QoS and QoS Policies
30
Quality of Service Guide
3HE 11014 AAAC TQZZA Edition: 01
3.1.4 Scheduling Modes
The scheduler modes available on adapter cards are profiled (2-priority), 4-priority,
and 16-priority. Which modes are supported on a particular adapter card depends on
whether the adapter card is a first-, second-, or third-generation card.
On Gen-3 hardware, 4-priority scheduling mode is the implicit, default scheduling
mode and is not user-configurable. Gen-3 platforms with a TDM block support
4-priority scheduling mode. Gen-2 adapter cards support 16-priority and 4-priority
scheduling modes. Gen-1 adapter cards support profile (2-priority) and 4-priority
scheduling modes.
For details on differences between Gen-1, Gen-2, and Gen-3 hardware related to
scheduling mode QoS behavior, see QoS for Gen-3 Adapter Cards and Platforms.
For information on scheduling modes as they apply to traffic direction, refer to the
following sections:
• Access Ingress Queuing and Scheduling
• Network Egress Scheduling
• Network Ingress Scheduling
• Access Egress Queuing and Scheduling
3.1.5 Intelligent Discards
Most 7705 SAR systems are susceptible to network processor congestion if the
packet rate of small packets received on a node or card exceeds the processing
capacity. If a node or card receives a high rate of small packet traffic, the node or
card enters overload mode. Prior to the introduction of intelligent discards, when a
node or card entered an overload state, the network processor would randomly drop
packets.
The “intelligent discards during overload” feature allows the network processor to
discard packets according to a preset priority order. In the egress direction, intelligent
discards is applied to traffic entering the card from the fabric.
Note: Throughout the 7705 SAR documentation set, first-, second-, and third-generation
Ethernet adapter cards and Ethernet ports on fixed platforms are also referred to as Gen-1,
Gen-2, and Gen-3 hardware.
To Next Page
Loading...
