IBPS SO IT Officer Computer Networking Notes
IBPS SO IT Officer Computer Networking Notes
Network-
When two or more computer systems connect with each other to share resources or data/information then they form a network.
Networking Models
There are two networking models-
OSI (Open System Interconnection) Model- It is developed by ISO (International Organization of Standardization). This is conceptual model which divides the communication process from sender to receiver into seven layers.
OSI Model
| Layers No. | Layer Name and name of data called at different level | Protocols | Device Used | Tasks done by layer |
| Layer 7 | Application Layer
(Data) |
SMTP, HTTP, FTP, DHCP,SNMP, Telnet | – | Resource sharing, network management, remote file access etc. |
| Layer 6 | Presentation Layer
(Data) |
TBI,MPEG,S/MIME,TLS | – | Data Conversion, Data Encryption, character code translation, compresses data |
| Layer 5 | Session Layer
(Data) |
NCP,PAP,SCP | – | This layer allows session establishment, maintenance and termination. Performing security and name recognition and logging |
| Layer 4 | Transport Layer
(Segment and Data-gram) |
UDP(Data-gram),TCP(Segments) | – | This layer ensure that data is send error free, sequentially with no losses and Duplication |
| Layer 3 | Network Layer
(Packets) |
ICMP,IGMP,RIP, IPv4, IPv6 | Router | Takes Routing Decisions, Logical Physical Address Mapping |
| Layer 2 | Data Link Layer
(Frames) MAC (Media Access Control )layer LLC (Logical Link Control) Layer |
ARP,RARP | Switches, Bridges, NIC | Provide error free transmission, Link Establishment and Termination,
Transmits and Receives Frames Sequentially |
| Layer 1 | Physical Layer
(Bits) |
Modem, Repeater, Hub, NIC | Transmit and Receive un ordered raw stream over a physical medium |
TCP/IP V/S OSI Model
TCP/IP (Transmission control protocol and internet protocol) Model- This is the networking communication model that divides whole process of communication into four layer only. This protocol suite is result of the research and development conducted by DARPA (Defense Advanced Research Project Agency).
TCP/IP have four layers.
Layer 4- application layer
It allow user to access network. Some protocols are used in this layer:
FTP (file transfer protocol)– it is responsible for reliable delivery of files on the network.
SMTP (simple mail transfer protocol)– It is responsible for uploading and downloading of web pages by browser. It is connection less protocol.
HTTP (hypertext transfer protocol)- It is used to send mails from client to server.
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Layer 3- Transport Layer
It contain raw data received from application layer into segments and perform error control and flow control. It is used by UDP/TCP.
UDP (user data-gram protocol) it is an unreliable, connection-less protocol. It is used for client-server type request in which prompt delivery is more important than accurate delivery.
Layer 2- Internet layer
Information obtained from transport layer is converted into data packets. IP is used for transmission here. Some protocols are also there such as IP,ARP,RARP,ICMP,IGMP. Etc.
IP (internet protocol)– Its is connection-less protocol and responsible for breaking data packets into small packets and takes different path to reach the destination.
ARP (address resolution protocol)-. It associates logical address with MAC address of the machine which is printed on NIC.(NETWORK INTERFACE CARD)
RARP ( reverse address resolution protocol) – It associates physical address with logical address. It is used when computer is used first time or disk-less computer booted first time.
ICMP (internet control message protocol) – used to send notification to the sender about problem related to data packets.
Layer 1 – Network interface layer
In this layer frames are breaking down into bits for transmission across the physical media. FDDI, Ethernet,token ring etc are defined for data transmission.
IBPS SO IT Officer Computer Networking Notes
Circuit switching
Circuit switching is done at physical layer. In this switching first a physical connection is made between the computers after that transmission is takes place. Data flow only by defined path. Data lost cannot be recovered here. Connection break only when transmission completed.
Packet switching
A complete message is break down into smaller chunks of packets contain information that are transmitted. Internet used packet switching technique. Packets are transmitted based on priority so packets are store and forward according to preferences.
Message switching
Whole message is transmitted. First check the next hop is free or not if hop is free then Message is store and forward to next hop. This process is continue until received by receiver. Some limitations are there:
- Store and forward technique is used.
- Need storage for entire message.
- Not suitable for media and real time applications.
Data communication channel
Deals with transmission of data from one device to another device through communication channel. Communication channel has source or transmitter at one side and destination or receiver at other side.
Communication channel is of 3 type:
Simplex : This is unidirectional. One of the device can transmit the data and other can only receive the data. Eg radio broadcasting.
Half duplex : This is bidirectional. Device can transmit and receive data only in one direction at one time. Eg. walkie-talkie
Full duplex : communication in both the direction at one time. Eg telephone.
Transmission Media
Material through which data communication takes place.
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Coaxial cable
Contains two parallel conductors. Copper is used as a central conductor which is a solid wire. It is covered by PVC. outer core is used against noise and inner core for signal.
Advantage
- High bandwidth
- High noise immunity.
- Data transmit without distortion.
- Data transmit at high rate.
Disadvantage
- Failure in one signal can fail the entire connection
- Not easy to install
- Expensive
Fiber optic cable
Use electric signal to transmit data . glass core is used in central. Glass core or signals are surrounded by glass cladding with lower index of refraction. Cladding is covered with plastic jacket to protect cladding.
Bandwidth of fiber cable is 2 gbps(giga byte per second)
Advantage
- High speed.
- Noise and distortion less.
- Used in both analog and digital signal.
Disadvantage
- Expensive
- Difficult to install
- Maintenance expensive.
Twisted Pair Cable
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