Application - Contructs message with address
Transport - Splits message into packets
Network - Handles routing through the Internet
Link - Handles actual transmission of packets
These are high level protocols built on the foundation of the TCP/IP protocol suite.
|20||File Transfer Protocol - FTP|
|22||Secure Shell - SSH|
|25||Simple Mail Transfer Protocol - SMTP|
|69||Trivial File Transfer Protocol - TFTP|
|80||Hypertext Transfer Protocol - HTTP|
|110||Post Office Protocol - POP3|
|115||Simple File Transfer Protocol - SFTP (not to be confused with SSH File Transfer Protocol, which operates on a different port)|
|119||Network News Transfer Protocol - NNTP|
|123||Network Time Protocol - NTP|
|143||Internet Message Access Protocol - IMAP|
|443||Secure Hypertext Transfer Protocol - HTTPS|
Internet backbone - A set of high speed networks that carry Internet traffic. These are provided by large telecomms companies
Internet Service Provider - A company that provides other companies or individuals with access to the Internet
To improve the efficiency of transferring information over a shared communication line, messages are divided into fixed-sized, numbered packets. Network devices called routers are used to direct packets between networks.
The message is split into packets. Packets are sent over the Internet by the most expedient route. Packets are reordered then reassembled into the original message.
Advantages of Packet Switching
- No wasted bandwidth - Links are not reserved during idle periods
- Serivce - more connections of lesser quality, and no blocking of users
- Adaptation - If there is a failure point, the network can recover and work around it
Disadvantages of Packet Switching
- No guaranteed bandwidth - Harder to build applications requiring QoS
- Per packet overhead - packet headers etc
- Complex end-to-end control - Packets can be lost, corrupted during transit, or delivered in the incorrect order
- Delay and congestion - due to no congestion control, arbitrary delays and packet drops can occur
Proprietary system - A system that uses technologies kept private by a particular commercial vendor
Interoperability - The ability for software and hardware on multiple machines and from multiple commercial vendors to communicate
Open systems - Systems based on a common model of network architecture and a suite of protocols used in its implementation
The ISO established the Open Systems Interconnection Reference Model - OSI. Each layer deals with a particular aspect of network communication.
They are layered such that each one relies on the protocols that underlie it. Somtimes this results in it being referred to as a protocol stack.
TCP stands for Transmission Control Protocol
TCP software breaks messages into packets, hands them off to the IP software for delivery, and then orders and reassembles the packets at their destination.
IP stands for Internet Protocol
IP software deals with the routing of packets through the Internet to their final destination
UDP stands for User Datagram Protocol
It is a TCP alternative. The main difference being that TCP is highly reliable at the cost of descreased performance, while UDP is less reliable, but generally faster.
A method by which multiple signals are data streams are combined into one signal over a shared cable. The goal is to share an expensive resource.
Time Division Multiplexing
Frequency Division Multiplexing
A smarter kind of multiplexing that can dedicate larger or smaller channels of bandwidth depending on the application. A large bandwidth application such as streaming TV, can be dedicated more bandwidth than an email application.