Ask for a data block size in the request
01The Trivial File Transfer Protocol (TFTP) normally sends up to 512 data octets at a time. A client can append blksize to a Read Request (RRQ) or Write Request (WRQ) before data transfer.
Value 1428 permits 1428 data octets, plus a separate four-octet DATA header. It does not mean a whole packet of 1428 bytes. Valid requested values include both endpoints 8 and 65464.
Source for this drawing: RFC 2348 · Read RFC source: Blocksize option · p.1 ↗
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The requested block size is ASCII decimal from 8 through 65464 inclusive. It counts DATA octets only, excluding the four-octet TFTP DATA header.
- The requested block size is ASCII decimal from 8 through 65464 inclusive. It counts DATA octets only, excluding the four-octet TFTP DATA header.
- The two-octet opcode is binary: 1 for RRQ, 2 for WRQ. Filename, mode, option name and value are zero-terminated strings; blksize is case-insensitive.
- The example uses octet (binary) mode and the published filename foobar with value 1428. This is a chosen value, not a universal Ethernet maximum. RFC 2347 bounds a request to 512 octets and permits each option only once.
A selected octet-mode example, not a complete TFTP implementation. One octet is an eight-bit byte. Follow the actual RFC source and its companion option-negotiation rules.
Read the RFC section ↗