What are the automatic repeat request protocol?
The automatic repeat request (ARQ) protocol mainly included the stop-and-wait ARQ protocol and the continuous ARQ protocol. The continuous ARQ protocol also included the N-frame backward ARQ protocol and the selective repeat ARQ protocol. The work flow of the stop-and-wait ARQ protocol was as follows: the transmitting station must wait for an acknowledgment signal after sending out a frame, and then continue to send the next frame after receiving an acknowledgment signal, and then resend the frame after receiving a negative acknowledgment signal, and must resend the frame even if no acknowledgment signal is received within a certain time interval. The continuous ARQ protocol meant that the sender maintained a sending window of a certain size, and all the packets within the sending window could be sent out continuously without waiting for the other party's confirmation. Every time the sender received a confirmation, the sending window would slide forward by one packet. In the ARQ protocol that sent back N frames, after the sender sent a frame, it did not have to stop and wait for the other party's response. It could send several frames in a row. If it received a positive response from the receiver during the sending process, it could continue to send. If it received a negative response to a previous frame, all subsequent frames starting from that frame would be retransmitted. The selective repeat ARQ protocol can be used as a protocol for the transmission and acknowledgment of a message unit. When used as a protocol to transmit a message unit, the sending process continuously sends a number of frames according to a window of a specified size. Even if the frame is lost during the process, it will continue to send. The receiving process continued to receive and acknowledge frames even after the error. "Choose" was equally exciting. Everyone was welcome to read it!
How do I write the automatic repeat request protocol?
The automatic repeat request (ARQ) protocol was a technique used for error control in data communication. When the receiver detected an error, it automatically requested the sender to resend the data. The following are the basic steps to build an ARQ protocol: ** 1. Confirm ARQ Type ** 1. ** Stop and Wait ARQ protocol ** - Sending party: - Encapsulated the network layer data into a data frame. - The data frame was sent to the data link layer's transmission buffer and sent out. - Waiting for the receiver's reply signal. If an acknowledgment (ACK) is received, the next frame will be sent, and if a negative acknowledgment (NAK) is received or no acknowledgment is received within a certain time interval, the frame will be retransmitted. - Receiving party: - Waiting to receive the data frame. - After receiving the data frame, it was placed into the receive buffer of the data link layer. - If the data frame was correct, the data frame would be unpacked, and the grouped data would be handed over to the network layer, and an acknowledgment frame would be sent back to the sender. If the data frame was wrong, no processing would be done.(Under this protocol, the receiver would not feed back the information related to the wrong frame, and the sender would rely on time-out retransmissions.) 2. ** Continuous ARQ protocol ** - Sending party: - Maintaining a certain size of the sending window, all packets within the sending window can be sent out continuously without waiting for the other party's confirmation. - Every time he received a confirmation, he would slide the send window forward by one packet. - Receiving party: - They could only receive data frames in sequence. 3. ** ARQ protocol with N frames backoff ** - Sending party: - After sending a frame, there was no need to stop and wait for the other party's reply. Several frames could be sent consecutively. - If a positive response is received from the receiver during the transmission process, the transmission can continue; if a negative frame is received for a previous frame, all subsequent frames starting from the frame will be retransmitted. - The sent frames needed to be differentiated by different numbers, and there had to be a large buffer to hold the frames that could be retransmitted. 4. ** Repeat ARQ protocol ** - Sending party: - It continuously sends a number of frames according to a window of a specified size. Even if a frame is lost during the transmission, it will continue to be sent. - Receiving party: - Continue receiving and acknowledging frames after errors. ** 2. define the data frame structure ** 1. It contains an error detection code for detecting errors, such as a Cyclic Redundance Check (Cyclic Redundance Check) code. 2. There is a serial number of the frame (it is very important in the continuous ARQ protocol, the ARQ protocol with a fallback of N frames, and the ARQ protocol with a selective repeat to distinguish between different frames). 3. It contains the actual data to be transmitted. ** 3. Dealing with error detection and feedback ** 1. sending end - Before sending the data frame, the error detection code is first added to the data frame. - It waits for feedback from the receiver according to the selected ARQ type (ACK or NAK), and decides whether to resend the data frame according to the feedback. 2. receiving end - The received data frame was deciphered to determine if there was an error. - If there is no error, send an acknowledgment to the sender; if there is an error, send a NAK according to the type of ARQ protocol (for example, in the stop-and-wait ARQ protocol, the sender can also send an acknowledgment without sending an acknowledgment, allowing the sender to resend after a time limit) or continue to receive subsequent frames and record the number of the error frame in the selective re-transmission ARQ protocol so as to request for re-transmission. ** 4. Time-out mechanism (mainly for stop-and-wait ARQ protocol and continuous ARQ protocol)** 1. The sender set up a timer that started counting down from the time the data frame was sent. 2. If the receiver does not receive an ACK or NAK before the timer times out, the data frame will be retransmitted. ** 5. Code implementation example (Take the stop-and-wait ARQ protocol as an example, pseudocode)** ```python #sender def sender(data): for packet in data: frame = create_frame(packet) #Create a data frame that contains data and error detection codes send(frame) start_timer() while True: if received_ack(): stop_timer() break elif timer_timeout(): send(frame) start_timer() #Receiving party def receiver(): while True: frame = receive() if check_frame(frame): #Check if the frame is correct send_ack() process_packet(frame) #process the data in the data frame else: pass #Under the stop-and-wait protocol, the sender does not send a NAK, and the sender relies on the time-out to resend. ``` This is just a simple example. The actual ARQ protocol implementation may be more complicated due to the specific application scenario, network environment, and performance requirements. "Choose" was equally exciting. Everyone was welcome to read it!
Backward n frame protocol and selective repeat protocol
Go-back- N (GGN): - In the stop-and-wait protocol, the sender can only send one frame at a time, and the channel utilization rate is low. However, the backward N-frame protocol uses a sliding window method, and the sender maintains a set of sending windows, and can send multiple data frames at a time. The receiver uses the method of cumulative confirmation, and the sender moves the sending window forward after receiving the confirmation. When there was a problem (such as frame loss or long delay), the sender used the method of retreating N frames to re-transmit. The timer here was used to recover data frames or confirm the loss of frames, similar to the timer in the pause protocol. Choosing the Repeat protocol: - Different from the N-frame backward protocol, when the receiver receives an out-of-order frame, it will not discard all subsequent frames like the N-frame backward protocol. Instead, it will buffer the correctly received out-of-order frame. When the sender found that a frame was lost, it only retransmitted the lost frame, instead of retransmitting the subsequent N frames from the lost frame like the backward N frames protocol. This could avoid unnecessary data retransmissions and improve transmission efficiency, especially in a poor network environment with a high packet loss rate. Both of these two types of protocol were designed to deal with the loss of frames and the disorder of order during data transmission to improve the reliability and efficiency of data transmission. However, the specific ways in which they dealt with the problem were different. "Choose" was equally exciting. Everyone was welcome to read it!
Continuous arq protocol and sliding window protocol
In the continuous ARQ protocol, the sender maintained a sending window of a certain size, and the packets within the window could be sent continuously without waiting for the other party's acknowledgment. The sender would slide the sending window forward by one packet every time it received an acknowledgment. The receiver usually uses the method of accumulating acknowledgement, that is, after receiving several packets, it sends an acknowledgement to the last packet that arrives in order, indicating that all the packets up to this packet have been received correctly. However, this method has shortcomings. For example, when the middle packet is lost, the sender cannot know the situation of the subsequent packets, and may need to re-transmit more packets. The sliding window protocol involves a sending window and a receiving window. The transmit window is the range of sequence numbers of the frames that have been sent but have not been acknowledged, and the receive window is the range of sequence numbers of the frames that are expected to be received. When the default window size is 1, you can operate according to the specific sending process. The sliding window protocol could improve the channel utilization and was a reliable transmission mechanism for data communication. The continuous ARQ protocol can be seen as a specific application form of the sliding window protocol under certain conditions (such as the cumulative acknowledgment method). They are all protocol mechanisms that exist to achieve effective and reliable data transmission in the network. "Choose" was equally exciting. Everyone was welcome to read it!
The difference between AH protocol and EP protocol
ARP protocol
The Address Resolution Protocol was a network layer protocol. It was between the data link layer and the network layer. It played a vital role in network communication, just like the address translator in the network. Its main function was to convert the IP address of the network layer to the data link layer's IP address. This was because in network communication, although the IP address was used to identify the host at the network layer, it was forwarded through the IP address at the data link layer (such as the ether network). The host or the layer 3 network device would maintain an ARP-table to store the IP address and the MAC-address map. The ARP-table entries included dynamic and static ARP-table entries. The working process was as follows: When host A needed to communicate with host B, it first determined the forwarded IP address according to the route table, and then checked the local ARP-buffer. If there was no matching address, it would broadcast an ARP-request frame in the network. All hosts in the same broadcast domain will receive this request. For example, after receiving the request, host C will find that the destination address is not its own, and then it will buffer the address of host A into its own ARP-table, and then discard the packet. After receiving the request, host B will find that the destination address is its own, and then it will buffer the address of host A and give a response. Then it will package its own address in the response ARP-packet and send it to host A. After receiving the response, host A will update its own ARP-buffer. There were two ways to obtain the ARPs: static and dynamic. The static acquisition was equivalent to manually configuration of the address map in the ARP-table. If the physical address changed, it would need to be manually changed, which was more troublesome. The dynamic acquisition was to obtain and update the address map by the host through the protocol, which was relatively convenient. In addition, there was also a free ARP-type message that was used to detect whether there was an IP address conflict. It would send a broadcast message with the same source and destination IP. Under normal circumstances, it was not expected to receive a response. If a response was received, it meant that there was an address conflict. In the Windows system, there were related ARP-commands. For example, ARP-a could check the ARP-buffer table, and ARP-d could delete the ARP-buffer table. However, due to network communication requirements, the buffer table might be regenerated immediately. In November 1982, the Internet Engineering Task Force (IetF) published the Internet Packet Packet Interface Problem (ARPG) 826. It was an indispensable protocol for the Internet Packet Interface Version 4, which was the most widely used version of the Internet protocol.(The Internet Packet Interface Version 6 was still in the early stages of deployment.) The role of the ARP-protocol in the car's ether network was the same as that of the traditional ether network. "Choose" was equally exciting. Everyone was welcome to read it!
protocol translation
The price quoted for contractual translation was usually affected by many factors: 1. ** Language pair **: Common ones such as Chinese-English translation may cost 200 - 400 yuan per 1,000 words; translation between minor languages and Chinese may cost 300 - 500 yuan per 1,000 words. 2. ** The complexity of the agreement **: For general agreements, the terms are relatively common and simple, and the fee is relatively low, about 200 - 300 yuan/1,000 words; for agreements involving complicated legal terms, professional terms, and strict format requirements, the fee may be 350 - 500 yuan/1,000 words. 3. ** Delivery Time **: During the normal delivery period, the above standard charges will be applied. If the customer requests urgent delivery, an additional fee may be added. 4. ** Translator's Quality Requirement **: Standard quality, able to accurately convey the content of the agreement, moderate fee; High quality, accurate language, compliance with legal documents, high fee. In general, the price of the contract translation was about 200 - 500 yuan per thousand words. The specific price still needed to be confirmed in detail. In addition, the word "protocol" has different meanings in different scenarios. In the Internet industry, it has the meaning of "protocol"(for example, the full name of the IP address is Internet Protocol Address). In the political context, it is inclined to reach a political consensus, rule, or speech technique (such as political protocol). In the diplomatic context, it means a set of rules or etiquette (such as diplomatic protocol). When translating the protocol, you need to accurately understand the meaning of these words in different context. "Choose" was equally exciting. Everyone was welcome to read it!
Ipsec-esp protocol
An architecture that was designed to provide security services in a hybrid application of both the IPv4 and IPv6 networks. It provides confidentiality and integrity by encryption of the data to be protected and placing the encrypted data in its data portion. It uses a symmetrical key encryption algorithm to provide data integrity verification, data source verification, and anti-replay attack services. Depending on the user's security requirements, it can be used to encrypted the transmission layer (such as IP, IP, IGMP), or it can be used to encrypted the entire IP packet. Encapsulated protected data was necessary to provide confidentiality for the entire raw data report. The EP header can be placed after the IP header, before the upper layer protocol header (in the transport layer mode), or before the encapsulated IP header (in the tunnel mode). The protocol value assigned by Ivana to the EP header is 50. The protocol header before the EP header will contain the value 50 in the "next head" field of the IP version 6 or the "protocol" field of the IP version 4. The ESP contains a non-encrypted protocol header followed by encrypted data. The encrypted data covers the protected ESP header field and protected user data. The user data can be the entire IP datagrams or the upper layer protocol frame of the IP (for example, the protocol of a protocol such as a protocol or a protocol such as a protocol. In addition, the set of services provided by the EP is determined by the options selected and the arrangement of the implementation when the secure connection (Sa) is established. The confidentiality option is independent of other services, but using the confidentiality service without the integrity/authentication service (in the EP or in AH alone) may cause the transmission to be subject to some form of attack and destroy the confidentiality service. Data source verification and integrity of the non-connection are related services, provided to the user in combination with confidentiality (option). The anti-replay service can only be selected when the data source verification is selected, and the receiver can decide the choice of the anti-replay service alone. The novel "Dream of Silk Fate" is equally exciting. Everyone is welcome to click and read it!
The legend of free automatic recycling and automatic picking
The following are some legendary games with free automatic recycling and picking up functions: 1. "Proud Dragon City": This is a relatively pure legendary battle game. There are many types of professional characters to choose from, and there is no threshold to participate in PvP-related activities. Dungeons were unlocked according to level, and free pick-up and recycling functions were given when players went online. It could meet the needs of players to fight online at any time. 2. [The Legend of Medusa 1st Fold Version: You can receive top-tier sponsorship and a full set of zodiac gems upon logging in. You can obtain all the resources needed to level up to rank 10 upon landing. It has the function of automatic collection and recycling.] 3. "King Battleship": It has a brand new world view, 1,000 people in the same server PK competition, with a high drop rate of cross-level treasure hunting, level seal, bloody battle in the Imperial City, and full open free trade. There is also a "divine weapon" system, which can suck blood and critical hits. Its graphics were a qualitative upgrade compared to the traditional Legend of Mir 2, and the automatic collection function in the game was also free. 4. "Rejuvenation Minor Changes": It is a hot-blooded, hot-blooded, Eastern Fantasy action masterpiece. It inherits the orthodox legendary bloodline and creates a wonderful multiplayer battlefield. Fast attack speed, high critical rate, high dungeon farming efficiency, equipment that can be recycled online, ingots that can be received without delay, top-grade equipment that can be dropped from monsters, and can be used to farm gold and move bricks freely. There is also a free automatic recycling and picking function. 5. <<Berserk Legends>>: A new mobile game with a slight change in the legendary combination attack. It is a critical hit. Monsters have a chance to drop godly equipment. It has automatic picking and recycling functions. 6. "Eternal Thunder": A classic retro legendary mobile game. It can be used to reminisce the hot-blooded battle. The fully automatic picking and recycling system allows players to easily obtain equipment and enter the fierce battle. 7. <<Rampage Peerless Group>>: The new Xianxia Legend. In its fantasy game world, players can pursue the path of legend. The game is equipped with a fully automatic picking and recycling system. 8. * * The Legend of the Real Bull **: It has the characteristics of the skeleton version of the Green Poison Taoist priest. The green poison skills and skeletons of the Taoist priest help the players soar on the battlefield. There is also a fully automatic picking and recycling system. 9. "Dungeon War": A new super-legendary mobile game that can experience the legendary feeling of millions of cuts. The fully automatic picking and recycling system helps players explore and fight in the dungeons. 10. <<Hot-blooded Combined Attack>>: The 1.85 vintage legend has returned. It is integrated into the automatic pickup and recovery system, allowing players to fight without worry and relive the legendary memories. 11. "The Great God of War": Players can log in to receive a full level membership, and can easily control the automatic picking and recycling system to enjoy the fun of fighting. "The Legend of Pengcheng" is equally exciting. Everyone is welcome to click and read it!
Onvif protocol e-book
Can be found at: download.csdn.net/download/jiuyouyun/10168288? utm_source=bbsseo download the original version of the ONVIF2.0 Chinese protocol.modf. This may be the information you need about the onvif protocol e-book. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Introduction to the TTL communication protocol
Transcendence Logic was a type of circuit logic that was mainly used to control the input and output signals of computer circuits. When the circuit input receives a high-level signal, the TTL will send a low-level signal to the circuit output. It can be used to implement a variety of circuit controls, such as gate circuits, shift register, counters, and clock circuits. The standard of the TTL level was that +5V was equivalent to a logic " 1 ", and 0V was equivalent to a logic " 0 ". This method of data communication and level regulation was called the TTL signal system. Ordinary electronic devices used TTL, but some communication methods such as RS232, RS485, USB, etc. used differential signals on the transmission line. The TTL protocol is suitable for digital circuits and microchip systems, while the RS232 protocol is commonly used for computer serial communication and industrial automatic control systems. The input of a TTL circuit is usually in a high state when it is not connected because they usually have an internal pull up resistance. " Choose " was equally exciting. Everyone was welcome to read it!