OSI (Open Systems Interconnection) Reference Model
Physical Medium Attachment, Accommodating Various Possibilities in the Medium: Will an external transceiver (MAU) be used to connect to the medium? How many pins do the connectors have and what is each pin used for? Transmission Technique: determines whether the encoded bits will be transmitted by baseband (digital) or broadband (analog) signaling. (d) If the data that is sent has problems, the destination requests the source for retransmission by acknowledging only packets that have been received and are recognizable
These issues have been cleaned up through the publishing of annexes to the original OSI Model which makes protocols such as IGML and ICMP defined as layer management protocols for the Network Layer. The baseline OSI documentation does not address the technology or possibility of tunneling, but it is addressed through extensions to the model such as with the transport layer gateways defined within the International Standardized Profile network
Comparison
(Source: Both models assume that packets are switched.- Basically this means that individual packets may take differing paths in order to reach the same destination
The OSI Reference Model
Thus, in addition to the usual problems of figuring out where to send data to and getting it formatted and converted to and from 1's and 0's, we have the problem of how to allocate the shared medium to the various users: Media Access Control (MAC). The routing tables are constructed and updated by the routers acting autonomously, using a set of signaling protocols which operate completely independently of user data, though they use the same IP protocol to send routing messages
Despite their architectural differences, both models have interchangeable transport and network layers and their operation is based upon packet-switched technology. The Open Systems Interconnection Basic Reference Model (OSI Model) is an abstract description for network protocol design, developed as an effort to standardize networking
And because you probably have a lot of different people working on building your house, such as framers, electricians, bricklayers, painters, and so on, it helps if they can all reference the same plan. Which OSI layer defines the functions of logical network-wide addressing and routing? Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 Layer 6 Layer 7 Which OSI layer defines the standards for cabling and connectors? Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 Layer 6 Layer 7 Which OSI layer defines the standards for data formats and encryption? Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 Layer 6 Layer 7 Which of the following terms are not valid terms for the names of the seven OSI layers? (Choose two answers.) Application Data link Transmission Presentation Internet Session 2
The first layer is the most concrete, as it deals with the actual hardware of networks, and the specific methods of sending bits from one device to another. The seventh and highest layer is the application layer, which deals with high-level applications employed by users: both end users and the operating system software
The physical layer uses the appropriate wireless protocol (for example, the appropriate direct sequence spread spectrum modulation or DSSS) to communicate the request over the air wirelessly to the physical layer on the other network. Wireless APs and wireless stations exchange three types of frames, each with the following functions: Data frames carry user payload data (the hamburger) between different wireless network nodes
In fact, it's pretty much impossible to read a lot about networking without encountering discussions that presume at least some knowledge of how the OSI Reference Model works. The existence of the model makes it easier for networks to be analyzed, designed, built and rearranged, by allowing them to be considered as modular pieces that interact in predictable ways, rather than enormous, complex monoliths
Internet layer pack data into data packets known as IP datagrams, which contain source and destination address (logical address or IP address) information that is used to forward the datagrams between hosts and across networks. Network Access Layer defines details of how data is physically sent through the network, including how bits are electrically or optically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted pair copper wire
Most of these application processes builds on what it needs and assumes only that an underlying transport mechanism (datagram or connection) will be provided. The standard specifies the syntax and the allowable values for the high-order part of the address - the Initial Domain Part (IDP), which consists of the Authority and Format Identifier (AFI) and the Initial Domain Identifier (IDI) - but specifically eschews constraints on or recommendations concerning the syntax or semantics of the domain specific part (DSP)
The distribution of bits - how many form the network number, and how many are therefore left for the host number - can be done in one of three different ways, giving three different classes of IP address 32. ESs and ISs send and receive these routing updates and use the information that they contain (and information that may be available from the local environment, such as information entered manually by an operator) to modify their routing information base
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