- CEF Overview
- Configuring Basic Cisco Express Forwarding
- Enabling or Disabling CEF or dCEF
- Configuring a Load-Balancing Scheme
- Configuring Epochs
- Configuring CEF Consistency Checkers
- Configuring CEF Network Accounting
- Customizing the Display of Recorded CEF Events
- Customizing the Display of CEF Event Trace Messages
- SNMP CEF-MIB Support
- Cisco Express Forwarding Command Changes
- CEF Enhancements
- IPv6 CEF-Switched Tunnels
Contents
- Customizing the Display of Recorded CEF Events
- Finding Feature Information
- Prerequisites for the Display of Recorded CEF Events
- Restrictions for the Display of Recorded CEF Events
- Information About the Display of Recorded CEF Events
- Cisco Platform Support for Central CEF and dCEF
- CEF Event Log Overview
- How to Customize the Display of Recorded CEF Events
- Customizing CEF Event Logging
- Displaying CEF Event-Log Information
- Configuration Examples for the Display of Recorded CEF Events
- Example Customizing CEF Event Logging
- Additional References
- Feature Information for the Display of Recorded CEF Events
- Glossary
Customizing the Display of Recorded CEF Events
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
- Prerequisites for the Display of Recorded CEF Events
- Restrictions for the Display of Recorded CEF Events
- Information About the Display of Recorded CEF Events
- How to Customize the Display of Recorded CEF Events
- Configuration Examples for the Display of Recorded CEF Events
- Additional References
- Feature Information for the Display of Recorded CEF Events
- Glossary
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for the Display of Recorded CEF 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 the Display of Recorded CEF 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 the Display of Recorded CEF Events
For links to information about other Cisco Express Forwarding and distributed Cisco Express Forwarding features that you can configure, go to the Additional References.
Cisco Platform Support for Central CEF and dCEF
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 cefcommand. 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 cefcommand 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.
CEF 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-logcommand 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 eventscommand 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 tablecommand enables the real-time collection of events that affect entries in the Cisco Express Forwarding tables.
How to Customize the Display of Recorded CEF Events
Customizing CEF Event Logging
This section contains information about and instructions for customizing Cisco Express Forwarding event logging.
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
Displaying CEF Event-Log Information
Perform the following task to display Cisco Express Forwarding event-log information.
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: 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
Example: |
| 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: 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: 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: Example: 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: Example: Router# exit Router> |
Configuration Examples for the Display of Recorded CEF Events
Example Customizing CEF Event Logging
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
Related Documents
|
Related Topic |
Document Title |
|---|---|
|
Cisco IOS commands |
|
|
Cisco Express Forwarding commands |
Cisco IOS IP Switching Command Reference |
|
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: |
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 and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for the Display of Recorded CEF Events
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.|
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 Forwardin g--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.