Copyright 2014, 2015, 2016, 2017, Cumulus Networks, Inc.  All rights reserved.

Hardware datapath configuration manages packet buffering, queueing, and scheduling
in hardware.  There are two configuration input files:

* /etc/cumulus/datapath/traffic.conf: describes priority groups and assigns
  the scheduling algorithm and weights

* /etc/bcm.d/datapath/datapath.conf: assigns buffer space and egress queues

Each packet is assigned to an ASIC Class of Service (CoS) value based on the packet's
priority value stored in the 802.1p (Class of Service) or DSCP (Differentiated
Services Code Point) header field.  The packet is assigned to a Priority Group
based on the CoS value.

Priority groups include:

* Control: Highest priority traffic
* Service: Second-highest priority traffic
* Lossless: Traffic protected by priority flow control
* Bulk: All remaining traffic

A lossless priority group requires a port group configuration which specifies
the ports configured for priority flow control and the additional buffer space
assigned to each port for packets in the lossless priority group.

