Append option pairs to a read or write request
01TFTP means Trivial File Transfer Protocol. Its client reads a file using RRQ or writes one using WRQ. Options are extra named settings appended to that original request.
Separate size comparison: an otherwise valid constructed request can total exactly 512 octets. A 513-octet request exceeds the limit even if its option suffix is short.
Source for this drawing: RFC 2347 · Read RFC source: Packet Formats · p.2 ↗
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The two-octet opcode is 1 for RRQ and 2 for WRQ. Filename and transfer mode remain at the front; this guide uses octet mode for unchanged file bytes.
- The two-octet opcode is 1 for RRQ and 2 for WRQ. Filename and transfer mode remain at the front; this guide uses octet mode for unchanged file bytes.
- Each option name and value is a separate case-insensitive ASCII string terminated by a zero octet. A zero terminator is byte 00, not the printable digit 0 (byte 30 hexadecimal). Do not apply option case folding to a filename.
- Several pairs can be appended; their order has no significance. Each option may be specified only once, including case variants of the same name.
- The entire request packet has a maximum of 512 octets, including opcode, filename, mode and all zero-terminated pairs. This is not a 512-octet allowance just for options; UDP/IP headers are outside this packet limit.
Fictional picnic.txt in octet mode; chosen sizes and values are examples. Comparisons reset state. This RFC uses lowercase must/should/may; those distinctions are retained. No real files or UDP transfers are used.
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