Comtrol ES9528-XT User Guide - Manual (Page 94)

94 - Port-Based Queue Mapping RocketLinx ES9528 and ES9528-XT User Guide: 2000508 Rev. G
Configuration Using the Web Interface
Port-Based Queue Mapping
Choose the Queue value of each port, the port then has its default priority. Queue 3 is the highest port-based
queue, 0 is the lowest queue. The traffic injected to the port follows the queue level to be forwarded, but the
outgoing traffic does not bring the queue level to the next switch.
After configuration, press Apply to enable the settings.
Note: You must Save the settings ( Page 124 ), if you want to maintain these settings if the ES9528 is powered
off.
CoS-Queue Mapping
Use this page to change the CoS values into the Physical Queue mapping table. Since the switch fabric of
ES9528 supports four queues, Lowest, Low, Middle, and High users should therefore assign how to map the
CoS value to the level of the physical queue.
You can assign the mapping table or follow the suggestion
of the IEEE 802.1p standard. The ES9528 uses IEEE
802.1p suggestion as default values. CoS Values 1 and 2
are mapped to physical Queue 0, the lowest queue. CoS
Values 0 and 3 are mapped to physical Queue 1, the low/
normal physical queue. CoS Values 4 and 5 are mapped to
physical Queue 2, the middle physical queue. CoS Values
6 and 7 are mapped to physical Queue 3, the high
physical queue.
Class of service (CoS) is a 3 bit field within a layer two
Ethernet frame header defined by IEEE 802.1p when
using IEEE 802.1Q tagging. The field specifies a priority value of between 0 and 7 inclusive that can be used
by Quality of Service (QoS) disciplines to differentiate traffic.
While CoS operates only on Ethernet at the data link layer, other QoS mechanisms (such as DiffServ) operate
at the network layer and higher. Others operate on other physical layers. Although IEEE 802.1Q tagging
must be enabled to communicate priority information from switch to switch, some switches use CoS to
internally classify traffic for QoS purposes.
Differentiated Services (DiffServ) is a model where traffic is treated by intermediate systems with relative
priorities based on the type of services (ToS) field. Defined in RFC2474 and RFC2475, the DiffServ standard
supersedes the original specification for defining packet priority described in RFC791. DiffServ increases the
number of definable priority levels by reallocating bits of an IP packet for priority marking. The DiffServ
architecture defines the DiffServ field, which supersedes the ToS field in IPv4 to make per-hop behavior
(PHB) decisions about packet classification and traffic conditioning functions, such as; metering, marking,
shaping, and policing.