QoS Configurations on Catalyst Switches 731
Example 10-23 Committing a QoS ACL to the ASIC
Cat65k> (enable) commit qos acl IP-PHONES
QoS ACL 'IP_PHONES' successfully committed.
Cat65k> (enable)
After the QoS ACL has been committed to hardware, you can map it to the desired VLAN. This allows the 63xx 10/100 line cards to get around the trust state issue. The set qos acl map command enables you to accomplish this task. Example 10-24 demonstrates the configuration of a QoS ACL map.
Example 10-24 Mapping the QoS ACL to a VLAN
Cat65k> (enable) set qos acl map IP_PHONES 110
ACL IP_PHONES is successfully mapped to vlan 110.
Cat65k> (enable)
Connecting a Catalyst OS Switch to WAN Segments
In Figure 10-11, a WAN router is connected to port 6/1. Typically, you will trust the Layer 3 markings from a WAN device. To configure QoS for a port that connects the distribution layer switch to a WAN segment, use port-based QoS with a trust state of trust-ipprec, as shown in Example 10-25.
Example 10-25 Associating QoS with Port 6/1 and Enabling IP Precedence Trust State
cat6k-distrib> (enable) set port qos 6/1 port-based
cat6k-distrib> (enable) set port qos 6/1 trust trust-ipprec
Trust type trust-ipprec not supported on port(s) 6/1
Receive thresholds enabled on ports(s) 6/1
Trust type set to untrusted on port(s) 6/1As discussed in the “Configuring Trust Boundaries” section, with all 63xx series 10/100 Ethernet line cards with 1q4t ports, the trust-ipprec port keyword displays an error message stating that trust-ipprec is not supported. This configuration must be entered to activate the receive queue drop thresholds; however, the trust state of the ports remains untrusted. You must configure a trust-ipprec ACL to match the ingress traffic to successfully apply the trust-ipprec trust state. The 65xx series 10/100 Ethernet line cards do not have this issue.
734 Chapter 10: LAN QoS
this example, any frame that arrives with a CoS value of 3, 4, or 5 is placed in Queue 2, threshold 1. This matches the configuration from the “CoS-to-Egress Queue Mapping” section.
The show qos statistics l3stats command shows a summary of all IP packets that have had their CoS/ToS fields modified by the Layer 3 switching engine as well as any packet drops resulting from policing, as shown in Example 10-29.
Example 10-29 Show QoS Layer 3 Statistics
CatOS> (enable) show qos statistics l3stats
Packets dropped |
due |
to policing: |
0 |
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IP |
packets with |
ToS |
changed: |
10473 |
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IP |
packets with |
CoS |
changed: |
4871 |
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Non-IP |
packets with CoS changed: |
0 |
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CatOS> |
(enable) |
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The show qos statistics command displays detailed information about the number of packets that have been dropped from each queue and threshold. In Example 10-30, all packets dropped are in the first drop threshold of TX Queue 1.
Example 10-30 The show qos statistics Command
CatOS> (enable) show qos statistics 2/1
Tx port type of port 2/1 : 2q2t
Q # Threshold #:Packets dropped
--- -----------------------------------------------
1 1:393210 pkts, 2:0 pkts
21:0 pkts, 2:0 pkts
Rx port type of port 2/1 : 1q4t
Q # |
Threshold #:Packets |
dropped |
--- |
----------------------------------------------- |
|
1 |
1:0 pkts, 2:0 pkts, |
3:0 pkts, 4:0 pkts |
CatOS> (enable)
The show qos map runtime command enables you to display the CoS/DSCP/IP precedence mappings within the Catalyst 6500. You can now display the mappings configured in the “Layer 2-to-Layer 3 Mapping” section of this chapter.
Example 10-31 show the CoS value of 3 is mapped to the DSCP decimal value of 26 (AF31), whereas the CoS value of 5 is mapped to the DSCP decimal value of 46 (EF).
736 Chapter 10: LAN QoS
Example 10-33 The show qos map runtime ipprec-dscp-map Command (Continued)
326 -> 26 = AF31
432
546 -> 46 = EF
6 48
756
Cat65k-Access> (enable)
Configuration of a Catalyst Switch Using IOS
This section explores the configuration of a Catalyst IOS switch in the access and distribution layers. Assume that your IP telephony network is configured as depicted in Figure 10-12.
Figure 10-12 Catalyst IOS Switch
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802.1q Trunk |
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IP Phone |
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VLAN 110 |
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CallManager 2 |
Catalyst OS Switch |
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In this example, CallManager 1 is connected to port 1, CallManager 2 is connected to port 2, and 10 IP Phones are connected to ports 11 through 20 respectively. Each IP Phone has a PC attached to the IP Phone switch port. And an IP video server is also connected to port 10.
The Catalyst 6500, 4500 with the Supervisor III or IV Engine, 3550, and 3524 are examples of Catalyst IOS switches. The QoS required to minimize delay, jitter, and packet drops for these switches can be broken down into the following tasks:
• Configuring voice VLANs for a Catalyst IOS switch