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TFTP Options and Option Negotiation
(Page 3 of 4)
TFTP Read Process With and Without Option Negotiation
The initial message exchange for
a normal read (without option negotiation), as shown in Figure 293:
- Client sends Read Request.
- Server sends Data block #1.
- Client acknowledges data block #1.
And so on…
And now, a read with option negotiation
(Figure 295):
- Client sends Read Request with
options.
- Server sends Option Acknowledgment.
- Client sends regular acknowledgment
for “block #0”, that is, it acknowledges the OACK.
- Server sends data block #1.
- Client acknowledges data block #1.
Etc…
Figure 295: TFTP Read Process With Option Negotiation This diagram shows the same example illustrated in Figure 293, but with one added message exchange used for option negotiation (purple background). The client’s initial Read Request here includes options that it wants to use for this transfer. The server responds not immediately with the first data block, but with an Option Acknowledgment. The client indicates receipt of the OACK by sending an acknowledgment using block #0. The server sends data block #1 and the rest of the exchange proceeds as normal.
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