Network

Components in Network

• End devices (hosts): phone, tv, printer, ...
• Media: line, cables, ...
• Protocol

Data Network

Categories by Geo

• LAN: Local Area Network
• WAN: Wide Area Network
• MAN: Metropolitan Area Network
• GAN: Global Area Network (continents connection)
• SAN: Storage Area Network (peformance + Availability + Scalability)
• VPN: Virtual Private Network

Param	LAN	WAN
Speed	high, upto 1-10 Gbps	much lower, generally 100 mbps
Congestion	Less congested	More congested
Components	using the layer 1/2 devices like hubs, swiches, brigdes & layer 3 devices like Core/Layer 3 switch	using the layers 3 devices Routers & Multi-layer Switches
Ownership & management	owned, operated, managed & monitored by a customer	by multiple Service providers
Security	More secured	Less secured
Technologies	Ethernet & Token Rings	MPLS, ATM, Frame replay & ISDN, ...
Cost	Less expensive	More expensive
Physical layer connectivity	Generally Copper & Fiber medium. Multimode Fider is preferred.	Fiber medium. Single mode Fiber is preferred

WAN vs LAN vs PAN vs MAN

Categories by switching

VPN (Virtual Private Network)

Connect objects

• Headquarter
• Branch
• Home user
• Mobile user (laptop, mobile)

https://www.slideshare.net/OECLIBOdishaElectron/virtual-private-networks-vpn-ppt

Types :

• Network to network (Site to Site)
  • Intranet: network same company
  • Extranet: network between multi companies
• User to Network (Remote-Access VPN) (POP)

Media

LAN Media

• đồng trục
• xoắn đôi
• cáp quang
• vô tuyến

WAN Media

• modem (dial-up)
• public data network service (VPN, Frame-relay)
• đường thuê bao dùng riêng (Leasedline based on bandwidth)

Models

Communication Process

Source Address ----- Protocol on Media ----- Destination Address

• Addresses: who are the source & destination of a communication process
• Media: where is the communication take place
• Protocols: set of rules how to make communication on a network

OSI vs TCP/IP

1. Physical: Binary transmission
   • wires, connectos, voltages, data rates
2. Data Link: Access to media
   • provides reliable transfer of data across media
   • physical addressing, logical network topology, error notification, flow control
3. Network: address & best path
   • provides connectivity & path selection between 2 end systems
   • domain of routing
4. Transport: e2e connections
   • concerned with transportation issues between hosts
   • data transport reliability
   • establish, maintain, terminate virtual circuits
   • fault detection & recovery infor flow control
5. Session: Dialog control - interhost communication
   • establish, maintain, terminate sessions between applications
   • half duplex / full duplex
6. Presentation: Data representation
   • ensure data is readable by receiving system
   • format of data
   • data structure
   • negotiates data transfer syntax for app layer
7. Application: network processes to apps

Encapsulation Process

https://afteracademy.com/blog/what-is-data-encapsulation-and-de-encapsulation-in-networking/

TCP vs UDP

• Checksum
• Acknowledgement
• Re-transmission (timeout & ACK dup)

Layer 1 vs Layer 2

Layer 1	Layer 2
cannot organize streams of bit	uses framming to organize or group the bits
cannot identify computer	uses an addressing process to identify computer
cannot communicate with the upper-level layers	uses LLC to communicate with the upper-level laye
cannot decide which computer will transmit binary data	uses MAC to decide which computer will transmit

TCP and UDP Application Ports

In networking, different ports are used for various purposes. Generally, these port ranges can be divided into three categories. Below, you can find these port ranges:

• Well-Known Ports ( 1 to 1024 ) TCP Ports
  • FTP Data (Port 20)
  • FTP Control (Port 21)
  • SSH (Port 22)
  • Telnet (Port 23)
  • SMTP (Port 25)
  • TACACS (Port 49)
  • HTTP (Port 80)
  • POP3 (Port 110)
  • SFTP (Port 115)
  • HTTPS (Port 443) UDP Ports
  • DHCP & BOOTP Server (Port 67)
  • BOOTP User (Port 68)
  • TFTP (Port 69)
  • NTP (Port 123)
  • SNMP (Port 161)
  • SNMP Trap (Port 162)
  • Syslog (Port 512)
  • ISAKMP (Port 500)
• Registered Ports ( 1025 to 49151 )
• Private Ports ( 49152 to 65535 )

Protocols

Common protocols

Common servers

Vokas

• Round-trip time (RTT)
• Network Interface Card (NIC)
• 1 B (Byte) = 8 bit (b)
• 1024 B = 1 KB
• Bandwith (bps - bit per second)
• Through put <= Bandwidth ( P (throughput) = S (size of file) / T (time to download) )
• LLC - Logical Link Control
• MAC - Media Access Control

Tools

• Decimal to Binary converter (opens new window)
• Visual Subnet Calculator (opens new window)
• CIDR (opens new window)

Refs

https://viblo.asia/p/so-sanh-chi-tiet-tcp-va-udp-tai-sao-udp-lai-nhanh-hon-tcp-zOQJw05xLMP