ECS4110-28P_Management Guide

C HAPTER 10 | Class of Service
Layer 3/4 Priority Settings
– 281 –
Figure 132: Setting the Trust Mode
MAPPING INGRESS
DSCP VALUES TO
INTERNAL DSCP
VALUES
Use the Traffic > Priority > DSCP to DSCP page to map DSCP values in
incoming packets to per-hop behavior and drop precedence values for
internal priority processing.
The DSCP is six bits wide, allowing coding for up to 64 different forwarding
behaviors. The DSCP replaces the ToS bits, but it retains backward
compatibility with the three precedence bits so that non-DSCP compliant,
ToS-enabled devices, will not conflict with the DSCP mapping. Based on
network policies, different kinds of traffic can be marked for different kinds
of forwarding.
CLI REFERENCES
◆ "qos map dscp-mutation" on page 1202
COMMAND USAGE
◆ Enter per-hop behavior and drop precedence for any of the DSCP
values 0 - 63.
◆ This map is only used when the priority mapping mode is set to DSCP
(see page 280), and the ingress packet type is IPv4. Any attempt to
configure the DSCP mutation map will not be accepted by the switch,
unless the trust mode has been set to DSCP.
◆ Two QoS domains can have different DSCP definitions, so the DSCP-to-
PHB/Drop Precedence mutation map can be used to modify one set of
DSCP values to match the definition of another domain. The mutation
map should be applied at the receiving port (ingress mutation) at the
boundary of a QoS administrative domain.
PARAMETERS
These parameters are displayed:
◆ DSCP – DSCP value in ingress packets. (Range: 0-63)
◆ PHB – Per-hop behavior, or the priority used for this router hop.
(Range: 0-7)