Cisco Systems OL-7396-01 Manual De Usuario
24-2
ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter 24
Configuring Rate Limiting and Traffic Shaping
Traffic Shaping
Restrictions
Restrictions for rate limiting on the Catalyst 8500 switch router include the following:
•
This feature is not supported on the LightStream 1010.
•
IPX and rate limiting cannot be configured at the same time. If rate limiting is configured on an
interface, IPX will be automatically disabled on that interface. In addition, IPX will be automatically
disabled on any of the three other interfaces which are controlled by the same hardware
micro-controller as the configured interface. For example, if rate limiting is configured on Fast
Ethernet slot 0, IPX will not work on slots 0, 1, 2, and 3.
interface, IPX will be automatically disabled on that interface. In addition, IPX will be automatically
disabled on any of the three other interfaces which are controlled by the same hardware
micro-controller as the configured interface. For example, if rate limiting is configured on Fast
Ethernet slot 0, IPX will not work on slots 0, 1, 2, and 3.
•
The QoS mapping ratio might be disrupted by the rate limiting configuration.
•
Due to additional processing, when rate limiting is enabled, switching might not be at wire speed.
Note
Broadcast packets, dropped ACL packets, packets dropped due to expiration of the designed Time To
Live, and bad CRC packets are included in the rate limit calculation. This might cause a problem if the
policed port is not part of a point-to-point connection and is connected via a hub rather than a layer 2
switch.
Live, and bad CRC packets are included in the rate limit calculation. This might cause a problem if the
policed port is not part of a point-to-point connection and is connected via a hub rather than a layer 2
switch.
Configuring Rate Limiting
Enter the following command in interface configuration mode to configure rate limiting on your switch
router:
router:
For more detailed configuration information, refer to the “Policing and Shaping Overview” section of
the Cisco IOS Quality of Service Solutions Configuration Guide.
the Cisco IOS Quality of Service Solutions Configuration Guide.
Example
The following is an example of how to configure rate limiting on your switch router:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z
Router(config)# interface f0/0/0
Router(config-if)# rate-limit input 1000000 20000
Router(config-if)# rate-limit output 100000 30000
Router(config-if)# exit
Traffic Shaping
Traffic shaping allows you to shape output traffic (egress traffic) on a per-physical port basis. Ucode
monitors output traffic to verify that it conforms to the rate configured on the switch router. When excess
traffic comes into the switch, the output side of the processor interface applies back pressure and queues
the excess traffic in the switch fabric. If the switch fabric queues overflow, the traffic is dropped. This
feature is similar to the IOS GTS feature.
monitors output traffic to verify that it conforms to the rate configured on the switch router. When excess
traffic comes into the switch, the output side of the processor interface applies back pressure and queues
the excess traffic in the switch fabric. If the switch fabric queues overflow, the traffic is dropped. This
feature is similar to the IOS GTS feature.
Command
Purpose
rate-limit {input | output} rate burst
Configures rate limiting on an interface.