What are the seven layers of the OSI model in order?
In the context of the Network layer, the process whereby a router consults a list of rules before forwarding an incoming packet. The rules determine whether a packet meeting certain criteria (such as source and destination address) should be permitted to reach the intended destination.
Layer 7 in the OSI model provides interfaces that enable applications to request and recieve network services.
Data frames with destination addresses that specify that all computers on a netowrk must read and process these frames.
A mathematical recipe that generates a specific value, called a checksum, based on a frames contents. The ________ is calculated before frame transmission and then included with the frame; on receipt, the ________ is recalculated and compared to the sent value. If the two agree, it's assumed that the data frame was delivered intact; if they disagree, the frame must be retransmitted.
Cyclical Redundancy Check (CRC)
Layer 2 of the OSI model is responsible for managing access to the networking medium and ensuring error-free delivery of data frames from sender to reciever.
Data Link Layer
The frame component that's the actual data being sent across a network. The size of this section can vary from less than 50 bytes to 16 KB, depending on the network type.
The process of stripping the header from a PDU as it makes its way up the communication layers before being passed to the next higer layer.
The process of adding header information to a PDU as it makes its way down the communication layer before passing to the next lower layer.
The representation of 0s and 1s as a physical signal, such as electrical voltage or a light pulse.
A process designed to regulate information transfer between a sender and a receiver. ____________ is often necessary when there's a speed differential between sender and receiver.
The basic unit for network traffic as it travels accross the medium. Data is broken into these smaller, more manageable pieces for faster, more efficient delivery.
Information added to the beginning of data being sent, which contains addressing and sequencing information.
Information added to the end of the data being sent in a frame; it generally contains error-checking information, such as CRC.
The internation standards-setting body that sets the worldwide technology standards.
Internation Organization of Standardization (ISO)
The upper sublayer of the IEEE Project 802 model for the data link layer. It handles error-free delivery and controls the flow of frames between sender and receiver across a network.
Logical Link Control (LLC)
The lower sublayer of the IEEE Project 802 model for the data link layer. It handles access to network media and mapping between logical and physical network address for NICs.
Media Access Control (MAC)
Frames that use a special destination address so that any somputer listening for this address can read and process the frame's data.
Layer 3 of the OSI model handles addressing and routing PDUs across specific internetworks in which sender and reciever must traverse multiple networks.
The family of ISO standards developed in the 1970s to facilitate functionality of networking services among dissimilar computers on a global scale.
Open Systems Interconnection (OSI)
ISO Standard 7498 defines a frame of reference for understanding netowrks by dividing the process of network communication into 7 layers.
OSI Reference Model
Layer 1, the bottom layer of the OSI model, transmits and receives signals and specifies the physical details of cables, adapter cards, connectors and hardware behaviour.
AT layer 6, data can be encrypted and/or compressed to facilitate delivery. Platform-specific application formats are translated into generic data formats for transmission or from generic data formats into platform-specific application formats for delivery to the application layer.
The IEEE effort taht produced the collection of 802 networking specifications and standards.
A unit of information passed as a self contained data structure from one layer to another on its way up or down the network protocol stack.
Protocol Data Unit (PDU)
A family of related protocols in which higer-layer protocols provide application services and request handling facilities, and lower-layer protocols manage the intricacies of layes 1 - 4 in the OSI model.
A software component taht intercepts requests for service from a computer and redirects requests that can't be handled locally across the network to a networked resource that can handle the request.
A network-layer service that determines how to deliver an outgoing packet of data from sender to receiver.
Logical interface points used to transfer infomation from teh LLC sublayer to the upper OSI layers.
Service Access Points (SAPs)
Layer 5 of the OSI model is responsible for setting up, maintaining, and ending ongoing sequences of communications (called sessions) across a network
Layer 4 of the OSI model is responsible for fragmenting large PDUs from the session layer for delivery across the network, inserting integrity controls, and managing delivery mechanisms to allow for error-free reassembly on teh receiving end of a network transmission.