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FPG:Endpoint Agnostic Port Allocation---

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FPG: Endpoint Agnostic Port Allocation

Finding Feature Information

Contents

Information About Endpoint Agnostic Port Allocation

How to Configure Endpoint Agnostic Port Allocation

Configuring Endpoint Agnostic Port Allocation

Restrictions

Verifying Endpoint Agnostic Port Support

Configuration Examples for Endpoint Agnostic Port Allocation

Configuring Endpoint Allocation: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Feature Information for Endpoint Agnostic Port Allocation


FPG: Endpoint Agnostic Port Allocation

First Published: February 27, 2009
Last Updated: February 27, 2009

When the Endpoint Agnostic Port Allocation feature is configured, an entry is added to the Symmetric Port Database. If the entry is already available, the port listed in the Symmetric Port Database is used and the packet is sent. This feature is only required if you need to configure NAT with pool overload or interface overload. Endpoint Agnostic Port Allocation is also known as Symmetric Port Allocation.

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 Endpoint Agnostic Port Allocation" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS, Catalyst OS, and Cisco IOS XE 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

•Information About Endpoint Agnostic Port Allocation

•How to Configure Endpoint Agnostic Port Allocation

•Configuration Examples for Endpoint Agnostic Port Allocation

•Additional References

•Command Reference

•Feature Information for Endpoint Agnostic Port Allocation

Information About Endpoint Agnostic Port Allocation

When a packet is being transmitted, the Symmetric Port Database is checked to see if the requested port is already allocated. If it has been allocated, it is checked if the source computer entry in the database matches the computer requesting the port. If this is true, the port listed in the Symmetric Port Database is used and the packet is sent.

If the computers do not match or if the requested port is not in the Symmetric Port Database, the feature continues checks to the NAT Port database for an entry matching the requested port. If no entry is found, this means that the port is available. A new entry is added to the NAT Port database, and to the existing NAT database, allocating the port to the requesting computer, and the packet is sent.

If no matching entry in the NAT Port database is found, it means that the port is busy, or otherwise unavailable. The next available port is found, which is allocated to the requesting computer. An entry is added to the NAT Port database with the requesting computer and the available port. An entry is added to the Symmetric Port database, with the requesting computer, the allocated port and the requested port and the packet is sent.

This feature is only required if you need to configure NAT with pool overload or interface overload. This feature is not applicable for other NAT configurations.

How to Configure Endpoint Agnostic Port Allocation

This section contains the following procedures:

•Configuring Endpoint Agnostic Port Allocation

•Verifying Endpoint Agnostic Port Support

Configuring Endpoint Agnostic Port Allocation

Perform this task to configure NAT to support the Endpoint Agnostic Port Allocation feature.

Restrictions

This feature must be enabled by the user. It should be enabled before NAT is enabled. If it is enabled later, it will not translate the previously established connection. When this feature is disabled, it will not be seen in the output of the show running-config command.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface interfacename

4. ip nat inside

5. exit

6. access list 1 permit ip address mask

7. ip nat inside source list 1 interface name

8. ip nat service enable-sym-port

9. 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 

interface interface name

Example:

Router (config)# interface Ethernet 0/0

Configures the Ethernet 0/0 interface.

Step 4 

ip nat inside


Example:

Router (config-if)# ip nat inside

Enables Network Address Translation (NAT) for the inside address.

Step 5 

exit


Example:

Router (config-if)# exit

Exits interface configuration mode.

Step 6 

access list 1 permit ip address mask


Example:

Router (config)# access list 1 permit 172.18.192.0.0.0.0.255

Creates an access list called 1.

Step 7 

ip nat inside source list 1 interface interface name

Example:

Router (config)# ip nat inside source list 1 interface Ethernet 0/0

Enables NAT for the inside source for access list 1 which is attached to the Ethernet interface.

Step 8 

ip nat service enable-sym-port


Example:

Router (config)# ip nat service enable-sym-port

Enables the symmetric port allocation.

Step 9 

exit


Router(config)# exit

Exits global configuration mode.

Verifying Endpoint Agnostic Port Support

To verify the Endpoint Agnostic Port Support feature, use the following command.

SUMMARY STEPS

1. show ip nat translations

DETAILED STEPS

Step 1 show ip nat translations 

Router# show ip nat translations 


NAT Symmetric Port Database: 1 entries 
public ipaddr:port [tableid] | port# [refcount][syscount] | localaddr:localport [flags] 
172.18.192.69:1024 [0] | 1025 [1] [0] | 172.18.192.69:1024 [0]

:


Configuration Examples for Endpoint Agnostic Port Allocation

This section provides the following configuration example

•Configuring Endpoint Allocation: Example

Configuring Endpoint Allocation: Example 

interface Ethernet0/0

	ip nat inside

	exit

access list 1 permit 172.18.192.0.0.0.255

ip nat inside source list 1 interface Ethernet0/0

ip nat service enable-sym-port

end

Additional References

The following sections provide references related to the Endpoint Agnostic feature.

Related Documents

Related Topic
Document Title

NAT configuration tasks

"Configuring NAT for IP Address Conservation" module

NAT maintenance

"Monitoring and Maintaining NAT" module

NAT commands: complete command syntax, command mode, command history, usage guidelines, and examples

Cisco IOS IP Addressing Services Command Reference


Standards

Standard
Title

No new or modified standards are supported by this

feature, and support for existing standards has not been

modified by this feature.

_


MIBs

MIB
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

RFC
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


Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS IP Addressing Command Reference at http://www.cisco.com/en/US/docs/ios/ipaddr/command/reference/
ipaddr_book.html. For information about all Cisco IOS commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or the Cisco IOS Master Command List, All Releases, at http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html.

•ip nat service enable-sym-port

Feature Information for Endpoint Agnostic Port Allocation

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 12.4(24)T or a later release appear in the table.

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, Catalyst OS, and Cisco IOS XE 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 NAT Endpoint Agnostic Port Allocation

Feature Name
Releases
Feature Information

FPG: Endpoint Agnostic Port Allocation

12.4(24)T

This feature was introduced.


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Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.

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