NETWORKING SIMPLE AND SHORTS NOTES #JUST READ IT

* Networking

- basics
  - units
    - B: bytes
    - b: bits
  - IEEE standard: 802
    - 802.3: ethernet
    - 802.3u: fast ethernet
    - 802.11: WiFi
    - 802.15: BlueTooth
  - definition
    - collection/group of devices (mobiles/machines/kitchen application)
    - to exchange/share the information
  - topology
    - physical arrangement of machines
    - types
      - bus
      - ring
      - connected ring
      - star
      - mesh
  - types
    - wired
      - medium: wire/cable
      - cables
        - co-axial
        - category cable (cat cable) (Twisted pairs)
          - types
            - UTP: Unshielded Twisted Pairs
            - STP: Shielded Twisted Pairs
          - versions
            - cat 3: 10Mbps
            - cat 4: 15Mbps
            - cat 5: 100Mbps
            - cat 5e: 125Mbps
            - cat 6: 1000Mbps ~ 1Gbps
        - optical fiber
      - types
        - LAN: Local Area Network
        - MAN: Metropolitan Area Network
        - WAN: Wide Area Network
        - CAN: Campus Area Network

    - wireless
      - medium: air (EM Waves)
      - types
        - PAN: Personal Area Network (BlueTooth/ZigBee)
        - WLAN: Wireless LAN
        - GSM: Global System For Mobile Communication
        - CDMA: Code Division Multiple Access

- addressing scheme
  - MAC address
    - also called as physical address
    - used to identify a NIC uniquely in LAN
    - hardwired into NIC
    - format: MM:MM:MM:NN:NN:NN
    - size: 6 bytes ~ 48 bits
    - first 3 bytes are used to identify the manufacture
    - last 3 bytes are used to identity the NIC
    - to get the MAC address
      - windows: ipconfig /all
      - linux/Mac: ifconfig
  - IP address
    - also called as logical address
    - used to identify the machine uniquely
    - format: N.N.N.N
      - decimal: 4.5.6.7
      - binary: 00000100.00000101.00000110.00000111
    - size: 4 bytes ~ 32 bits
    - types
      - private: used within a LAN
      - public: used in internet
    - subnet
      - sub-network (logical network within a network)
      - can be done by borrowing a bit from host part
    - class-full
      - class A
        - 0.0.0.0 - 127.255.255.255
        - private: 10.x.x.x
        - format: N.H.H.H
        - networks: 2^8
        - hosts: 2^24
        - subnet mask: 255.0.0.0
        - can NOT use:
          - 127.x.x.x
            - reserved for loopback address
            - e.g. 127.0.0.1 (loopback address for localhost / same machine)

      - class B
        - 128.0.0.0 - 191.255.255.255
        - private: 172.16.x.x - 172.32.x.x
        - format: N.N.H.H
        - networks: 2^16
        - hosts: 2^16
        - subnet mask: 255.255.0.0

      - class C
        - 192.0.0.0 - 223.255.255.255
        - private: 192.168.x.x
        - format: N.N.N.H
        - networks: 2^24
        - hosts: 2^8
        - subnet mask: 255.255.255.0

      - class D
        - 224.0.0.0 - 239.255.255.255
        - reserved for multicast address

      - class E
        - 240.0.0.0 - 255.255.255.255
        - reserved for research tasks


- standards
  - application layer
    - dns (53)
      - domain name service
      - used to get the ip address from domain name
    - http (80): hyper text transfer protocol
    - https (443): secure hyper text transfer protocol
    - ftp (20/21): file transfer protocol
    - sftp: secure file transfer protocol
    - ftps: file transfer protocol using SSH
    - ssh (22): secure shell
    - smtp: simple mail transfer protocol
    - pop3: post office protocol
    - arp: address resolution protocol -> used to find physical address from logical address
 - presentation layer
   - image: png/jpg/jpeg/bmp/gif
   - audio: wav/mp3
   - video: mp4/flv/div/mkv/avi
   - text: json/xml/plain
   - archived: zip/tar/gzip
 - session
   - sip: session initiation protocol
 - transport
   - tcp:
     - transmission control protocol
     - connection oriented protocol
     - flow control, error checking
     - slower than UDP
     - e.g. online banking
   - udp:
     - user datagram protocol
     - connection less protocol
     - no flow control, no error checking
     - faster than TCP
     - e.g. video streaming, online multiple games, dns
 -


* hub vs switch vs router
  - hub
    - works in physical layer
    - slower network
    - used to create a LAN
    - always sends the frame as broadcast
  - switch
    - works in data link layer
    - can identify the MAC address in the frame
    - used to create a LAN
    - most of the times it will be a unicast
      Few times it will be multicast
      One time it will be broadcast
  - router
    - works in network layer
    - used to create a WAN

* casting
  - unicast: sending to only one machine at a time
  - broadcast: sending to all the machines at a time
  - multicast: sending to multiple machines at a time


* ISO OSI model
  - Application
  - Presentation
  - Session
  - Transport
  - Network
  - Data Link
  - Physical






00000000.00000000.00000000.00000000
11111111.11111111.11111111.11111111


10.75.20.20 -> 00001010.01001011.00010100.00010100
255.0.0.0 -> 11111111.00000000.00000000.00000000
-------------------------------------------------------
10.0.0.0        -> 00001010.00000000.00000000.00000000

192.168.1.40
255.255.255.0
--------------
192.168.1.0

192.168.1.0 - 192.168.1.255

192.168.5.40
255.255.255.0
--------------
192.168.5.0

192.168.5.0 - 192.168.5.255




- class C and 95 hosts
- default subnet
  - 255.255.255.0
  - 11111111.11111111.11111111.00000000
- subnet mask
  - 11111111.11111111.11111111.10000000
  - 255.255.255.128
- networks: 2^24
- hosts: 2^8 = 256

-- network-----------------  --subnet-- -- host --

[11111111.11111111.11111111]. [00000000] -> 2^8 -> 256
[11111111.11111111.11111111]. [1] [0000000] -> 2^7 -> 128
[11111111.11111111.11111111]. [11] [000000] -> 2^6 -> 64
[11111111.11111111.11111111]. [111] [00000] -> 2^5 -> 32
[11111111.11111111.11111111]. [1111] [0000] -> 2^4 -> 16
[11111111.11111111.11111111]. [11111] [000] -> 2^3 -> 8
[11111111.11111111.11111111]. [111111] [00] -> 2^2 -> 4
[11111111.11111111.11111111]. [1111111] [0] -> 2^1 -> 2
[11111111.11111111.11111111]. [11111111] [] -> 2^0 -> 1


00000000 => 0
10000000 => 128
11000000 => 192
11100000 => 224
11110000 => 240
11111000 => 248
11111100 => 252
11111110 => 254
11111111 => 255






172.40.45.78
- 255.255.0.0
- 255.255.128.0
- 255.255.192.0
- 255.255.224.0
- 255.255.240.0
.
.
- 255.255.255.0


[11111111.11111111]. [00000000.00000000] -> 2^16
[11111111.11111111]. [1] [0000000.00000000] -> 2^15
[11111111.11111111]. [11] [000000.00000000] -> 2^14
.
.
[11111111.11111111]. [11111111] [.00000000] -> 2^8

sub net -> 2^n
hosts ->2^n-2

Spread spectrum

it means in network each signal has allocated a bandwidth example for Radio frequency it is in MHz
that is 89.* to 108.* for 4G network it is GHz so that each is transmitted deliberately with in bandwidth what it is allocated























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