DRA-2 UNIVERSAL COMMUNICATION NODE
61/158
USER GUIDE - Rev.5 (January 2018)
5.5
QoS CONFIGURATION
The Quality of Service (QoS) permits the classification of the packets in data queues and
the service policy for them.
The equipment provides QoS at level 2 (switching) and level 3 (routing). The QoS facilities
of both levels are independent from each other, but the fact that they share the possibility of
using the DSCP parameter enables coherent behaviours to be obtained at both levels.
5.5.1
QoS Layer 2
Level 2 QoS is performed on switched traffic, adjusted to the processing of parameters and
behaviour of IEEE 802.1p, with three internal priority levels. This priority is taken into
account for establishing the processing and transmission order in each switch output
interface.
Two potential service policies are admitted in processing the queues for each priority:
Priority
or
Weight Fair Scheduling
(WFQ)
. The
Priority
policy only serves a queue with a
lower priority when the higher priority queues are empty. The
WFQ
policy guarantees a
weighted service for all the priority, but preeminently to queues with a high priority.
The service policy is unique for level 2 service. The parameters are the VLAN and priority
802.1p (included in the tag or assigned depending on the input port) or the DSCP field of
level 3.
The priority supported by standard 802.1p admits values of between 0 and 7. The untagged
frames received are given a priority within that range, depending on the interface through
which they were received, pursuant to the section entitled
QoS Layer 2 (ports)
. Tagged
frames may include both the VLAN identifier as the priority (tagged) or only the priority
(priority tagged, VLAN = 0). If the VLAN identifier is included, they are processed in
accordance with the rules of the section entitled
QoS Layer 2 (VLANs)
. If, on the contrary,
they only include the priority, they are processed in accordance with the section entitled
QoS Layer 2 (ports).
In all cases, with the except for assigning by DSCP which is done directly on the internal
queues, the priority assigned is used for the final classification, as indicated in the section
VLAN Priority Mapping.
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