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Transmission Delay
In a network based on packet switching, transmission delay (or store-and-forward delay, also known as packetization delay or serialization delay) is the amount of time required to push all the packet's bits into the wire. In other words, this is the delay caused by the data-rate of the link. Transmission delay is a function of the packet's length and has nothing to do with the distance between the two nodes. This delay is proportional to the packet's length in bits. It is given by the following formula: :D_T = N/R seconds where: :D_T is the transmission delay in seconds; :N is the number of bits; :R is the rate of transmission (say, in bits per second). Most packet switched networks use store-and-forward transmission at the input of the link. A switch using store-and-forward transmission will receive (save) the entire packet to the buffer and check it for CRC errors or other problems before sending the first bit of the packet into the outbound link. Thus, store-and-forward pac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Network
A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or by wireless communication. The devices may be connected in a variety of network topologies. In order to communicate over the network, computers use agreed-on rules, called communication protocols, over whatever medium is used. The computer network can include personal computers, Server (computing), servers, networking hardware, or other specialized or general-purpose Host (network), hosts. They are identified by network addresses and may have hostnames. Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Switching
In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consist of a header (computing), header and a payload (computing), payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or Protocol stack, higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. During the early 1960s, American engineer Paul Baran developed a concept he called ''distributed adaptive message block switching'', with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Switched
In telecommunications, packet switching is a method of grouping data into short messages in fixed format, i.e. '' packets,'' that are transmitted over a digital network. Packets consist of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. During the early 1960s, American engineer Paul Baran developed a concept he called ''distributed adaptive message block switching'', with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted then-established principles of pre-allocation of network bandwidth, exemplified by the development of telecommun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclic Redundancy Check
A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data. Blocks of data entering these systems get a short ''check value'' attached, based on the remainder of a polynomial division of their contents. On retrieval, the calculation is repeated and, in the event the check values do not match, corrective action can be taken against data corruption. CRCs can be used for error correction (see bitfilters). CRCs are so called because the ''check'' (data verification) value is a ''redundancy'' (it expands the message without adding information) and the algorithm is based on ''cyclic'' codes. CRCs are popular because they are simple to implement in binary hardware, easy to analyze mathematically, and particularly good at detecting common errors caused by noise in transmission channels. Because the check value has a fixed length, the function that generates it is occasionally used as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
End-to-end Delay
End-to-end delay or one-way delay (OWD) refers to the time taken for a Packet (information technology), packet to be transmitted across a computer network, network from source to destination. It is a common term in IP network monitoring, and differs from round-trip time (RTT) in that only path in the one direction from source to destination is measured. Measurement The ping utility measures the RTT, that is, the time to go and come back to a host. Half the RTT is often used as an approximation of OWD but this assumes that the forward and back paths are the same in terms of congestion, number of hops, or quality of service (QoS). This is not always a good assumption. To avoid such problems, the OWD may be measured directly. Direct OWDs may be measured between two points ''A'' and ''B'' of an IP network through the use of synchronized clocks; ''A'' records a timestamp on the packet and sends it to ''B'', which notes the receiving time and calculates the OWD as their difference. The t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Processing Delay
In a network based on packet switching, processing delay is the time it takes routers to process the packet header. Processing delay is a key component in network delay. During processing of a packet, routers may check for bit-level errors in the packet that occurred during transmission as well as determining where the packet's next destination is. Processing delays in high-speed routers are typically on the order of microseconds or less. After this nodal processing, the router directs the packet to the queue where further delay can happen (queuing delay). In the past, the processing delay has been ignored as insignificant compared to the other forms of network delay. However, in some systems, the processing delay can be quite large especially where routers are performing complex encryption algorithms and examining or modifying packet content. Deep packet inspection done by some networks examine packet content for security, legal, or other reasons, which can cause very large del ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queuing Delay
In telecommunications and computer engineering, the queuing delay is the time a job waits in a queue until it can be executed. It is a key component of network delay. In a switched network, queuing delay is the time between the completion of signaling by the call originator and the arrival of a ringing signal at the call receiver. Queuing delay may be caused by delays at the originating switch, intermediate switches, or the call receiver servicing switch. In a data network, queuing delay is the sum of the delays between the request for service and the establishment of a circuit to the called data terminal equipment (DTE). In a packet-switched network, queuing delay is the sum of the delays encountered by a packet between the time of insertion into the network and the time of delivery to the address. Router processing This term is most often used in reference to routers. When packets arrive at a router, they have to be processed and transmitted. A router can only process one p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propagation Delay
Propagation delay is the time duration taken for a signal to reach its destination, for example in the electromagnetic field, a wire, speed of sound, gas, fluid or seismic wave, solid body. Physics * An electromagnetic wave travelling through a medium has a propagation delay determined by the speed of light in that particular medium, or ca. 1 nanosecond per in a vacuum. * An electric signal travelling through a wire has an propagation delay of ca. 1 nanosecond per . See also radio propagation, velocity factor, signal velocity and mechanical wave. Electronics Logic gates can have a gate delay ranging from picoseconds to more than 10 nanoseconds, depending on the technology being used. It is the time between the gate input becoming stable and the gate output becoming stable. Manufacturers often refer to the time from the input changing to 50% of its final input level, to the output reaching 50% of its final output level; this may depend on the direction of the level cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Delay
Network delay is a design and performance characteristic of a telecommunications network. It specifies the latency for a bit of data to travel across the network from one communication endpoint to another. It is typically measured in multiples or fractions of a second. Delay may differ slightly, depending on the location of the specific pair of communicating endpoints. Engineers usually report both the maximum and average delay, and they divide the delay into several parts: * Processing delay time it takes a router to process the packet header * Queuing delay time the packet spends in routing queues * Transmission delay time it takes to push the packet's bits onto the link * Propagation delay time for a signal to propagate through the media A certain minimum level of delay is experienced by signals due to the time it takes to transmit a packet serially through a link. This delay is extended by more variable levels of delay due to network congestion. IP network delays c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-trip Delay
In telecommunications, round-trip delay (RTD) or round-trip time (RTT) is the amount of time it takes for a signal to be sent ''plus'' the amount of time it takes for acknowledgement of that signal having been received. This time delay includes propagation times for the paths between the two communication endpoints. In the context of computer networks, the signal is typically a data packet. RTT is commonly used interchangeably with ping time, which can be determined with the ping command. However, ping time may differ from experienced RTT with other protocols since the payload and priority associated with ICMP messages used by ping may differ from that of other traffic. End-to-end delay is the length of time it takes for a signal to travel in one direction and is often approximated as half the RTT. Protocol design RTT is a measure of the amount of time taken for an entire message to be sent to a destination and for a reply to be sent back to the sender. The time to send the mes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
