Guide to Networking Essentials, Chapter 7
International Organization for Standardization (ISO)
The international standards-setting body based in Geneva, Switzerland, that sets worldwide technology standards.
maximum transmission unit (MTU)
The maximum frame size allowed to be transmitted across a network medium.
deencapsulation
The process of stripping the header from a PDU as it makes its way up the communication layers before being passed to the next higher layer. See also protocol data unit (PDU).
Logical Link Control (LLC) sublayer
The upper sublayer of the IEEE Project 802 model for the OSI model's Data Link layer. It handles error-free delivery and controls the flow of frames between sender and receiver across a network.
Open Systems Interconnection
(OSI) reference model ISO Standard 7498 defines a frame of reference for understanding networks by dividing the process of network of the layer above it and the services and data it needs from the layer below it. Communication into seven layers. Each layer is defined in terms of the services and data it handles on behalf
protocol data unit (PDU)
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.
Presentation layer
At Layer 6 of the OSI model, data can be encrypted and/or compressed to facilitate delivery. Platform-specific application formats are translated delivery to the Application layer. See also Open Systems Interconnection (OSI) reference model. Into generic data formats for transmission or from generic data formats into platform-specific application formats for
access control
In the context of the Network layer and routing, the process by which 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.
peer communication
In the layered approach, each layer on one computer behaves as though it were communicating with its counterpart on the other computer. This sending computer did. Means each layer on the receiving computer sees network data in the same format its counterpart on the
Physical layer
Layer 1, the bottom layer of the OSI model, transmits and receives signals and specifies the physical details of cables, NICs, connectors, and hardware behavior. See also Open Systems Interconnection (OSI) reference model.
Data Link layer
Layer 2 in the OSI model is responsible for managing access to the network medium and delivery of data frames from sender to receiver or from sender to an intermediate device, such as a router. See also Open Systems Interconnection (OSI) reference model.
Network layer
Layer 3 of the OSI model handles logical addressing and routing of PDUs across internetworks. See also Open Systems Interconnection (OSI) reference model and protocol data unit (PDU).
Transport layer
Layer 4 of the OSI model is responsible for reliable delivery of data streams across a network. Layer 4 protocols break large streams of data into also Open Systems Interconnection (OSI) reference model and protocol data unit (PDU). Smaller chunks and use sequence numbers and acknowledgements to provide communication and flow control. See
Session layer
Layer 5 of the OSI model is responsible for setting up, maintaining, and ending communication sequences (called sessions) across a network. See also Open Systems Interconnection (OSI) reference model.
Application layer
Layer 7 in the OSI model provides interfaces that enable applications to request and receive network services. See also Open Systems Interconnection (OSI) reference model.
encoding
Representing 0s and 1s as a physical signal, such as electrical voltage or a light pulse.
Media Access Control (MAC)
sublayer The lower sublayer of the IEEE Project 802 model for the OSI model's Data Link layer. It handles accessing network media and mapping between logical and physical network addresses for NICs.
