wifi codelab: Add better descriptions for 802.11 stuff
I received some feedback on this codelab that without some
background context, it was difficult to understand the
802.11 concepts like Association, Authentication, and the
various management frames. Add extra explanations for these
concepts.
BUG=chromium:1010953
TEST=`${CROS_ROOT}/docs/scripts/preview_docs
./docs/wifi-basics-codelab.md` verify rendering. Use mdl to lint.
Completed the codelab successfully.
Change-Id: I1d568efa3835c2060109a095e9ad2b046c4ca20f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1919647
Reviewed-by: Trent Begin <tbegin@chromium.org>
Reviewed-by: Shuo-Peng Liao <deanliao@chromium.org>
Tested-by: Kevin Lund <kglund@google.com>
Commit-Queue: Kevin Lund <kglund@google.com>
diff --git a/docs/wifi-basics-codelab.md b/docs/wifi-basics-codelab.md
index 9b21cae..63714f3 100644
--- a/docs/wifi-basics-codelab.md
+++ b/docs/wifi-basics-codelab.md
@@ -243,12 +243,38 @@
+##### Authentication and Association
+
+In order to ensure security, users must be authenticated to a network before
+they are allowed to use the network. The authentication process itself is not
+strictly defined by the 802.11 protocol, but it usually consists of a robust
+cryptographic exchange that allows the network to trust the user. Once a user
+has been authenticated to the network, it is *trusted*, but it is still not
+actually a member of the network until it has been *associated*. Association
+can be thought of as the proccess of actually joining the network, and also
+acts as a sort of *registration* that allows the network to determine which
+access point to use for a given user.
+
##### Class 1 frames
Class 1 frames can be sent in any state, and they are used to support the basic
operations of 802.11 connections. Class 1 frames are called *Management Frames*
-and they allow devices to find a network and authenticate to it. Beacons,
-association requests, and probe requests are examples of Class 1 frames.
+and they allow devices to find a network and negotiate their connection status.
+
+**Some class 1 frames:**
+
+* *Beacons* are frames that access points send out on a regular interval to
+broadcast their existence to the world. Devices are only aware of access points
+because they can see the beacon frames they send.
+* Devices respond to beacons with *Probe Requests* which in turn let the
+network know of their existence. The probe request also includes a list of all
+data rates the device supports, which the network can use to check for
+compatability with those supported by the access point.
+* Access points respond with *Probe Responses* which either confirm or deny
+compatability.
+* If the two are compatable, they can engage in the authentication/association
+process as explained above with various *Association* and *Authentication*
+frames.
##### Class 2 frames