Chapter 24 Configuring ATM Router Module Interfaces

About Rate Limiting

Rate limiting can be applied to individual interfaces. When an interface is configured with this feature, the traffic rate will be monitored by the Ethernet processor interface microcode to verify conformity. Non-conforming traffic is dropped, conforming traffic passes through without any changes.

Features Supported

The following features are supported for rate limiting on the Catalyst 8500 switch router:

This feature is supported on the following interface modules:

Eight-Port 10/100BASE-T Fast Ethernet Interface Modules

16-Port 10/100BASE-T Fast Ethernet Interface Modules

Eight-Port 100BASE-FX Fast Ethernet Interface Modules

16-port 100BASE-FX Fast Ethernet Interface Modules

This feature can be applied on a per-physical-port basis.

This feature is available for input traffic and output traffic.

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.

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.

Configuring Rate Limiting

Enter the following command in interface configuration mode to configure rate limiting on your switch router:

Command

Purpose

 

 

rate-limit {input output} rate burst

Configures rate limiting on an interface.

 

 

For more detailed configuration information, refer to the “Policing and Shaping Overview” section of the Cisco IOS Quality of Service Solutions Configuration Guide.

 

ATM and Layer 3 Switch Router Software Configuration Guide

24-28

OL-1911-05

Page 28
Image 28
Cisco Systems OL-1911-05 Restrictions, Configuring Rate Limiting, Features Supported, Rate-limit input output rate burst