Computer Networks

Computer Network 

An interconnection of multiple devices, also known as hosts, that are connected using multiple paths for the purpose of sending/receiving data or media. 

Computer networks can also include multiple devices/mediums which help in the communication between two different devices:

• routers
• switches 
• hubs 
• bridges

these are known as Network devices.

TOPICS:

DATA COMMUNICATION COMPONENTS: 

1. Representation of data and its flow Networks
2. Various Connection Topology
3. Protocols and Standards
4. OSI model

• The OSI model 7 layers are:

1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data Link
7. Physical

    5. Transmission Media

• LAN: Wired LAN
• Wireless LANs
• Connecting LAN and Virtual LAN

    6. Techniques for Bandwidth utilization: 

• Multiplexing - Frequency division
• Time division and 
• Wave division

DATA LINK LAYER AND MEDIUM ACCESS SUB LAYER: 

1. Error Detection and Error Correction 
2. Block coding
3. Hamming Distance
4. CRC; 
5. Flow Control and Error control protocols - Stop and Wait
6. Goback - N ARQ
7. Selective Repeat ARQ
8. Sliding Window
9. Piggybacking
10. Random Access
11. Multiple access protocols - Pure ALOHA
12. Slotted ALOHA
13. CSMA/CD
14. CDMA/CA

Network Layer:

1. Switching
2. Logical addressing - IPV4, IPV6
3. Address mapping - ARP
4. RARP
5. BOOTP and DHCP - Delivery
6. Forwarding and Unicast Routing protocols

Transport Layer: 

1. Process to Process Communication
2. User Datagram Protocol(UDP)
3. Transmission Control Protocol (TCP)
4. SCTP Congestion Control; Quality of Service
5. QoS improving techniques: 

• Leaky Bucket 
• Token Bucket algorithm.

Application Layer: 

1. Domain Name Space (DNS)
2. DDNS, TELNET
3. EMAIL, File 
4. TransferProtocol (FTP)
5. WWW
6. HTTP
7. SNMP
8. Bluetooth
9. Firewalls
10. Basic concepts of Cryptography

Network Topology: 

Network Topology defines the structure of the network of how all the components are interconnected to each other.

• There are five types of topology:

1. Mesh
2. Star
3. Bus
4. Ring 
5. Hybrid

IP Address (Internet Protocol address): 

• IP Address is the network address of the system across the network. 
• To identify each device in the world-wide-web, the Internet  Assigned Numbers Authority (IANA) assigns an IPV4 (Version 4) address as a unique identifier to each device on the Internet. 
• The length of an IPv4 address is 32-bits, 
• hence, we have 232 IP addresses available. 
• The length of an IPv6 address is 128-bits.

Protocol: 

A protocol is the set of rules or algorithms which define the way how two entities can communicate across the network and there exists different protocol defined at each layer of the OSI model. Such protocols are:

• TCP
• IP
• UDP
• ARP
• DHCP
• FTP

OSI Model: 

OSI stands for Open Systems Interconnection. 

It is a reference model that specifies standards for communications protocols and the functionalities of each layer.

• The OSI model 7 layers are:

1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data Link
7. Physical

MAC Address (Media Access Control address): 

• The MAC Address is the unique identifier of each host and is associated with its NIC (Network Interface Card). 
• The length of the MAC address is : 12-nibble/ 6 bytes/ 48 bits

Port: 

A port can be referred to as a logical channel through which data can be sent/received to an application.

Application Layer Functions:

• This layer is helpful to interact with user.

• This provides services to user to use network.

• It provides user services like user login, naming to network devices network,

   formatting messages, e-mail, transfer of files etc.

• It is used for error handling and recovery of the transferred of the message.

• It provides services by using different Protocol

• FTP

• Telnet

• SMTP

• DNS

• HTTP

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