Queueing And Scheduling On Ingress Queues - Cisco Catalyst 3120 Software Manual

Chapter 36 Configuring QoS

Queueing and Scheduling on Ingress Queues

Figure
Figure 36-8
(DSCP or CoS value).
Determine ingress queue
number, buffer allocation,
and WTD thresholds.
Queue the packet. Service
the queue according to
Note SRR services the priority queue for its configured share before servicing the other queue.
The switch supports two configurable ingress queues, which are serviced by SRR in shared mode only.
Table 36-1
Table 36-1
Queue Type
Normal
Expedite
1. The switch uses two nonconfigurable queues for traffic that is essential for proper network and stack operation.
OL-12247-01
36-8shows the queueing and scheduling flowchart for ingress ports.
Queueing and Scheduling Flowchart for Ingress Ports
Start
Read QoS label
Yes
Are thresholds
being exceeded?
No
the SRR weights.
Send packet to
the stack ring.
describes the queues.
Ingress Queue Types
1
Function
User traffic that is considered to be normal priority. You can configure three different
thresholds to differentiate among the flows. You can use the mls qos srr-queue input
threshold, the mls qos srr-queue input dscp-map, and the mls qos srr-queue input
cos-map global configuration commands.
High-priority user traffic such as differentiated services (DF) expedited forwarding or
voice traffic. You can configure the bandwidth required for this traffic as a percentage
of the total traffic or total stack traffic by using the mls qos srr-queue input
priority-queue global configuration command. The expedite queue has guaranteed
bandwidth.
Drop packet.
Cisco Catalyst Blade Switch 3120 for HP Software Configuration Guide
Understanding QoS
36-15