Switchd is the bridge between the linux kernel and the hardware.  It has
two main jobs:
1) Providing linux network interfaces for each front-panel port.
2) Synchronizing changing kernel network state (link state, routes,
   neighbor tables, etc) with the hardware.

It should be started using its init.d script.  See /etc/default/switchd.

COMMAND LINE INVOCATION:
usage: switchd [OPTIONS]
OPTIONS:
    -d: detach and become a daemon
    -do: launch in non-operational diagnostic only mode
    -V: Display switchd version information

CONFIGURATION:
Persistent configuration is managed in /etc/cumulus/switchd.conf.  Run-
time configuration is reflected in /cumulus/switchd/config.

ENVIRONMENT VARIABLES:
 ITIMER: If set, switchd will log timing information.
 BCM_CONFIG_FILE: Specifies a non-default location for config.bcm.
 NUM_DUMMIES: Tells switchd to create dummy backends for testing.
