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When connect a USB 2.0 external IDE HDD to a laptop, what is the stack of protocols for communication between the laptop and the external HDD?

Is it similar in a way to OSI model in network? If I understand correctly, in OSI model for network, there are two hosts, each of which has the same layers/levels of protocols. On each host, messages must goes from top to the lowest, and the communication between the two hosts is through the lowest level of protocol.

My question arose from comments with Gilles here.


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Beware that the "OSI model" is conceptual, and many protocol stacks (incl. TCP/IP) do not implement every layer as a distinct, identifiable layer. "in OSI model for network, there are a host and a client" - I've never noticed that concept. How would a "peer-to-peer" connection fit into that scheme? I.E. You seem to be putting words into the model that are not there. –  sawdust Aug 19 '12 at 22:34
Yes, it can be peer to peer too. How would you say for both host-client and peer-to-peer? –  Tim Aug 19 '12 at 22:38
"How would you say for both host-client and peer-to-peer?" - Probably just say it's a "host-to-host" network connection, which normally does not denote any hierarchy. You seem to be be misusing "host"; in networking "node" and "host" are often used interchangeably. The word you probably meant was "server", as in "server & client". The USB protocol does use the term "host" in a hierarchical sense, but networking does not use "host" the same way. IOW beware the context when you use the word "host". –  sawdust Aug 19 '12 at 22:59
What is opposite of host, as client to server? peripheral? –  Tim Aug 19 '12 at 23:00
"What is opposite of host?" - In USB the opposite of "host" is "gadget" or "device". In networking, I think there really is no opposite or complementary entity. There are nodes that are not hosts and there are links, but those are just "other" network entities, and not necessarily "opposite". Note that I stated the context when using the word "host", unlike your (ambiguous) question. –  sawdust Aug 19 '12 at 23:15

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