3-29
Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
956467
Chapter 3 QoS in an AVVID-Enabled Campus Network
Selecting an Access-Layer Switch
Port RxMacFifoOverrun RxMacFifoUnderrun RxCdmFifoOverrun TxCsmFifoUnderrun
Gi3/2 0 0 0 0
Port NoPBA/CdmFifoOverun
Gi3/2 0
Catalyst 4000 with Supervisor II
shows a general model for the Catalyst 4000 with Supervisor II as an access device (as
illustrated in the QoS configurations discussed in this chapter).
Figure 3-9
General Model for Catalyst 4000 with Supervisor II QoS Configurations
This section presents suggested configurations for port scheduling and queuing on the Catalyst 4000
with Supervisor II. In general:
·
The recommended configuration for the receive interface is 1Q-FIFO--one standard FIFO queue.
·
The recommended configuration for the transmit interface is 2Q1T--two standard queues with a
single threshold. Scheduling is on a round-robin basis. Admission to the queues is based on 802.1p
CoS value and is user configurable in pairs. If you enable QoS but do not modify the
CoS-to-transmit queue mappings, switch performance could be affected because all traffic is
assigned to queue 1. Once QoS is enabled on the Catalyst 4000, you must change the CoS mappings
to use the newly created queue.
·
The default queue admission criteria for the Catalyst 4000 is: CoS 0 through 7 goes to queue 1, all
other (broadcast, multicast, and unknown) traffic goes to queue 2.
Si
Si
Si
IP
VVID=111
VLAN=11
Core
Distribution
Access
Catalyst
6500
Catalyst 4000
74700