nak naks

the data packet sequence number is correct, if the result is not 0, the Nak request will be re-transmitted.After the receiver confirms that the data packet sequence number is correct, it then checks whether the sequence number is expected. If it is not the expected data packet sequence number, it indicates a serious error, you should send a can to stop the transmission.If the number of packets received is the same as that of the previous packet, the

is:Receive send1 1 1 1 1 1 1 0 FEH 0 0 0 0 0 1 0 1 05H 0 0 0 0 0 1 1 1 07H 1 0 0 0 0 1 0 1 0--0000 1010The check code is also 0AH. It can be seen that when there are 2 changes in the data, the receiver calculates the check code is still consistent with the sender, this check method cannot detect the error of even bits.The checksum of the XMODEM protocol only calculates 128 bytes of data in the data frame, and the head 3 bytes do not participate in the checksum operation. 2.4 Xmodem protocol St

several configuration Request packets (Config-Request packets) consecutively, and the data domains of these Request packets may be identical, they only have different identification domains. Generally, the ID of a configured request packet is gradually increased by 1 from 0x01. When the peer receives the configured request packet, no matter which type of message is used, one of the three messages may be Config-Ack, Config-Nak, and Config-Reject) to b

Source: Kermit,xmodem,ymodem,zmodem Transport Protocol SummaryKermit protocolMessage format:1.MARK, starting Mark Start_char, for 0x01 (CTRIL-A);2.LEN, the length of the remainder of the message, the value range 0~94, the maximum length of the message 96, the length does not include newline characters or tabs;3.SEQ, packet number, modulo 64,;4.type,k_state Packet Type D Data message TD valign= "Top" width= " Y valign= "Top" width= "217"

Package number Take back plus 1 1024 Data segments and DescriptionThe opening byte of the SOH frame, which represents the first byte in the packetPacket Sequence Number: to the 256 modulus to the current package number, the first packet is 1, and the packet sequence range 0~255;The complement of the information packet ordinal: the complement of the current information packet number;Data segment: The length of the data segment is fixed to 128 bytes (the last segmen

received, it means that the DATA1 packet is omitted and the error condition is generated. DATA2 and Mdata, however, are only suitable for high-speed, equal-time transmissions.If the host wants to set each endpoint for the special addressing, send out the command to set each descriptor, as shown in 4, the data packet containing the command will be outgoing. In particular, it is important to note that there are only 8 bytes in the data domain because of the control transfer. The meaning of the eq

data bit, which can be 8 to 192 digits at most. The data should be an integer multiple of the bytes. Crcl6 is a 16-bit CRC verification code for data domain verification. The verification polynomials are: g (x) = x16 + x15 + X2 + 1. 3) handshake packet formatA handshake package is used to indicate the transaction status, such as the successful receipt of data, the receipt of commands, and the rejection. The handshake package format is 10.35.A handshake package consists of only PII. There ar

the packet identity, data is a bit, up to 8 192 bits, and data should be an integer multiple of bytes. The CRCL6 is a 16-bit CRC checksum that verifies the data domain, and the checksum polynomial is: G (X) =x16+x15+x2+1.3) Handshake Package formatThe handshake packet is used to indicate that the data was successfully received, that the command was received or rejected, and so on. Handshake package Format 10. As shown in 35.The handshake package consists only of PII. There are four commonly use

. PID data transfer Direction In Device->host Out Host->device SETUP Host->device PING device->host 1.3 start-of-frame (SOF) Packets The SOF package is sent to device by the host.1 for Full-speed bus, every 1.00 ms±0.0005 ms send once;2) for high-speed bus, send once every 125μs±0.0625μs;The SOF package consists of the following figure: 1.4 Data Packets There are four types of packets: DATA0, DATA1, Data2,and mdata, and are differentiated by PID. DATA0 and DATA1 are defined to support data-swi

packet format is 10.34.The PID is the package ID, and data is the data bit, which can be 8 to 192 digits at most. The data should be an integer multiple of the bytes. Crcl6 is a 16-bit CRC verification code for data domain verification. The verification polynomials are: g (x) = x16 + x15 + X2 + 1.3) handshake packet formatA handshake package is used to indicate the transaction status, such as the successful receipt of data, the receipt of commands, and the rejection. The handshake package forma

protocol is a Point-to-Point Protocol, no MAC address of the Ethernet is required for the PPP protocol.Protocol used to mark data in packaged packetsI will not talk about the IP protocol. I will focus on the above four protocols.LCP ProtocolCode field: indicates "sub-Protocol"Id field: equivalent to the Message ID.Length field: length field content = total bytes of data (code field + sign field + length field + data field ). Bytes other than the number of characters indicated by the length fiel

DAT_WR_BYTE (x) (0x00000100 | ((x) #define CMD_SEL_EP (x) (0x00000500 | ((x) #define DAT_SEL_EP (x) (0x00000200 | ((x) #define CMD_SEL_EP_CLRI (x) (0x00400500 | ((x) #define DAT_SEL_EP_CLRI (x) (0x00400200 | ((x) #define CMD_SET_EP_STAT (x) (0x00400500 | ((x) #define CMD_CLR_BUF 0x00f20500#define DAT_CLR_BUF 0x00f20200//usb Clear the endpoint buffer#define CMD_VALID_BUF 0x00fa0500//ACK buffer, when the command is sent, tells the endpoint when the next in packet to send the endpoint buffer data

mac address of the Ethernet is required for the ppp protocol.Protocol used to mark data in packaged packetsI will not talk about the IP protocol. I will focus on the above four protocols.LCP ProtocolCode field: indicates "sub-Protocol"ID field: equivalent to the Message ID.Length field: length field content = total bytes of data (code field + sign field + length field + data field ). Bytes other than the number of characters indicated by the length field will be ignored as the padding byte.LCP

Ethernet is required for the ppp protocol.Protocol used to mark data in packaged packetsI will not talk about the IP protocol. I will focus on the above four protocols.LCP ProtocolCode field: indicates "sub-Protocol"ID field: equivalent to the Message ID.Length field: length field content = total bytes of data (code field + sign field + length field + data field ). Bytes other than the number of characters indicated by the length field will be ignored as the padding byte.LCP Data Packet Classif

useless.7, set the SLWR is active high, the other is low-level active. Set by Portacfg and Fifopinpolar registers.PortacfgThe Portacfg |=0x40 indicates that the SLCS is set to the multiplexed pin function and is active at low levels.Fifopinpolar0 indicates low active1 indicates active high levelHere Fifopinpolar = 0x07 The SLWR is set to high, the remaining settings are active low.8. Endpoint 2 autoin data length settingSet ep2autoinlenh = 0x02;//packet length high byte, auto transfer packet si

Enq Did Did Alert ACK Alert Nak Alert Soh Sid Did Did CP Data

reliable data transmission services naturally relies on reliable data transmission protocols. We need to study a series of protocols, from simple to complex, one by one. 1. Reliable data transmission over fully reliable channels rdt 1.0, that is, the underlying layer is completely reliable. The sender sends data, and the receiver receives the data. No feedback is required between the two because the data is completely reliable. 2. Reliable data transmission over Bits Error channels rdt 2.0 the

transmission via a bit error channel Positive confirmation (positive acknowledgment) Denial of confirmation (negative acknowledgment) These control messages allow the receiver to let the sender know what is being received correctly, which content is being received incorrectly and therefore needs to be duplicated. In the computer network environment, the reliable data transmission protocol based on such retransmission mechanism is called automatic retransmission request (Automatic Repeat Request

When dhcpclient switches between different dhcpsevers at a time, packet capture records the author's dhcpclient switches between different dhcpsevers at a time (from 10.0.2. amp; times; network segment to 10.0.9.x network segment). The number of the fourth packet NAK in www.2cto.com is as follows... packet capture records when a dhcp client switches between different dhcp sever The author's dhcp client switches between different dhcp sever at one tim

type (i.e. package type)1.2 Token PacketsThis format applies to In, out, SETUP, PING.PID Data transmission DirectionIn Device->hostOut Host->deviceSETUP Host->devicePING Device->host1.3 Start-of-frame (SOF) PacketsThe SOF package is sent to device by host.1) for Full-speed bus, every 1.00 ms±0.0005 MS is sent once;2) for high-speed bus, send once every 125μs±0.0625μs;The SOF package is composed as shown in:1.4 Data PacketsThere are four types of packets: DATA0, DATA1, Data2,and mdata, and are d