System information

174 | Chapter 6: Configuring Quality of Service
GS752TXS Smart Switch Software Administration Manual
To configure CoS settings for an interface:
1. To configure CoS settings for a physical port, click PORTS.
2. To configure CoS settings for a Link Aggregation Group (LAG), click LAGS.
3. To configure CoS settings for both physical ports and LAGs, click ALL.
4. Select the check box next to the port or LAG to configure. You can select multiple ports and
LAGs to apply the same setting to the selected interfaces.
5. From the Interface Trust Mode field, specify whether the selected interface(s) trust a
particular packet marking when the packet enters the port.
• Untrusted. Do not trust any CoS packet marking at ingress.
• 802.1p. The eight priority tags that are specified in IEEE 802.1p are p0 to p7. The
QoS setting lets you map each of the eight priority levels to one of seven internal
hardware priority queues.
• DSCP. The six most significant bits of the DiffServ field are called the Differentiated
Services Code Point (DSCP) bits.
6. From the Interface Shaping Rate field, specify the maximum bandwidth allowed. This is
typically used to shape the outbound transmission rate in increments of 64 kbps in this range
of 16–16384. This value is controlled independently of any per-queue maximum bandwidth
configuration. It is effectively a second-level shaping mechanism. The default value is 0. The
value 0 means maximum is unlimited.
The expected shaping at egress interface is calculated as:
frameSize*shaping*64/(frameSize+IFG),where IFG (Inter frame gap) is 20 bytes,
frameSize is configured frame size of the traffic and shaping is configured traffic shaping
in the Interface Shaping Rate field.
For example, when 64 Bytes frame size and 64 Interface Shaping Rate are configured,
expected shaping will be approximately 3121 kbps.
7. Click Cancel to cancel the configuration on the screen and reset the data on the screen to
the latest value of the switch.
8. If you make changes to the page, click Apply to apply the changes to the system.
Interface Queue Configuration
Use the Interface Queue Configuration page to define what a particular queue does by
configuring switch egress queues. User-configurable parameters control the amount of
bandwidth used by the queue, the queue depth during times of congestion, and the
scheduling of packet transmission from the set of all queues on a port. Each port has its own
CoS queue-related configuration.
The configuration process is simplified by allowing each CoS queue parameter to be
configured globally or per-port. A global configuration change is automatically applied to all
ports in the system.