COTN1220_02_Network_Models.pdf

COTN 1220 – Data Communication Network Models DEFINITIONS Network – combination of hardware and software on which at least two nodes are connected, by a transmission medium, and are communicating. Hardware – physical equipment that carries signals from one point of the network to another...

COTN 1220 – Data Communication Network Models DEFINITIONS Network – combination of hardware and software on which at least two nodes are connected, by a transmission medium, and are communicating. Hardware – physical equipment that carries signals from one point of the network to another. Software – instruction sets that make possible the services that we expect from a network. LAYERED TASKS THE OSI MODEL International Standards Organization (ISO) – multinational body dedicated to worldwide agreement on international standards. Open Systems Interconnection (OSI) model – covers all aspects of network communications. Open system – set of protocols that allow two different systems to communicate. ISO is the organization. OSI is the model. THE OSI MODEL (cont.) The International Organization for Standardization (ISO) recognized there was a need to create a network model that would help vendors create networks that would work, compatible and interoperable with other networks. In 1984, the ISO released their networking model, OSI reference model. A reference model is a blueprint of how communications should take place. THE OSI MODEL (cont.) A mnemonic: All People Seem To Need Data Processing THE OSI MODEL (cont.) Peer-to-Peer Process THE OSI MODEL (cont.) Network support layers (1, 2 and 3) – deal with physical aspects of moving data from one device to another. (Hardware & Software) Layer 4 – links the two subgroups and ensures that what the lower layers have transmitted is in a form that the upper layers can use. User support layers (5, 6, and 7)– allow interoperability among unrelated software systems. (Software) THE OSI MODEL (cont.) Encapsulation 7 – APPLICATION LAYER Application layer is responsible for providing services to the user. 6 – PRESENTATION LAYER Presentation layer is responsible for translation, compression, and encryption. 5 - SESSION LAYER Session layer is responsible for dialog control and synchronization. 4 - TRANSPORT LAYER Transport layer is responsible for the delivery of a message from one process to another. 4 - TRANSPORT LAYER (cont.) 3 - NETWORK LAYER Network layer is responsible for the delivery of individual packets from the source host to the destination host. 3 - NETWORK LAYER (cont.) 2 - DATA LINK LAYER Data link layer is responsible for moving frames from one hop (node) to the next. 2 - DATA LINK LAYER (cont.) 1- PHYSICAL LAYER Physical layer is responsible for movements of individual bits from one hop (node) to the next. 1- PHYSICAL LAYER (cont.) Responsibilities Physical characteristics of interfaces and medium - type of transmission medium. Representation of bits – defines the type of encoding (how Os and I s are changed to signals). Data rate – number of bits sent each second. Synchronization of bits – sender and the receiver clocks must be synchronized. 1- PHYSICAL LAYER (cont.) Responsibilities (cont.) Line configuration – Point-to-Point or multipoint Physical topology – mesh, star, ring, bus and hybrid. Transmission mode – simplex, half-duplex, or full-duplex LAYERS SUMMARY TCP/IP PROTOCOL SUITE The layers in the TCP/IP protocol suite do not exactly match those in the OSI model. TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application. TCP/IP PROTOCOL SUITE (cont.) ADDRESSING Four levels of addresses are used in an internet employing the TCP/IP protocols: physical, logical, port, and specific. ADDRESSING (cont.) MAC ADDRESS (PHYSICAL ADDRESSES) Most local-area networks use a 48-bit (6-byte) physical address written as 12 hexadecimal digits; every byte (2 hexadecimal digits) is separated by a colon, as shown below: 07:01:02:01:2C:4B A 6-byte (12 hexadecimal digits) physical address. MAC ADDRESS (PHYSICAL ADDRESSES) Composed of 2 parts: Organizational Unique Identifier (OUI) – organizational unique identifier. Vendor assigned – alphanumeric identifier assigned by the vendor. OUI Vendor 07:01:02 07:01:02:01:2C:4B :01:2C:4B IP ADDRESSES (LOGICAL ADDRESS) Logical addresses are necessary for universal communications that are independent of underlying physical networks. A logical address in the Internet is currently a 32-bit address that can uniquely define a host connected to the Internet. No two publicly addressed and visible hosts on the Internet can have the same IP address. No two host on the same network can have the same IP address. 164.42.182.5 A 32-bit (4 octets) logical address. IP ADDRESSES (LOGICAL ADDRESS) (cont.) The physical addresses will change from hop to hop, but the logical addresses usually remain the same. PORT ADDRESSES In the TCP/IP architecture, the label assigned to a process is called a port address. A port address in TCP/IP is 16 bits in length. 110 A 16-bit port address represented as one single number. PORT ADDRESSES (cont.) SPECIFIC ADDRESSES Some applications have user-friendly addresses that are designed for that specific address. Examples: [email protected] – The recipient of an e-mail www.aguadilla.inter.edu – Universal Resource Locator (URL) WARRIORS OF THE NET https://youtu.be/PBWhzz_Gn10?si=920xtRa_y5lio46t