tree 2cee2b4e3cf25fc531024647455acbe769ac4e4a
parent cac7eb1ca5a3b9f318ab9a6a51af6dc14a393381
author Peter Qiu <zqiu@chromium.org> 1421965523 -0800
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> 1422306121 +0000

shill: reduce ARP traffic from LinkMonitor

This is achieved by monitoring the link passively (monitor on ARP requests)
after the link is determined as up via active link monitor (sending
ARP requests and probing for ARP replies). Only switch to active link
monitor when the passive link monitor completes after a preset number
of successful cycles or after a single failed cycle.

ARP traffic will be reduced since the device will not be generating
any ARP requests during passive link monitoring period. This will potentially
delay the detection of link failure up to one passive monitoring cycle
(25 seconds) when the link goes down during passive monitoring.

BUG=chromium:422159
TEST=USE="asan clang" FEATURES=test emerge-$BOARD shill
     Connect DUT to a wireless network, and verify link monitor mode switching
     via debug logs

Change-Id: I4c72a048da18cee7dc5be2cf2b51082cb9ae6716
Reviewed-on: https://chromium-review.googlesource.com/242684
Tested-by: Zeping Qiu <zqiu@chromium.org>
Reviewed-by: Zeping Qiu <zqiu@chromium.org>
Commit-Queue: Zeping Qiu <zqiu@chromium.org>