Owner's Manual

Chapter 15. QoS | 371
NETGEAR 8800 User Manual
When multiple QoS profiles are contending for port bandwidth and the egress traffic in each
profile is within profile, the scheduler determines how the QoS profiles are serviced as
described in
Scheduling on page 368. In strict-priority mode, the queues are serviced based
on the queue service priority value. In weighted fair-queuing mode, the queues are serviced
based on the configured weight.
When configured to do so, the priority of a QoS profile can determine the 802.1p bits used in
the priority field of a forwarded frame (see
Replacing 802.1p Priority Information on Egress
on page 374). The priority of a QoS profile can determine the DiffServ code point value used
in an IP packet when the packet is forwarded (see Replacing a DSCP on Egress on
page 375).
A QoS profile change does not alter the behavior of the switch until it is assigned to a traffic
group.
Multicast Traffic Queues
BlackDiamond 20800 series switches provide four traffic queues for single-rate rate-limiting
of multicast traffic. The CoS 802.1p value in an ingress multicast packet selects the multicast
traffic queue. CoS 802.1p value 3 selects the guaranteed delivery traffic queue. CoS 802.1p
values 0 to 2 select one of the three best-effort delivery traffic queues.
To apply ingress rate-limiting to a multicast traffic queue, configure a single rate meter and
apply it to either the multicast-guaranteed traffic queue or the best-effort traffic queue. When
you apply a meter to the best-effort traffic queue, it applies to all three best-effort multicast
traffic queues.
Egress Port Rate Limiting and Rate Shaping
Egress port rate limiting and rate shaping allow you to define limits for all egress traffic
coming from the egress QoS profiles and traffic queues. On NETGEAR 8800 switches, you
can apply single-rate rate-limiting. You can also configure ports to pass an unlimited flow as
describe in
Disabling Rate Limiting and Rate Shaping on page 368.
Configuring QoS
The following sections provide information on configuring QoS:
• Platform Configuration Procedures on page 372
• Selecting the QoS Scheduling Method on page 373
• Configuring 802.1p or DSCP Replacement on page 374
• Configuring Egress QoS Profile Rate Shaping on page 378
• Configuring Egress Port Rate Limits on page 379
• Configuring Traffic Groups on page 380
• Creating and Managing Meters on page 383
• Adjusting the Byte Count Used to Calculate Traffic Rates on page 384