Congestion Management; Queue Sets - Alcatel-Lucent OmniSwitch 9900 Series Network Configuration Manual

Configuring QoS

Congestion Management

Queuing mechanisms are used to manage congestion on egress ports. When congestion occurs, packets are
prioritized and placed into queues based on the CoS markings assigned to the packets during
classification. If there is no congestion on the egress port, packets are sent out as soon as they are received.
There are eight egress queues allocated for each port on an OmniSwitch. Queue Set Profiles (QSPs) or
Data Center Bridging (DCB) profiles are used to provide traffic management and QoS scheduling for the
egress queues. For more information, see

Queue Sets

The queue management and related QoS functions are implemented using a framework based on Queue
Sets (QSets). A QSet is a set of eight egress port queues that are associated with each switch port.
The QSET framework involves the following elements:
•
QSet instance (QSI)—A QSI is a logical entity that refers to a set of eight queues. Each port in the
switch is automatically associated with a QSI.
•
QSet profile (QSP)—a profile associated with each QSI that defines the output scheduling behavior
for the queues associated with the QSet instance. There are four pre-defined QSPs, with QSP 1 serving
as the default profile that is automatically assigned to each QSI. See
Note. The OmniSwitch 9900 supports only two QSet profiles: QSP 1 and QSP 5. The QSP 5 profile,
however, is not supported on the other OmniSwitch platforms.
•
Data Center Bridging profile (DCP)—a profile associated with each QSI that defines the output
scheduling behavior for the queues associated with the QSet instance. Note that the OmniSwitch 9900
does not support Data Center Bridging.
There are eleven pre-defined DCPs, with DCP 8 serving as the default profile that is automatically
assigned to each QSI. DCB profiles are only applied when the switch is using the OmniSwitch Data
Center license. See the "Configuring Data Center Bridging" chapter in the OmniSwitch AOS Release 8
Data Center Switching Guide.
Note. QSet profiles and DCB profiles are mutually exclusive. If the OmniSwitch Data Center software
license is installed, then DCB profiles are used. If this license is not installed, then QSet profiles are used.
•
Weighted Random Early Detection (WRED) profile—a WRED profile (WRP) is associated with
each QSet profile to provide admission control for each QSet. One WRP is supported on the
OmniSwitch 6900 (WRP 1), which is the default profile automatically assigned to each QSP. See
"WRED Profiles" on page 26-15
How it Works
When a physical switch port comes up, a QSet instance (a set of eight queues) is automatically associated
with the port for unicast traffic. In addition, the default QSet profile (QSP 1) or the default DCB profile
(DCP 8) is automatically assigned to the QSI. In the case where QSP 1 is assigned, the default WRED
profile (WRP 1) is automatically imported as part of QSP 1.
If a port attaches to a link aggregate (LAG), a QSI and default QSP 1 or default DCP 8 are automatically
associated with the LAG ID. Each time a port joins the LAG, the QSI for the port is imported into the
OmniSwitch AOS Release 8 Network Configuration Guide
"Queue Sets" on page 26-9
Note that WRED is supported only on the OmniSwitch 6900.
December 2017
Congestion Management
and "QSet Profiles" on page
"QSet Profiles" on page
26-11.
26-11.
page 26-9