This MIB module extends the CISCO-CLASS-BASED-QOS-MIB
by defining configuration and statistics information
specific to the quality of service (QoS) features of
Layer2/3 switch functionality implemented in Cisco
devices. It is applicable to a device which is fully
within a single QoS domain, although one or more
boundaries with other QoS domains can be immediately
adjacent to this device.

Configuration information available through this MIB
includes:

+ Mappings between CoS, IP Precedence, MPLS-EXP value
  to DSCP value and vice versa for classification purpose.

+ Device level QoS configuration for DSCP rewrite,
  policing of ACL-redirected traffic, QoS port-queueing
  mode, statistics collection for policy that sets a 
  trust state. 

+ CoS, MPLS-EXP and DSCP mutation map name and mappings.
  These mutations can be configured so that they change
  the content of packets which cross QoS boundaries, either
  as they enter or leave this device. 

+ Interface QoS configuration such as default CoS value,
  trust state, packet assignment to queue and threshold
  based on CoS or DSCP value, drop algorithm and
  corresponding parameters, queue scheduling parameter
  such as WRR (Weighted Round Robin) weights, queue
  size allocation weight.

Statistics available through this MIB includes:

+ Per module Multi-Layer Switching QoS statistics.

+ Per interface QoS queueing statistics.

The following terms are used throughout this MIB:

DSCP (Differentiated Services Code Point) is the six most
significant bits of the ToS field in a IP packet header.

DSCP Mutation: when a packet is being forwarded across an
IP network, the previous hop(s) and the following hop(s)
of a device may reside in a different QoS domain. A QoS
domain refers to the set of QoS rules and conventions
adopted by an administrative entity. For instance, a set
of DSCP values may have a different meaning in different
domains. DSCP mutation allows a DSCP set to be mutated or
transformed in order to maintain semantic compatibility
between adjacent domains. The mutation is done via mapping
tables which maps the old DSCP value from one domain to a
new DSCP value in the other domain. DSCP Mutation is applied 
to egress traffic.

IP precedence is the three most significant bits of the ToS
field in a IP packet header.

CoS (Class of Service) is the three bits in the layer 2
header that indicates user priority value assigned to this
packet.

Trust state is a parameter configured at an interface to
specify which QoS markings in packets arriving at that
interface are acceptable as-is, rather than needing to be
ignored/overwritten due to an 'untrusted' source or
previous hop.

BPDU (Bridge Protocol Data Unit) is used by bridges 
in a network to exchange information regarding their
status. The Spanning Tree Protocol uses the BPDU
information to elect the root switch and root port
for the switched network.

MPLS-EXP:  MPLS experimental field in MPLS label.

MTU: Maximum Transmission Unit.