The llc sublayer acts as an interface between the media access control mac sublayer and the network layer. Logical link control computer networking interview. Llc layer is also known as the logical link control. Protocol does not support any type field identifying the higher layer protocol being multiplexed above it. L2cap is layered over the baseband protocol and resides in the data link layer as shown in figure 1. The services required of, or by, the llc sublayer at the logical interfaces with the network layer, the medium access control mac. In ethernet and wifi networks, the data link layer is split into two sublayers. The logical link control lcl layer is one of two sublayers of the datalink layer in the open systems interconnection osi. Logical link control llc definition what does logical link control llc mean. L2cap must be able to distinguish between upper layer protocol s uch as the service discovery protocol, rfcomm, and telephony control. Bluetooth security logical link control and adaptation protocol.
805 148 676 605 1078 197 1475 137 931 1171 707 871 814 883 1563 109 384 886 721 1327 765 479 1064 144 684 441 1380 477 853 787 1504 1266 1418 745 200 1379 411 1303 1315 619 848 423 1292