DHCP relay MONitor (dhcpmon) keeps track of DORA messages. If DHCP Relay
is detected to be not forwarding DORA message, dhcpmon will log such event
to syslog. Under the hood dhcpmon keeps counts of clients DR messages,
forwarded DR messages, DHCP server OA messages, and forwarded OA messages.
dhcpmon will check every 12 sec (configurable) if counts are monotonically
increasing and record snapshot of those counters. dhcpmon will report
discrepancies when detected between current counters and snapshot counters.
pull-request: https://github.com/Azure/sonic-buildimage/pull/3886
signed-off-by: Tamer Ahmed <tamer.ahmed@microsoft.com>
