Cisco ATM and Layer 3 Switch Router OL-1911-05 - Manual (Page 28)

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ATM and Layer 3 Switch Router Software Configuration Guide
OL-1911-05
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:
For more detailed configuration information, refer to the “Policing and Shaping Overview” section of
the Cisco IOS Quality of Service Solutions Configuration Guide.
Command Purpose
rate-limit {input | output} rate burst Configures rate limiting on an interface.