Network Time Protocol — Network Time Protocol is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
This is the top-most sublayer within the data link layer. It supports the medium access methods specified by the MAC sublayer below it. The LLC sublayer provides two types of service: Connectionless service - This simple service treats each frame as a separate entity.
Also known as datagram service, it provides minimal frame recovery and sequencing. Connectionless service is used most often when higher layer protocols perform error recovery and sequencing.
Connection-oriented service - This complex service attempts to provide error-free transmission by creating a logical connection to the receiving device before transmission begins. It provides support for sequenced delivery of data and error recovery.
|Windows Network Architecture and the OSI Model - Windows drivers | Microsoft Docs||External links The data link layer or layer 2 is the second layer of the seven-layer OSI model of computer network ing.|
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An example is Ethernet. The card contains a MAC unit, which: Encapsulates and unencapsulates frames for transmission across the cable Detects errors Implements access control algorithms The sublayer uses an integrated tap and transceiver unit that connects to a communications card installed in the server or workstation.
The firmware on the Ethernet card handles the electrical functions. A DTE waiting to transmit a frame must first receive the control token.
The Token-Ring communications card is connected to the physical network using a trunk coupling unit, which drives and receives signals to and from the cable. The Token-Ring device driver implements protocol functions while the firmware handles token and electrical functions.
SLR protocols collect routing information in multiple Token-Ring environments, so individual nodes on separate Token-Ring LANs can establish routes to other workstations or servers. Workstations and servers in Token-Ring networks broadcast packets across all routes to determine the routing address es of other nodes on the network.
When packets cross bridges to reach nodes on other Token-Ring LANs, the source ring and bridge numbers are added to the routing information field of the packet. When broadcast packets reach SLR-enabled destinations, the destination workstation or server extracts the SLR information and stores it for future use along with the neighbor's information.
When a message is sent back to the neighbor, the stored SLR for that neighbor is included in the Token-Ring frame. Each bridge on the path examines the SLR and uses it to send the packet to the next bridge specified in the SLR, until it reaches the neighbor destination.
Figure shows the progression of a broadcast packet across a Token-Ring network. This increases the efficiency of the network. This condition applies only if your server communicates across the bridge with other VINES servers and workstations.
Otherwise, source-level routing is not needed. Servers that act as bridges do not need SLR enabled to perform bridging functions for any of their Token-Ring cards.
A server needs SLR enabled only when the server is the originator or ultimate destination of packets that contain source-level routing information.
The servers handle SLR for the workstations. However, unnecessary broadcast traffic results. This lets workstations that use multiple network protocols access protocol-specific network traffic using a single LAN card.
The two sets of proprietary protocols exist in parallel stacks above the MAC driver. VINES supports only connectionless datagram -based services.
It uses its own and other industry standard protocols such as X.Logical Link Control sublayer The uppermost sublayer is Logical Link Control (LLC).
This sublayer multiplexes protocols running atop the Data Link Layer, and optionally provides flow control. The Data Link layer uses frames to transport data between layers.
Framing is the process of interpreting data that is either received or sent out across the network. The LLC Data Link sublayer is an extension of and is responsible for framing, error-detection, and flow control.
Logical Link Control sublayer The uppermost sublayer is Logical Link Control (LLC). This sublayer multiplexes protocols running atop the Data Link Layer, and optionally provides flow control. The Data Link Layer provides a means for exchanging data over a common local media..
The Data Link Layer performs two basic services: Allows the upper layers . Answer / guest. Answer: C Logical Link Control Sublayer - Acts as a managing buffer between the upper layers and the lower layers. Uses Source Service Access Points. The Network layer is where the frames of the Data Link layer become packets.
It can be described as the puberty of the OSI model. It can be described as the puberty of the OSI model. It is where the boys of the Data Link layer become men.