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Customizing the Display of Recorded Cisco Express Forwarding Events
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Table Of Contents

Customizing the Display of Recorded Cisco Express Forwarding Events

Finding Feature Information

Contents

Prerequisites for Configuring the Display of Recorded Cisco Express Forwarding Events

Restrictions for Configuring the Display of Recorded Cisco Express Forwarding Events

Information About Configuring the Display of Recorded Cisco Express Forwarding Events

Cisco Platform Support for Central Cisco Express Forwarding and Distributed Cisco Express Forwarding

Cisco Express Forwarding Event Log Overview

How to Customize the Display of Recorded Cisco Express Forwarding Events

Customizing Cisco Express Forwarding Event Logging

Displaying Cisco Express Forwarding Event-Log Information

Configuration Examples for Configuring the Display of Recorded Cisco Express Forwarding Events

Customizing Cisco Express Forwarding Event Logging: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Configuring the Display of Recorded Cisco Express Forwarding Events

Glossary


Customizing the Display of Recorded Cisco Express Forwarding Events

First Published: May 2, 2005
Last Updated: February 11, 2008

This module contains information about and instructions for customizing the display of recorded Cisco Express Forwarding events for Cisco IOS releases prior to 12.2(25)S, 12.2(33)SB, 12.2(33)SRA, 12.2.(33)SXH, and 12.4(20)T.

For information about and instructions for customizing the display of recorded Cisco Express Forwarding events for Cisco IOS Releases 12.2(25)S, 12.2(33)SB, 12.2(33)SRA, 12.2.(33)SXH, 12.4(20)T, and later releases, see Customizing the Display of Cisco IOS Event Trace Messages.

You can customize the Cisco Express Forwarding event log display by specifying the size of the Cisco Express Forwarding event log or by choosing to display events by prefix and mask or by Cisco Express Forwarding Virtual Private Network (VPN) routing/forwarding instance (VRF).

Cisco Express Forwarding is an advanced Layer 3 IP switching technology. It optimizes network performance and scalability for all kinds of networks: those that carry small amounts of traffic and those that carry large amounts of traffic in complex patterns, such as the Internet and networks characterized by intensive web-based applications or interactive sessions.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring the Display of Recorded Cisco Express Forwarding Events" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for Configuring the Display of Recorded Cisco Express Forwarding Events2

•Restrictions for Configuring the Display of Recorded Cisco Express Forwarding Events

•Information About Configuring the Display of Recorded Cisco Express Forwarding Events

•How to Customize the Display of Recorded Cisco Express Forwarding Events

•Configuration Examples for Configuring the Display of Recorded Cisco Express Forwarding Events

•Additional References

•Feature Information for Configuring the Display of Recorded Cisco Express Forwarding Events

•Glossary

Prerequisites for Configuring the Display of Recorded Cisco Express Forwarding Events

Cisco Express Forwarding must be running on the networking device before you can customize the display of recorded Cisco Express Forwarding events.

Restrictions for Configuring the Display of Recorded Cisco Express Forwarding Events

If you enable Cisco Express Forwarding and then create an access list that uses the log keyword, the packets that match the access list are not Cisco Express Forwarding switched. They are fast switched. Logging disables Cisco Express Forwarding.

Information About Configuring the Display of Recorded Cisco Express Forwarding Events

Before customizing Cisco Express Forwarding event logging, you should understand the following concepts:

•Cisco Platform Support for Central Cisco Express Forwarding and Distributed Cisco Express Forwarding

•Cisco Express Forwarding Event Log Overview

For links to information about other Cisco Express Forwarding and distributed Cisco Express Forwarding features that you can configure, go to the "Additional References" section.

Cisco Platform Support for Central Cisco Express Forwarding and Distributed Cisco Express Forwarding

Cisco Express Forwarding is enabled by default on most Cisco platforms running Cisco IOS software Release 12.0 or later. When Cisco Express Forwarding is enabled on a router, the Route Processor (RP) performs the express forwarding.

To find out if Cisco Express Forwarding is enabled on your platform, enter the show ip cef command. If Cisco Express Forwarding is enabled, you receive output that looks like this: 

Router# show ip cef 


Prefix              Next Hop            Interface

[...]

10.2.61.8/24        192.168.100.1       FastEthernet1/0/0

                    192.168.101.1       FastEthernet6/1

[...]

If Cisco Express Forwarding is not enabled on your platform, the output for the show ip cef command looks like this: 

Router# show ip cef


%CEF not running

Distributed Cisco Express Forwarding is enabled by default on the Catalyst 6500 series switch, the Cisco 7500 series router, and the Cisco 12000 Series Internet Router. When distributed Cisco Express Forwarding is enabled on your platform, the line cards perform the express forwarding.

If Cisco Express Forwarding is not enabled on your platform, use the ip cef command to enable (central) Cisco Express Forwarding or the ip cef distributed command to enable distributed Cisco Express Forwarding.

Cisco Express Forwarding Event Log Overview

The Cisco Express Forwarding event log collects Cisco Express Forwarding events as they occur, even when debugging is not enabled. This allows the tracing of an event immediately after it occurs. Cisco technical personnel can use the event log to help resolve problems with the Cisco Express Forwarding feature.

When the Cisco Express Forwarding event log has reached its capacity, the oldest event is written over by the newest event. You can use the following commands to change the capacity of the Cisco Express Forwarding event log:

•The ip cef table event-log command allows you to increase or decrease the number of entries that the event log can hold.

•The clear ip cef event-log command allows you to clear all event log entries.

You can use the following commands to display Cisco Express Forwarding events:

•The show ip cef events command displays all recorded Cisco Express Forwarding forwarding information base (FIB) and adjacency events.

•The debug ip cef command and the events keyword record general Cisco Express Forwarding events as they occur.

•The debug ip cef table command enables the real-time collection of events that affect entries in the Cisco Express Forwarding tables.

How to Customize the Display of Recorded Cisco Express Forwarding Events

Perform the following tasks to customize Cisco Express Forwarding event logging and display logging events:

•Customizing Cisco Express Forwarding Event Logging (optional)

•Displaying Cisco Express Forwarding Event-Log Information (optional)

Customizing Cisco Express Forwarding Event Logging

This section contains information about and instructions for customizing Cisco Express Forwarding event logging.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip cef table event-log [size event-number] [match ip-prefix mask] [vrf vrf-name]

4. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip cef table event-log [size event-number] [match ip-prefix mask] [vrf vrf-name]

Example:

Router(config)# ip cef table event-log size 25000

Controls Cisco Express Forwarding table event-log characteristics.

•The size event-number keyword-argument pair specifies the number of event entries. The range is from 1 to 4294967295.

•The match keyword logs events that match the specified prefix and mask.

•The ip-prefix argument is the specified IP prefix to match in dotted decimal format (A.B.C.D).

•The mask argument is the network mask written as A.B.C.D.

•The vrf vrf-name keyword-argument pair displays the named Virtual Private Network (VPN) routing/forwarding instance (VRF) Cisco Express Forwarding table.

Step 4 

exit

Example:

Router(config)# exit

Exits to privileged EXEC mode.

Displaying Cisco Express Forwarding Event-Log Information

Perform the following task to display Cisco Express Forwarding event-log information.

SUMMARY STEPS

1. enable

2. clear ip cef event-log

3. debug ip cef table

4. show ip cef events summary

5. show ip cef events within seconds

6. exit

DETAILED STEPS

Step 1 enable

Use this command to enable privileged EXEC mode. For example: 

Router> enable

Enter your password if prompted.

Step 2 clear ip cef event-log

Use this command to clear the Cisco Express Forwarding event-log buffer. For example:

Router# clear ip cef event-log


Step 3 debug ip cef table

Use this command to enable the collection of events that affect entries in the Cisco Express Forwarding tables. For example: 

Router# debug ip cef table 


01:25:46:CEF-Table:Event up, 10.1.1.1/32 (rdbs:1, flags:1000000) 

01:25:46:CEF-IP:Checking dependencies of 0.0.0.0/0 

01:25:47:CEF-Table:attempting to resolve 10.1.1.1/32 

01:25:47:CEF-IP:resolved 10.1.1.1/32 via 10.9.104.1 to 10.9.104.1 Ethernet2/0/0 

01:26:02:CEF-Table:Event up, default, 0.0.0.0/0 (rdbs:1, flags:400001) 

01:26:02:CEF-IP:Prefix exists - no-op change

Step 4 show ip cef events summary

Use this command to display a summary of recorded Cisco Express Forwarding FIB and adjacency events. For example: 

Router# show ip cef events summary


CEF table events summary:

     Storage for 10000 events (320000 bytes), 822/0 events recorded/ignored

     Matching all events, traceback depth 16

     Last event occurred 00:00:06.516 ago.

Step 5 show ip cef events within seconds

Use this command to display Cisco Express Forwarding events that occurred within (during) a specified number of seconds. For example, within 1 second: 

Router# show ip cef events within 1


CEF table events (storage for 10000 events, 14 events recorded)

+00:00:00.000:[Default-table] *.*.*.*/*           New FIB table          [OK]

+00:00:00.000:[Default-table] 10.1.80.194/32      FIB insert in mtrie    [OK]

+00:00:00.000:[Default-table] 10.1.80.0/32        FIB insert in mtrie    [OK]

+00:00:00.000:[Default-table] 10.1.80.255/32      FIB insert in mtrie    [OK]

+00:00:00.004:[Default-table] 10.1.80.0/24        FIB insert in mtrie    [OK]

+00:00:00.004:[Default-table] 10.1.80.0/24        NBD up                 [OK]

+00:00:00.004:[Default-table] 239.224.0.0/4       FIB insert in mtrie    [OK]

+00:00:00.012:[Default-table] 10.1.80.0/24        NBD up                 [Ignr]

+00:00:00.012:[Default-table] 239.224.0.0/4       FIB remove             [OK]

+00:00:00.016:[Default-table] 239.224.0.0/4       FIB insert in mtrie    [OK]

+00:00:05.012:[Default-table] 239.224.0.0/4       FIB remove             [OK]

+00:00:05.012:[Default-table] 239.224.0.0/4       FIB insert in mtrie    [OK]

+00:00:28.440:[Default-table] 239.224.0.0/4       FIB remove             [OK]

+00:00:28.440:[Default-table] 239.224.0.0/4       FIB insert in mtrie    [OK]

First event occured at 00:00:36.568 (00:04:40.756 ago)

Last event occured at 00:01:05.008 (00:04:12.316 ago)

Step 6 exit

Use this command to exit to user EXEC mode. For example: 

Router# exit

Router>

Configuration Examples for Configuring the Display of Recorded Cisco Express Forwarding Events

This section contains one configuration example for customizing the display of recorded Cisco Express Forwarding events:

•Customizing Cisco Express Forwarding Event Logging: Example

Customizing Cisco Express Forwarding Event Logging: Example

The following example shows how to enable event logging for Cisco Express Forwarding: 

clear ip cef event-log

!

debug ip cef table

!

configure terminal

!

ip cef table event-log size 25000

exit

!

In this example, the Cisco Express Forwarding event log is configured to hold 25000 entries.

Additional References

The following sections provide references related to the customizing of the display of recorded Cisco Express Forwarding events.

Related Documents

Related Topic
Document Title

Cisco Express Forwarding commands

Cisco IOS IP Switching Command Reference

List of the features documented in the Cisco Express Forwarding modules

Cisco Express Forwarding Features Roadmap

Overview of the Cisco Express Forwarding feature

Cisco Express Forwarding Overview

Tasks for verifying basic Cisco Express Forwarding and distributed Cisco Express Forwarding operation

Configuring Basic Cisco Express Forwarding for Improved Performance, Scalability, and Resiliency in Dynamic Networks

Tasks for enabling or disabling Cisco Express Forwarding or distributed Cisco Express Forwarding

Enabling or Disabling Cisco Express Forwarding or Distributed Cisco Express Forwarding to Customize Switching and Forwarding for Dynamic Networks

Tasks for configuring load-balancing schemes for Cisco Express Forwarding

Configuring a Load-Balancing Scheme for Cisco Express Forwarding Traffic

Tasks for configuring Cisco Express Forwarding consistency checkers

Configuring Cisco Express Forwarding Consistency Checkers for Route Processors and Line Cards

Tasks for configuring epochs for Cisco Express Forwarding tables

Configuring Epochs to Clear and Rebuild Cisco Express Forwarding and Adjacency Tables

Tasks for configuring and verifying Cisco Express Forwarding network accounting

Configuring Cisco Express Forwarding Network Accounting

Tasks for customizing the display of recorded Cisco Express Forwarding events trace messages for Cisco  IOS Releases 12.2(25)S, 12.2(33)SB, 12.2(33)SRA, 12.2.(33)SXH, 12.4(20)T and later releases

Customizing the Display of Cisco IOS Event Trace Messages

Causes of common Cisco Express Forwarding-related error messages on platforms running distributed Cisco Express Forwarding switching (Cisco 7500 series routers and Cisco 12000 series Internet routers) and how to troubleshoot them

Troubleshooting Cisco Express Forwarding-Related Error Messages


Standards

Standards
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—


MIBs

MIBs
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFCs
Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

—


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for Configuring the Display of Recorded Cisco Express Forwarding Events

Table 1 lists the features in this module and provides links to specific configuration information. Only features that were introduced or modified in Cisco IOS Release 12.2(1) or a later release appear in the table.

For information on a feature in this technology that is not documented here, see the Cisco Express Forwarding Features Roadmap.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.

Table 1 Feature Information for Configuring the Display of Recorded Cisco Express Forwarding Events 

Feature Name
Releases
Feature Configuration Information

This table is intentionally left blank because no features were introduced or modified in Cisco IOS Release 12.2(1) or later. This table will be updated when feature information is added to this module.

—

—


Glossary

adjacency—A relationship formed between selected neighboring routers and end nodes for the purpose of exchanging routing information. Adjacency is based upon the use of a common media segment by the routers and nodes involved.

Cisco Express Forwarding—A Layer 3 switching technology. Cisco Express Forwarding can also refer to central Cisco Express Forwarding mode, one of two modes of Cisco Express Forwarding operation. Cisco Express Forwarding enables a Route Processor to perform express forwarding. Distributed Cisco Express Forwarding is the other mode of Cisco Express Forwarding operation.

distributed Cisco Express Forwarding—A mode of Cisco Express Forwarding operation in which line cards (such as Versatile Interface Processor (VIP) line cards) maintain identical copies of the forwarding information base (FIB) and adjacency tables. The line cards perform the express forwarding between port adapters; this relieves the Route Switch Processor of involvement in the switching operation.

FIB—forwarding information base. A component of Cisco Express Forwarding that is conceptually similar to a routing table or information base. The router uses the FIB lookup table to make destination-based switching decisions during Cisco Express Forwarding operation. The router maintains a mirror image of the forwarding information in an IP routing table.

line card—A general term for an interface processor that can be used in various Cisco products. For example, a Versatile Interface Processor (VIP) is a line card for the Cisco 7500 series router.

prefix—The network address portion of an IP address. A prefix is specified by a network and mask and is generally represented in the format network/mask. The mask indicates which bits are the network bits. For example, 1.0.0.0/16 means that the first 16 bits of the IP address are masked, making them the network bits. The remaining bits are the host bits. In this example, the network number is 10.0.

VPN—Virtual Private Network. The result of a router configuration that enables IP traffic to use tunneling to travel securely over a public TCP/IP network.

VRF—A Virtual Private Network (VPN) routing/forwarding instance. A VRF consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine what goes into the forwarding table. In general, a VRF includes the routing information that defines a customer VPN site that is attached to a PE router.

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