📄 rfc783.2up.ps
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(ACK packets are acknowledged by DATA or ERROR packets. Figure 5-3) s5 556 M(depicts an ACK packet; the opcode is 4. The block number in an ACK) s5 530 M(echoes the block number of the DATA packet being acknowledged. A WRQ is) s5 504 M(acknowledged with an ACK packet having a block number of zero.) s5 478 M( Figure 5-4: ERROR packet) s5 413 M( 2 bytes 2 bytes string 1 byte) s5 400 M( -----------------------------------------) s5 387 M( | Opcode | ErrorCode | ErrMsg | 0 |) s5 374 M( -----------------------------------------) s5 322 M( An ERROR packet \(opcode 5\) takes the form depicted in Figure 5-4. An) s5 296 M(ERROR packet can be the acknowledgment of any other type of packet. The) s5 270 M(error code is an integer indicating the nature of the error. A table of) s5 244 M(values and meanings is given in the appendix. \(Note that several error) s5 218 M(codes have been added to this version of this document.\) The error) s5 192 M(message is intended for human consumption, and should be in netascii.) s5 166 M(Like all other strings, it is terminated with a zero byte.) s5 49 M( 12) s_R%Page: (14) 14%BeginPageSetup_S% N-up sub-page 2/2402 -547 translate0.688917 dup scale/pagenum 14 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (14) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 14 of 20) def%%EndPageSetupdo_header5 725 M(6. Normal Termination) s5 699 M( The end of a transfer is marked by a DATA packet that contains between) s5 673 M(0 and 511 bytes of data \(i.e. Datagram length < 516\). This packet is) s5 647 M(acknowledged by an ACK packet like all other DATA packets. The host) s5 621 M(acknowledging the final DATA packet may terminate its side of the) s5 595 M(connection on sending the final ACK. On the other hand, dallying is) s5 569 M(encouraged. This means that the host sending the final ACK will wait) s5 543 M(for a while before terminating in order to retransmit the final ACK if) s5 517 M(it has been lost. The acknowledger will know that the ACK has been lost) s5 491 M(if it receives the final DATA packet again. The host sending the last) s5 465 M(DATA must retransmit it until the packet is acknowledged or the sending) s5 439 M(host times out. If the response is an ACK, the transmission was) s5 413 M(completed successfully. If the sender of the data times out and is not) s5 387 M(prepared to retransmit any more, the transfer may still have been) s5 361 M(completed successfully, after which the acknowledger or network may have) s5 335 M(experienced a problem. It is also possible in this case that the) s5 309 M(transfer was unsuccessful. In any case, the connection has been closed.) s5 257 M(7. Premature Termination) s5 231 M( If a request can not be granted, or some error occurs during the) s5 205 M(transfer, then an ERROR packet \(opcode 5\) is sent. This is only a) s5 179 M(courtesy since it will not be retransmitted or acknowledged, so it may) s5 153 M(never be received. Timeouts must also be used to detect errors.) s5 75 M( 13) s_R_RS%%Page: (15-16) 8%%BeginPageSetup_S90 rotate24 -24 translate%Page: (15) 15%BeginPageSetup_S% N-up sub-page 1/20 -547 translate0.688917 dup scale/pagenum 15 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (15) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 15 of 20) def%%EndPageSetupdo_header5 725 M(I. Appendix) s5 686 M(Order of Headers) s5 647 M( 2 bytes) s5 634 M( ----------------------------------------------------------) s5 621 M(| Local Medium | Internet | Datagram | TFTP Opcode |) s5 608 M( ----------------------------------------------------------) s5 569 M(TFTP Formats) s5 530 M(Type Op # Format without header) s5 517 M( 2 bytes string 1 byte string 1 byte) s5 504 M( -----------------------------------------------) s5 491 M(RRQ/ | 01/02 | Filename | 0 | Mode | 0 |) s5 478 M(WRQ -----------------------------------------------) s5 465 M( 2 bytes 2 bytes n bytes) s5 452 M( ---------------------------------) s5 439 M(DATA | 03 | Block # | Data |) s5 426 M( ---------------------------------) s5 413 M( 2 bytes 2 bytes) s5 400 M( -------------------) s5 387 M(ACK | 04 | Block # |) s5 374 M( --------------------) s5 361 M( 2 bytes 2 bytes string 1 byte) s5 348 M( ----------------------------------------) s5 335 M(ERROR | 05 | ErrorCode | ErrMsg | 0 |) s5 322 M( ----------------------------------------) s5 101 M(\\026) s5 75 M( 14) s_R%Page: (16) 16%BeginPageSetup_S% N-up sub-page 2/2402 -547 translate0.688917 dup scale/pagenum 16 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (16) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 16 of 20) def%%EndPageSetupdo_header5 725 M(Initial Connection Protocol for reading a file) s5 686 M( 1. Host A sends a "RRQ" to host B with source= A's TID,) s5 673 M( destination= 69.) s5 647 M( 2. Host B sends a "DATA" \(with block number= 1\) to host A with) s5 634 M( source= B's TID, destination= A's TID.) s5 36 M( 15) s_R_RS%%Page: (17-18) 9%%BeginPageSetup_S90 rotate24 -24 translate%Page: (17) 17%BeginPageSetup_S% N-up sub-page 1/20 -547 translate0.688917 dup scale/pagenum 17 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (17) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 17 of 20) def%%EndPageSetupdo_header5 725 M(Error Codes) s5 686 M(Value Meaning) s5 673 M(0 Not defined, see error message \(if any\).) s5 660 M(1 File not found.) s5 647 M(2 Access violation.) s5 634 M(3 Disk full or allocation exceeded.) s5 621 M(4 Illegal TFTP operation.) s5 608 M(5 Unknown transfer ID.) s5 595 M(6 File already exists.) s5 582 M(7 No such user.) s5 23 M( 16) s_R%Page: (18) 18%BeginPageSetup_S% N-up sub-page 2/2402 -547 translate0.688917 dup scale/pagenum 18 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (18) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 18 of 20) def%%EndPageSetupdo_header5 738 M( 3) s5 725 M(Internet User Datagram Header [2] ) s5 686 M( Format) s5 660 M( 0 1 2 3) s5 647 M( 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1) s5 634 M(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 621 M(| Source Port | Destination Port |) s5 608 M(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 595 M(| Length | Checksum |) s5 582 M(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 543 M(Values of Fields) s5 504 M(Source Port Picked by originator of packet.) s5 465 M(Dest. Port Picked by destination machine \(69 for RRQ or WRQ\).) s5 426 M(Length Number of bytes in packet after Datagram header.) s5 400 M( 4) s5 387 M(Checksum Reference 2 describes rules for computing checksum. ) s5 374 M( Field contains zero if unused.) s5 335 M(Note: TFTP passes transfer identifiers \(TID's\) to the Internet User) s5 309 M(Datagram protocol to be used as the source and destination ports.) s5 140 M(_______________) s5 127 M( 3) s5 114 M( This has been included only for convenience. TFTP need not be) s5 101 M(implemented on top of the Internet User Datagram Protocol.) s5 88 M( 4) s5 75 M( The implementor of this should be sure that the correct algorithm is) s5 62 M(used here.) s5 23 M( 17) s_R_RS%%Page: (19-20) 10%%BeginPageSetup_S90 rotate24 -24 translate%Page: (19) 19%BeginPageSetup_S% N-up sub-page 1/20 -547 translate0.688917 dup scale/pagenum 19 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (19) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 19 of 20) def%%EndPageSetupdo_header5 725 M(References) s5 699 M( [1] USA Standard Code for Information Interchange, USASI X3.4-) s5 673 M( 1968.) s5 621 M( [2] Postel, Jon., "User Datagram Protocol," RFC768, August 28,) s5 595 M( 1980.) s5 556 M( ) s5 543 M( [3] "Telnet Protocol Specification," RFC764, June, 1980.) s5 49 M( 18) s_R%Page: (20) 20%BeginPageSetup_S% N-up sub-page 2/2402 -547 translate0.688917 dup scale/pagenum 20 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc783.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc783.txt) def% User defined strings:/fmodstr (Thu Oct 15 00:00:00 1992) def/pagenumstr (20) def/user_header_p true def/user_header_left_str (RFC783) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 20 of 20) def%%EndPageSetupdo_header_R_RS%%Trailer%%Pages: 20%%DocumentNeededResources: font Courier Times-Italic %%EOF⌨️ 快捷键说明
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