Open Architecture Networking

The Internet uses an open architecture networking. Designers are free to design networks however they want. All these networks can communcicate over the internet.

Each network is connected to the Internet through a router gateway.

Within national boundaries, networks belonging to a large business or a unversity connect directly to the national backbone, whereas smaller organisations or individuals connect via an ISP, who are then connected to the backbone

Routers

Routers are special switches that recieve incoming packets of data along one link and send that as an outgoing packet to another link. Each packet contains the IP of the destination, which is used to find the destination and to choose the right outgoing link. Each network is connect to the Internet through a router gateway. A router gateway allows one network to be connected to another so that packets from one network can be translated into a form which is compatible to the next A gateway is only necessary when the communication channels on either side of it use different link layer protocols. If the channel uses the same link layer protocol, the machine is just a router.

Gateways

Gateways regulate traffic between two dissimilar networks, while routers regulate traffic between similar networks. A gateway is only necessary when the communcation channels on either side of it use differernt link layer protocols. If the channel uses the same link layer, a router is used.

Examples of networks

Label Expansion
WAN Wide Area Network
MAN Metropolitan Area Network
CAN Campus Area Network
LAN Local Area Network
WLAN Wireless Local Area Network
PAN Personal Area Network

Topologies

Thing Explaination
Bus All the computers are connected to the same wire, called the backbone
Ring All the computers are linked in a ring, and a token is passed around
Star All the computers are connected to a switch
Mesh All the computers are connected to each other
Wireless Uses electromagnetic radiation to transmit via the power of a WLAN

Intranet

The Intranet is a term often used to refer to a private connection of LANs and WANs that belongs to an organisation, and is only accessed via the members of the organisation.

Internet

Nobody owns the internet. However, people still does regulate it.

The internet society was established in 1992 to oversee and manage network protocols and systems.

Network Protocol

A network protocol is a set of rules that a program folows. This allows for a standardised format of communication.

These rules define:

  • How to establish and terminate a communication
  • The format of the data being transferred
  • Error checking and correction
  • Compression

The most common protocol is the TCP/IP protocol.

TCP/IP

The protocols that make TCP/IP define how data is transferred over a network. Programs use TCP/IP to make up network protocols.

End node verification

TCP/IP is decentralised.

Protocols that use TCP/IP

Thingy Name Port What
SSH Secure Shell 22 Remote control command prompt
Telnet Terminal Emulation Link Network 23 Remote control command prompt
POP3 Post Office Protocol Version 3 110, (465) Emails!
SMTP Simple Mail Transfer Protocol 143, (993) Emails!
HTTP Hypertext Transfer Protocol 80 A protocol which transfers files, such as HTML to be viewed in a web browser.
HTTP2 Hypertext Transfer Protocol Version 2 80 A second version which allows for more simultaneous requests to occur.
HTTPS Hypertext Transfer Protocol (Secure!) 443 The same as HTTP, but wrapped up in a cozy shell of SSL
FTP File Transfer Protocol 21 Move files across the internet!
SMB Server Message Block Move files across the intranet! Also contains other Mircosoft things.
WebDAV Web Distributed Authoring and Versioning 80, 443 Move files across the internet! An extension to HTTP
SFTP Secure File Transfer Protocol 22 Move files across the internet! Uses SSH to securely route files.
CSMA/CD Carrier-sense Multiple Access (with) Collision Detection If there is a collision, send a packet after a random time, up to 60 seconds before discarding a packet.
CSMA/CA Carrier-sense Multiple Access (with) Collision Avoidance Send a packet after a time period

MAC

A MAC address, or a (Machine Access Code) allows for the TCP/IP to transfer data to the correct computer. This MAC is hard-coded into the physical network interface card.

Name Servers

Name servers store the mapping information between IP addresses and Domain Names. This data is stored within a DNS server.

Error Checking

All data transmissions are checked for corruption, and have ACKnowledgements.

Ports

Ports are logical "pipelines" which allow for multiple applications to communicate simultaneously.