Chapter2: analog and digital signals can take one of two forms: 1. periodic 2. nonperiodic Periodic analog signals can be classified as: 1. simple 2. composite A sine wave is represented by three parameters: 1. Peak amplitude 2. Frequency 3. Phase. An optical transmission system has three key components: 1. light source 2. transmission medium 3. the detector. radio Apps: 1. AM and FM radio, 2. TV 3. cordless phones 4. paging the wavelength: The distance between two consecutive maxima (or minima) infrared Advantage: 1.prevents interference between systems in adjacent rooms. infrared Disadvantage: 1. cannot use for long-range communication or outside a building due to sun s rays. microwave problem: 1. Line-of-sight (curvature of the Earth; obstacles) 2. Cannot penetrate walls satellite characteristics: 1.Similar to terrestrial microwave except the signal travels from a ground station on earth to a satellite and back to another ground station. 2. Satellite receives on one frequency, amplifies or repeats signal and transmits on another frequency 3. Satellite is relay station 4. Television 5. Long distance telephone 6. Private business networks
Chapter3: functions of data link layer: 1. Providing a well-defined service interface to the network layer. 2. Dealing with transmission errors. 3. Regulating the flow of data so that slow receivers are not swamped Data Link layer Design Issues: 1. Services Provided to the Network Layer 2. Framing 3. Error Control 4. Flow Control three framing methods: 1. Byte count. 2. Flag bytes with byte stuffing. 3. Flag bits with bit stuffing. detection methods: 1. parity check 2. cyclic redundancy check 3. checksum parity check pros: 1. The most common and least expensive. 2. Simple or Two Dimensional. Flow control schemes : 1. simplest 2. stop-and-wait 3. stop-and-wait ARQ 4. go-back-in ARQ 5. selective repeat ARQ noiseless channels: 1. Simplest Protocol 2. Stop-and-Wait Protocol noisy channels: 1. Stop-and-Wait Automatic Repeat Request(ARQ) 2. Go-Back-N ARQ 3. Selective Repeat ARQ *للمراجعه فقط مهمه عشان نفهم تشابتر ٣ احفظو الليرز وترتيبها وال هي محذوفه* Chapter4:
The seven layers of the OSI model are: 1. Application (layer 7) 2. Presentation (layer 6) 3. Session (layer 5) 4. Transport (layer 4) 5. Network (layer 3) 6. Data link (layer 2) 7. Physical (layer1) upper layer data: 1. Application (layer 7) 2. Presentation (layer 6) 3. Session (layer 5) Network applications: 1. mail 2. web 3. file transfer Presentation Layer Provides: 1. Encryption and Decryption 2. Compression Session Layer Provides: 1. Controls dialogs between computers Transport Layer Provides: 1. Reliability 2. Flow control 3. End-to-end error recovery 4. end_to_end connection Network Layer provides: 1. Routing of packets Data Link Layer provides: 1. Connection between hosts on the same network 2. Hop to hop communication Physical Layer: 1. Describes electrical and physical specifications for devices 2. Reliability 3. Flow control Communications involve three agents: 1. Applications 2. Computers 3. Networks
TCP/IP Protocol suite: 1. application protocols 2. transfer protocols 3. network protocols 4. data link protocols 5. physical protocols TCP/IP protocol layers are: 1. Hardware devices/physical layer 2. Network Interface/Data link layer 3. Internet layer/network Layer 4. Host-to-host/transport layer 5. Application layer the internet protocol (IP) functions : 1. Defines the format of the packet, called a datagram at the network layer. 2. Defines the format and the structure of addresses used in this layer. 3. Responsible for routing a packet from its source to its destination, which is achieved by each router forwarding the datagram to the next router in its path some predefined protocols in the application layer: 1. HTTP 2. FTP 3. SMTP Chapter5: There are three restrictions in classless addressing: 1. The number of addresses needs to be a power of 2. 2. The mask needs to be included in the address to define the block. 3. The starting address must be divisible by the number of addresses in the block. Datagram consists of two parts: 1. a header 2. data (payload) internet Protocol (IPv4): 1. Host-to-host network layer delivery protocol for the internet. 2. It is unreliable and connectionless protocol. 3. If reliability is of concern, the IP has to be tied to a connection-oriented protocol It is unreliable and connectionless protocol because: 1. No error control. 2. No flow control. 3. It has error detection (discard)
routing is the process of discovering network paths: 1. model the network as a graph of nodes and links 2. decide what to optimize fairness vs efficiency 3. update routes for changes in topology failures Routing Algorithms : 1. optimality principle 2. shortest path algorithm 3. flooding 4. distance vector routing Network Performance Measures 1. Quantity of Service (Throughput) 2. Quality of Service (Average packet delay) distance Vector Routing (an adaptive routing algorithm) algorithm: 1. Each node knows distance of links to its neighbors 2. Each node advertises vector of lowest known distances to all neighbors 3. Each node uses received vectors to update its own 4. Repeat periodically Information provided from neighbors: 1. Outgoing line used for destination 2. Estimate of time or distance Chapter6: The transport layer is responsible for: 1. Service point or Port addressing 2. Segmentation and reassembly 3. Connection Control 4. Flow control 5. Error control Type of data deliveries: 1. Data Link Layer: Node to Node delivery 2. Network Layer: Host to host delivery 3. Transport Layer: Process to process delivery For communication, we must define: 1. The local host: Defined using IP address 2. Local process: Defined using identifiers called port numbers 3. Remote host:: Defined using IP address 4. Remote Process: Defined using identifiers called port numbers 5. In the TCP/IP protocol suite, the port numbers are integers between 0 and 65,535 (16 bits).
Port Addressing: 1. Ephemeral port number 2. Server port number Ephemeral port number: 1. Defined by the client program. 2. Ephemeral (Short Lived) is used to describe these port numbers because the life of a client is normally short. Server port number: 1. The server process must also define itself with a port number. 2. Port number cannot be chosen randomly. A transport-layer protocol in the TCP suite at both ends needs the following to establish connection: 1. IP address 2. port number Multiplexing (many to one): 1. When ever an entity accepts items from more than one source. 2. The transport layer at the source performs multiplexing De-multiplexing (one to many): 1. When ever an entity delivers items to more than one source. 2. The transport layer at the destination performs de-multiplexing. Two cases of flow control at the transport layer: 1. From the sending transport layer to the sending application layer and 2. From the receiving transport layer to the sending transport layer Error control at the transport layer is responsible for: 1. Detecting and discarding corrupted packets. 2. Keeping track of lost and discarded packets and resending them. 3. Recognizing duplicate packets and discarding them. 4. Buffering out-of-order packets until the missing packets arrive. transport protocols in the Internet TCP/IP Protocol Suite: 1. UDP (User data gram protocol) 2. TCP (Transmission Control protocol) 3. SCTP
User Datagram Protocol (UDP) 1. Connectionless, unreliable transport protocol. 2. It does not add anything to the services of IP except for providing process-to-process communication instead of host-to-host communication. 3. UDP is a very simple protocol using a minimum of overhead. UDP packets user datagrams : 1. Fixed-size header of 8 bytes made of four fields, each of 2 bytes (16 bits). 2. The first two fields define the source and destination port numbers. 3. The third field defines the total length of the user datagram, header plus data 4. The 16 bits can define a total length of 0 to 65,535 bytes. 5. The total length needs to be less because a UDP user datagram is stored in an IP datagram with the total length of65,535bytes. 6. The last field can carry the optional checksum UDP Services: 1. Process-to-Process Communication 2. Connectionless Services different 3. no Flow Control 4. no Error Control 5. Checksum 6. no Congestion Control 7. Encapsulation and Decapsulation 8. Multiplexing and Demultiplexing TCP Services: 1. Process-to-ProcessCommunication 2. Stream Delivery Service 3. Full-Duplex Communication 4. Multiplexing and Demultiplexing 5. Connection-Oriented Service 6. Reliable Service UDP checksum calculation includes three sections: 1. A pseudo-header 2. The UDP header 3. the data coming from the application layer. TCP is a connection-oriented protocol. When a process at site A wants to send to and receive data from another process at site B, the following three phases occur: 1. The two TCP s establish alogical connection between them. 2. Data are exchanged in both directions. 3. The connection is terminated. 4. This is a logical connection, not a physical connection.
TCP s general policy for handling congestion is based on three algorithms: 1. slow start 2. congestion avoidance 3. fast recovery.