Exam Cram: Chapter 2- The OSI Model and networking Protocol (Pt1)

TCP(IP) Model

Application layer, Transport Layer, Internet Layer and Network Interface Layer

Physical layer(1)

Identifies the network physical characteristics; the physical layer defines the voltage used, its frequency and at which the data operation. these characteristics dictate the speed a, bandwidth at what distance the media type can be used. Hardware-type of media, cable, connector, and pinout used to format the cable. Topology- the physical layer identifies which network model is being used; mesh, ring, star, bus, and hybrid are common. Protocols and technologies often used at the physical layer areUSB, Ethernet, DSL, ISDN, T-Carrier Links(T1andT3) GSM and SONET

Data-Link layer(2)

Is responsible for getting data to the physical layer. the data-link layer is responsible for error detection, error correction, and hardware address. Data grouped at this layer is called a frame. Media Access Control (MAC)Layer-is the physical or hardware addressed burned in the NIC. It controls access to the network media and Mac layer specification is included in IEEE 802.1 standard. Logical Link Control(LLC)layer is responsible for the error and flow-control mechanisms of the data-link layer. Protocols and Technology available at this layer includes; HDLC, L2TP, PPP, PPTP, STP, VLANs

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Physical Data link Network Transport Session Presentation Application

Network Layer(3)

Primary responsible for routing; providing the mechanism for moving data(packets-logical grouping of network layer) from one network to another.mechnisms functions through the software routing protocols provided by the components. network routes can be configured in two ways; Statically-where routes are manually added to the routing table. dynamic- routing protocols such as RIP(routing information Protocol) and OSPF(Open Shortest Path first) are used to assign routes. Other Network Protocols used at this layer are ARP, RARP, ATM, IS-IS, IPsec, and MPLS

Presentation Layer(6)

The basic function is to convert the data intended for or received from the application layer int another format. this way data can be read across the network amongst different devices. Common data formats include; Graphic files-JPEG, TIFF, GIF Text and data-translate data into different formats, ASCII and EBCDIC Sound and video-MPEG, MP3 and MIDI Another important function of the presentation layer is encryption- which is scrambling of data so that it can be read by anyone other than the intended recipient. + basic role of presentation (that of data format translator) is to encrypt and decrypt presentation, the cryptographic protocol is TLS or Transport Layer Security.

Transport Layer(4)

The basic function of the transport layer is to provide mechanisms to transport data between network devices. it sets up and maintain the connection between nodes(devices)It does this in 3 ways; Error checking-protocols are used at the transport layer to ensure data(packets are correctly sent and receive. Service addressing the transport layer ensures that data is passed to the right service at the upper layers of the OSI model.Segmentation-blocks of data need to be broken down into packets of manageable size for the lower layers to handle Protocols that operate at the transport layer are UDP-connectionless oriented, and TCP-connection oriented. the Transport layer is responsible for data-flow control- how the receiving device can accept data transmissions.two common methods of data flow control are; Buffering-data is temporarily stored and waits for the destination device to become available. +the issue can arise of the device transmits data faster than the receiving device can manage. Windowing-data is sent in groups of segments that require only one acknowledgment. + the size of the window determines how many segments are fit into one acknowledgment at a define session between the two devices.

Session Layer(5)

is responsible for managing and controlling the synchronization of data between applications on two devices.Like the transport layer, the session layer create and maintain connection for two devices on behalf of the application software. Protocols that operate at the session layer are; NetBIOS, NFS and SMB

Presentation Layer(7)

the function of the application layer is to take request and data from the users and pass them to the lower layers of the OSI model. the application layer defines the processes that enable applications to use network services Protocols use at the application layer are SSH, GBP, DHCP, DNS, NTP, RTP, SIP, SMTP, FTP, SMB, HTTP, HTTPS