3.8 Sequence Numbers

The MDFU Protocol utilizes command-response pairs to transfer signals and data between the host and client. Sequence numbers provide a way for the host/client to specifically identify commands and responses as being part of a command-response pair. The sequence fields also provide some additional control information.

Sequence numbers allow the following functionality:

1. Hosts can properly associate responses from the client with specific commands that were sent from the hosts.
2. Clients can ensure that all commands are executed in the proper order and are only executed once.
3. Clients can request a specific corrupted command be resent by the host.
4. Hosts can request a corrupted response be resent without triggering a repeated command execution.

Please refer to the following sections for the host’s algorithm for determining the sequence field value for commands and the client’s algorithm for processing sequence numbers.