Components of the Internet: communication subnets and resource subnets. Host is for the user information processing; Routers are used to forward packets, that is, to perform packet switching.
Computer networks are divided into: wide area network, metropolitan area network, local area network, personal area network.
Delay classification: transmission delay, propagation delay, processing delay, queuing delay.
Transparency: something that actually exists but looks as if it doesn’t exist.
Entity: Any hardware or software process that can send or receive information.
Communication Means of exchanging information between two parties: one-way communication, two-way alternating communication, two-way simultaneous communication.
Bandpass modulation: AM, FM, phase modulation.
Nye’s rule: in any channel, there is a limit to the rate at which symbols can be transmitted. If the rate exceeds this limit, serious cross-talk will occur, making the recognition of symbols by the receiver impossible.
Error-free reception: Any frame received by the data link layer at the receiving end can be considered with a probability close to 1 that no error occurred during transmission.