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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 43 Configuring IPv6 Unicast Routing Configuring IPv6
Configuring IPv6 ICMP Rate Limiting
ICMP rate limiting is enabled by default with a default interval between error messages of 100
milliseconds and a bucket size (maximum number of tokens to be stored in a bucket) of 10.
Beginning in privileged EXEC mode, follow these steps to change the ICMP rate-limiting parameters:
To return to the default configuration, use the no ipv6 icmp error-interval global configuration
command.
This example shows how to configure an IPv6 ICMP error message interval of 50 milliseconds and a
bucket size of 20 tokens.
Switch(config)#ipv6 icmp error-interval 50 20
Configuring CEF and dCEF for IPv6
Cisco Express Forwarding (CEF) is a Layer 3 IP switching technology to improve network performance.
CEF implements an advanced IP look-up and forwarding algorithm to deliver maximum Layer 3
switching performance. It is less CPU-intensive than fast-switching route-caching, allowing more CPU
processing power to be dedicated to packet forwarding. In a Catalyst 3750-E switch stack, the hardware
uses distributed CEF (dCEF) in the stack. IPv4 CEF and dCEF are enabled by default. IPv6 CEF and
dCEF are disabled by default, but automatically enabled when you configure IPv6 routing.
To route IPv6 unicast packets, you must first globally configure forwarding of IPv6 unicast packets by
using the ipv6 unicast-routing global configuration command, and you must configure an IPv6 address
and IPv6 processing on an interface by using the ipv6 address interface configuration command.
To disable IPv6 CEF or distributed CEF, use the no ipv6 cef or no ipv6 cef distributed global
configuration command. To reenable IPv6 CEF or dCEF if it has been disabled, use the ipv6 cef or ipv6
cef distributed global configuration command. You can verify the IPv6 state by entering the show ipv6
cef privileged EXEC command.
For more information about configuring CEF and dCEF, see the “Implementing IPv6 Addressing and
Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 ipv6 icmp error-interval interval [bucketsize]Configure the interval and bucket size for IPv6 ICMP error
messages:
• interval—The interval (in milliseconds) between tokens
being added to the bucket. The range is from 0 to
2147483647 milliseconds.
• bucketsize—(Optional) The maximum number of tokens
stored in the bucket. The range is from 1 to 200.
Step 3 end Return to privileged EXEC mode.
Step 4 show ipv6 interface [interface-id] Verify your entries.
Step 5 copy running-config startup-config (Optional) Save your entries in the configuration file.