Cisco Catalyst 3550 Series - Queueing and Scheduling

29-11
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 29 Configuring QoS
Understanding QoS
The CoS-to-DSCP, DSCP-to-CoS, and the IP-precedence-to-DSCP map have default values that might
or might not be appropriate for your network.
The default DSCP-to-DSCP-mutation map and the default policed-DSCP map are null maps; they map
an incoming DSCP value to the same DSCP value. The DSCP-to-DSCP-mutation map is the only map
you apply to a specific Gigabit-capable Ethernet port or to a group of 10/100 Ethernet ports. All other
maps apply to the entire switch.
For configuration information, see the “Configuring DSCP Maps” section on page 29-51.
Queueing and Scheduling
After a packet is policed and marked, the queueing and scheduling process begins as described in these
sections:
• Queueing and Scheduling on Gigabit-Capable Ports, page 29-11
• Queueing and Scheduling on 10/100 Ethernet Ports, page 29-15
Queueing and Scheduling on Gigabit-Capable Ports
Figure 29-5 shows the queueing and scheduling flowchart for Gigabit-capable Ethernet ports.