Cambium Networks PTP 820S, Техническое описание, Страница: 93 / 208

Chapter 4: Feature Description Ethernet Features
PTP 820S performs the classification on each frame that ingresses the system via the logical
interface. Classification is performed step by step from the highest priority to the lowest priority
classification method. Once a match is found, the classifier determines the CoS and Color decision
for the frame for the logical interface-level.
For example, if the frame is an untagged IP Ethernet frame, a match will not be found until the
third priority level (DSCP priority bits). The CoS and Color values defined for the frame’s DSCP
priority bits will be applied to the frame.
Users can disable some of these classification methods by configuring them as un-trusted. For
example, if 802.1p classification is configured as un-trusted for a specific interface, the
classification mechanism does not perform classification by VLAN UP bits. This is useful, for
example, if the required classification is based on DSCP priority bits.
If no match is found at the logical interface level, the default CoS is applied to incoming frames at
this level. In this case, the Color of the frame is assumed to be Green.
The following figure illustrates the hierarchy of priorities among classification methods, from
highest (on the left) to lowest (on the right) priority.
Figure 56 Classification Method Priorities
Highest
Priority
Lowest
Priority
VLAN ID 802.1p DSCP MPLS EXP Default CoS
Interface-level classification is configured as part of the logical interface configuration. For details,
see
Ingress Path Classification at Logical Interface Level on page 4-54 .
The following tables show the default values for logical interface-level classification. The key
values for these tables are the priority bits of the respective frame encapsulation layers (VLAN, IP,
and MPLS), while the key results are the CoS and Colors calculated for incoming frames. These
results are user-configurable, but it is recommended that only advanced users must modify the
default values.
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