Same layer interaction on different computers
The two computers use a protocol to communicate with the same layer on another computer. The protocol defined by each layer uses a header that is transmitted between the computers to communicate what each computer wants to do.
Adjacent layer interaction on the same computer.
On a single computer one layer provides a service to a higher layer. The software or hardware that implements the higher layer requests that the next lower layer perform the needed function.
List the layers of the OSI model.
Interfaces between network and application software. Includes authenticatin services.
Defines format and organization of data. Includes encryption.
Establishes and maintains end-to-end bidirectional flows between end points. Includes managing transaction flows.
Provides a variety of services between two host computers including connection establishement and termination, flow control, error recovery, and segmentation of large data blocks inter smaller parts for transmission.
Logical addresssing, routing and path determination.
Formats data into frames appropriate for transmission onto some physical medium. Defines rules for when medium can be used. Defines means by which to recognize transmission errors.
Defines electrical, optical, cabling, connectors and procedural details required for transmitting bits represented as same form of energy passing over a physical medium.
List the benefits of a layered network model
(See notes for full definitions)
- Less complex
- Standard interfaces
- Easier to learn
- Easier to develop
- Multivendor interoperability
- Modular engineering
OSI layer compared to TCP/IP (4 and 5 layer)
- OSI TCP/IP 4layer TCP/IP 5layer
- 7. Presentation
- 6. Session
- 5. Application Application Application
- 4. Transport Transport Transport
- 3. Network Internetwork Internetwork
- 2. Dataling Datalink
- 1. Physical Network Access Physical
Adjacent layer interaction
The general topic of how on one computer, two adjacent layers in a networking architectural model work together, with the lower layer providing services to the higher layer.
On a computer that receives data over a network, the process in which the device interprets the lower-layer headers and, when finished with each header, removes the header revealing the next higher PDU.
The placement of data from a higher layer protocol behind the header (and in some cases between a header and a trailer) of the next lower layer protocol. For example an IP packet cold be encapsulated in an ethernet header and trailer before being sent over and Ethernet.
A term refering to the datalink header and trailer, plus the data between the header and trailer
A generic term refering to any set of protocols and standards collected into a comprehensive grouping that, when followed by the devices in a network, allows all the devices to communicate. Examples include TCP/IP and OSI.
A logical grouping of information that includes the network layer header and encapsulated data, but specifically does not include any headers and trailers below the network layer.
Protocol Data Unit (PDU)
An OSI term to refere generically to a grouping of information by a particular layer of the OSI model. More specifically an Lx PDU would imply data and headers as defined by Layer X.
Same layer interaction
The communication between two network devices for the purpose of the functions defined at a particular layer of a networking model with that communication happening by using a header defined by the layer of the model. The two devices set values in the header, send the header and encapsulated data, with the receiving device interpreting the header to decide what action to take.
In TCP, a term used to describe a TCP header and its encapsulated data. (Also called a L4PDU). Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segments. In Ethernet, a segment is either a single Ethernet cable or a single collision domain (no matter how many cables are used.)