Cisco IOS Dial Technologies Configuration Guide, Release 12.4T
CEF Support for Dialer Profiles on Cisco 7500 Routers
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CEF Support for Dialer Profiles on Cisco 7500 Routers

Table Of Contents

CEF Support for Dialer Profiles on Cisco 7500 Routers

Contents

Restrictions for Asynchronous Line Monitoring feature

Information About Asynchronous Line Monitoring feature

CEF Switching Across Dialer Interfaces

How to Implement Dialer CEF Support on Cisco 7500 Routers with RSP

Verifying that Asynchronous Line Monitoring feature Feature Is Operational

Configuration Examples for Asynchronous Line Monitoring feature

Recording CEF Events for Dialer Interface: Example

Displaying CEF Adjacency Table for Dialer Interface: Example

Displaying CEF Switching Status on IP Dialer Interface: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference


CEF Support for Dialer Profiles on Cisco 7500 Routers


The CEF Support for Dialer Profiles on Cisco 7500 Routers feature adds support for Cisco Express Forwarding (CEF) switching on dialer profile interfaces, on Cisco 7500 routers with the Route Switch Processor (RSP).

Release
Modification

12.2(4)T

This feature was introduced.

12.3(4)T

Support for this feature was added for dialer profile interfaces on Cisco 7500 routers with an RSP.


Feature History for the CEF Support for Dialer Profiles on Cisco 7500 Routers Feature

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

Restrictions for Asynchronous Line Monitoring feature

Information About Asynchronous Line Monitoring feature

How to Implement Dialer CEF Support on Cisco 7500 Routers with RSP

Configuration Examples for Asynchronous Line Monitoring feature

Additional References

Command Reference

Restrictions for Asynchronous Line Monitoring feature

The Asynchronous Line Monitoring feature feature does not support distributed CEF (dCEF) switching on dialer profile interfaces.

Information About Asynchronous Line Monitoring feature

To use the Asynchronous Line Monitoring feature feature, you need to understand the following concept:

CEF Switching Across Dialer Interfaces

CEF Switching Across Dialer Interfaces

The Asynchronous Line Monitoring feature feature introduced in Cisco IOS Release 12.3(4)T adds support for CEF switching across dialer interfaces on Cisco 7500 routers with an RSP.

CEF switching on dialer profile interfaces allows packets to be CEF switched across the interface, rather than fast switched or process switched. CEF switching avoids the overhead of continuous cache cycles by using a Forwarding Information Base (FIB) to make the destination switching decision. The FIB mirrors the contents of the IP routing table, that is, there is a one-to-one correspondence between FIB table entries and routing table prefixes and, therefore, no need to maintain a separate route cache.

This FIB provides significant benefits in terms of performance, scalability, network resilience, and functionality, particularly in large complex networks with dynamic traffic patterns. CEF switching is less CPU-intensive than fast switched route caching. More CPU processing power can be dedicated to Layer 3 services such as quality of service (QoS) and encryption.

CEF switching also offers an unprecedented level of switching consistency and stability in large dynamic networks. In dynamic networks, fast-switched cache entries are frequently invalidated due to routing changes. These changes can cause traffic to be process switched using the FIB routing table, rather than fast switched using the route cache. Because the FIB lookup table contains all known routes that exist in the routing table, it eliminates route cache maintenance and the fast-switch or process-switch forwarding scenario. CEF can switch traffic more efficiently than typical demand caching schemes.

How to Implement Dialer CEF Support on Cisco 7500 Routers with RSP

You need perform no configuration tasks to use the CEF support for dialer interfaces configured on a Cisco 7500 with the RSP; the dialer CEF switching functionality is inherent in the Cisco IOS Release 12.3(4)T software.

The Asynchronous Line Monitoring feature feature has been tested successfully with dialer interface functionality including dialer profiles, legacy dial-on-demand routing (DDR), and large-scale dial-out Multiprotocol Label Switching Virtual Private Network (MPLS VPN).

The following section provides an optional task to verify that dialer CEF is enabled:

Verifying that Asynchronous Line Monitoring feature Feature Is Operational

Verifying that Asynchronous Line Monitoring feature Feature Is Operational

Perform the following task to verify that the Asynchronous Line Monitoring feature feature is operational.

SUMMARY STEPS

1. enable

2. debug ip cef {drops [rpf [access-list]] [access-list] | receive [access-list] | events [access-list] | interface | dialer}

3. show adjacency [type number] [detail] [summary] [internal]

4. show ip interface [type number]

5. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

debug ip cef {drops [rpf [access-list]] [access-list] | receive [access-list] | events [access-list] | interface | dialer}

Example:

Router# debug ip cef dialer

Records various CEF events.

dialer—Records IP CEF events for dialer interfaces.

Step 3 

show adjacency [type number] [detail] [summary] [internal]

Example:

Router# show adjacency dialer1 internal

Displays an adjacency, if it exists, for a connected device, and whether the adjacency is valid.

internal—Displays CEF adjacency table dialer interface information.

Step 4 

show ip interface [type number]

Example:

Router# show ip interface dialer1

Displays the usability status of IP interfaces, and will display whether CEF is enabled and the CEF switching vector is set.

Step 5 

exit

Example:

Router> exit

Exits privileged EXEC mode.

Configuration Examples for Asynchronous Line Monitoring feature

This section provides the following examples for the Asynchronous Line Monitoring feature feature:

Recording CEF Events for Dialer Interface: Example

Displaying CEF Adjacency Table for Dialer Interface: Example

Displaying CEF Switching Status on IP Dialer Interface: Example

Recording CEF Events for Dialer Interface: Example

The following is a sample record of dialer CEF events on a dialer interface reported by the debug ip cef dialer command:

Router# debug ip cef dialer

00:31:44:CEF-Dialer (profile dynamic encap (not MLP)):add link to 10.10.10.2 via Dialer1 
through Dialer1
00:31:44:CEF-Dialer:adjacency added:0x81164850
00:31:44:CEF-Dialer:adjacency found:0x81164850; fib->count:1

Displaying CEF Adjacency Table for Dialer Interface: Example

The following is sample output from the show adjacency dialer1 internal command for a dialer profile that indicates where adjacency for the dialer interface is updated:

Router# show adjacency dialer1 internal

Protocol Interface                 Address
IP       Dialer1                   point2point(9)
                                   22 packets, 2288 bytes
                                   FF030021
                                   CEF   expires:00:01:01
                                         refresh:00:00:13
                                   Fast adjacency disabled
                                   IP redirect enabled
                                   IP mtu 1500 (0x0)
                                   Fixup disabled
                                   Adjacency pointer 0x826B1F10, refCount 9
                                   Connection Id 0x0     
                                   Bucket 14

Displaying CEF Switching Status on IP Dialer Interface: Example

The following is sample output from the show ip interface dialer1 command. Reports about CEF switching on the dialer interface are shown in bold text, for purpose of example.

Router# show ip interface dialer1

Dialer1 is up, line protocol is up
  Internet address is 10.10.10.1/24
  Broadcast address is 255.255.255.255
  Address determined by setup command
  MTU is 1500 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are always sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is enabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF Fast switching turbo vector
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF

Additional References

The following sections provide references related to the Asynchronous Line Monitoring feature feature.

Related Documents

Related Topic
Document Title

Cisco Express Forwarding

Cisco IOS IP Switching Configuration Guide; refer to the Cisco Express Forwarding chapters in "Part 1: Cisco IOS Switching Paths"

Cisco IOS IP Switching Command Reference

Dialer interfaces and profiles; Dialer CEF

Cisco IOS Dial Technologies Configuration Guide; refer to the chapters "Configuring Peer-to-Peer DDR with Dialer Profiles" and "Dialer CEF".

Cisco IOS Dial Technologies Command Reference


Standards

Standards
Title

None


MIBs

MIBs
MIBs Link

None

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

None


Technical Assistance

Description
Link

Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/public/support/tac/home.shtml


Command Reference

This feature uses no new or modified commands. For information about commands used with this feature, see the Cisco IOS Dial Technologies Command Reference at http://www.cisco.com/en/US/docs/ios/dial/command/reference/dia_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.