What Is a Queuing Delay?

Delay is the time required for data to travel from one end of the network to the other. Queuing delay refers to the number of routers that packets need to pass through when they are transmitted through the network. However, after entering the router, the packets are queued in the input queue for processing. After the router determines the forwarding interface, it will also wait in the output queue for forwarding.

The queuing delay refers to the time that a packet waits in the queue to be sent to the outbound link; the queuing delay of a particular packet depends on the number of packets waiting to be forwarded out through the same outlink. Packet queuing delay depends on the response

Sending delay (transmission delay): It is the time required by the host or router to send a data frame, that is, the time from the first bit of the data frame to the completion of the last bit of the frame. Delay = data frame length (b) / channel bandwidth (b / s).

Propagation delay: It is the time it takes for electromagnetic waves to travel a certain distance in the channel. Propagation delay = channel length (m) / electromagnetic wave propagation rate on the channel (m / s).

The transmission delay (transmission delay) occurs in the internal transmitter of the machine, and the propagation delay occurs on the transmission channel medium outside the machine.

Processing delay: When receiving a packet, the host or router takes a certain amount of time to process it, such as analyzing the header of the packet, extracting the data part from the packet, making an error, or finding an appropriate route.

Packaging latency is a latency unique to real-time streaming applications. Real-time streaming applications are applications that transmit time-based information (such as video, audio, and animation) in real time. The real-time information flow is time-based and is generated regularly in chronological order. It is necessary to wait for a certain amount of information flow to meet the protocol data unit (PDU) payload before it is packaged into a PDU. This waiting time is called the packet delay. For low-speed encoders, the delay is relatively large.

Network latency refers to the period of time from when a user sends a request to the remote system to respond to the request and return it to the user. For the Internet based on the TCP / IP protocol, each request must be processed as follows: routing processing, ADU (User Data Unit) transmission on the network, and server processing of the request. These processes will cause delays.

Routing delay, which includes domain name request delay, TCP connection establishment delay, TCP connection release delay, and IP routing delay on each gateway.

Packet switching is a store-and-forward switching method. It divides the user's message into packets of a certain length and uses the packet as a store-and-forward. Therefore, it has a higher utilization rate than circuit switching and a smaller delay than the message exchange , And has the ability to communicate in real time. Packet switching uses the principle of statistical time division multiplexing to multiplex a data link into multiple logical channels, and finally constitutes an information transmission path between the calling and called users, which is called a virtual circuit (VC) to implement data grouping. Send. Packet switching is an advanced communication method developed to adapt to computer communication. It is based on the CCITTX.25 recommendation and can meet different speeds, different models of terminals and terminals, terminals and computers, computers and computers, and LAN communications. To achieve database resource sharing. The packet-switched network is the basic network for data communication. With its network platform, various value-added services can be developed, such as: e-mail, electronic data exchange, video teletext, fax storage and forwarding, and database retrieval. The outstanding advantage of a packet-switched network is that multiple virtual circuits can be opened on one circuit at the same time and used by multiple users at the same time. The network has dynamic routing functions and advanced error correction functions, and the network performance is the best. China Public Packet Switched Data Network is a national packet switched data network operated by China Telecom. The network has directly covered all cities and counties. Through the telephone network, it can cover all cities accessible by the telephone network. Users can use the dedicated line nearby Or dial into the network by telephone and use packet switching services.