Guest

Networking Software (IOS & NX-OS)

Redirecting Subscriber Traffic Using ISG Layer 4 Redirect

Hierarchical Navigation

Downloads

Table Of Contents

Redirecting Subscriber Traffic Using ISG Layer 4 Redirect

Finding Feature Information

Contents

Prerequisites for Redirecting ISG Subscriber Traffic

Restrictions for Redirecting ISG Subscriber Traffic

Information About Redirecting ISG Subscriber Traffic

Overview of ISG Layer 4 Redirect

Layer 4 Redirect Applications

How to Configure ISG Layer 4 Redirect

Defining a Redirect Server Group

Configuring Layer 4 Redirection in a Service Policy Map

Prerequisites

Restrictions

Configuring Layer 4 Redirection in a Service or User Profile on the AAA Server

What to Do Next

Verifying ISG Traffic Redirection

Examples

Configuration Examples for ISG Layer 4 Redirect

Redirecting Unauthenticated Subscriber Traffic: Example

Redirecting Unauthorized Subscriber Traffic: Example

Initial ISG Redirection: Example

Periodic ISG Redirection: Example

Redirecting DNS Traffic: Example

Redirection for PPP Sessions: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Redirecting ISG Subscriber Traffic


Redirecting Subscriber Traffic Using ISG Layer 4 Redirect

First Published: March 20, 2006
Last Updated: April 20, 2010

Intelligent Services Gateway (ISG) is a Cisco IOS software feature set that provides a structured framework in which edge devices can deliver flexible and scalable services to subscribers. This module describes how to configure ISG to redirect subscriber traffic by using the ISG Layer 4 Redirect feature. The ISG Layer 4 Redirect feature enables service providers to better control the user experience by allowing subscriber TCP or User Datagram Protocol (UDP) packets to be redirected to specified servers for appropriate handling. ISG Layer 4 redirection can be used to facilitate subscriber authentication, initial and periodic advertising captivation, redirection of application traffic, and Domain Name System (DNS) redirection.

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 Redirecting ISG Subscriber Traffic" 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 Redirecting ISG Subscriber Traffic

•Restrictions for Redirecting ISG Subscriber Traffic

•Information About Redirecting ISG Subscriber Traffic

•How to Configure ISG Layer 4 Redirect

•Configuration Examples for ISG Layer 4 Redirect

•Additional References

•Feature Information for Redirecting ISG Subscriber Traffic

Prerequisites for Redirecting ISG Subscriber Traffic

For information about release and platform support, see the "Feature Information for Redirecting ISG Subscriber Traffic" section.

Restrictions for Redirecting ISG Subscriber Traffic

The ISG Layer 4 Redirect feature applies only to TCP or UDP traffic.

Beginning in Cisco IOS Release 12.2(33)SRC, this feature is available on the Cisco 7600 router, with the following limitation: The Layer 4 Redirect feature must be configured using an Access Control List (ACL) because the Cisco 7600 router does not support the traffic class feature.

Information About Redirecting ISG Subscriber Traffic

Before you configure the Layer 4 Redirect feature, you should understand the following concepts:

•Overview of ISG Layer 4 Redirect

•Layer 4 Redirect Applications

Overview of ISG Layer 4 Redirect

The ISG Layer 4 Redirect feature redirects specified packets to servers that handle the packets in a specified manner. For example, packets sent upstream by unauthorized users can be forwarded to a server that redirects the users to a login page. Similarly, if users try to access a service to which they have not logged in, the packets can be redirected to a server that provides a service login screen.

The Layer 4 Redirect feature supports three types of redirection, which can be applied to subscriber sessions or to flows:

•Initial redirection—Specified traffic is redirected for a specific duration of the time only, starting from when the feature is applied.

•Periodic redirection—Specified traffic is periodically redirected. The traffic is redirected for a specified duration of time. The redirection is then suspended for another specified duration. This cycle is repeated. During periodic redirect, all new TCP connections are redirected until the duration of the redirect is over. After that time any new incoming TCP connections will not be redirected. However, all existing TCP connections that were initiated during this redirection will still be redirected so as not to break the connections.

•Permanent redirection—Specified traffic is redirected to the specified server all the time.

A redirect server can be any server that is programmed to respond to the redirected packets. If ISG is used with a web portal, unauthenticated subscribers can be sent automatically to a login page when they start a browser session. Web portal applications can also redirect to service login pages, advertising pages, and message pages.

Redirected packets are sent to an individual redirect server or redirect server group that consists of one or more servers. ISG selects one server from the group on a rotating basis to receive the redirected packets.

When traffic is redirected, ISG modifies the destination IP address and TCP port of upstream packets to reflect the destination server. For downstream packets, ISG changes the destination IP address and port to the original packet's source.

When traffic is selected by a policy map that includes a redirection command, packets are fed back into the policy map classification scheme for a second service selection. The modified IP headers can be subject to different classification criteria. For example, if two class maps exist, each with different redirection commands, packets could be redirected, selected by the first class map, and redirected a second time. To avoid this situation, configure traffic class maps so that two consecutive redirections cannot be applied to the same packet.

Layer 4 Redirect Applications

The Layer 4 Redirect feature supports the following applications:

•TCP redirection for unauthenticated users and unauthorized services

HTTP traffic from subscribers can be redirected to a web dashboard where the subscribers can log in so that authentication and authorization can be performed.

•Initial and periodic redirection for advertising captivation

Subscriber traffic can be redirected to a sponsor's web page for a brief period of time at the start of the session or periodically throughout the session.

•Redirection of application traffic

Application traffic from a subscriber can be redirected so as to provide value-added services. For example, a subscriber's Simple Mail Transfer Protocol (SMTP) traffic can be redirected to a local mail server that can function as a forwarding agent for the mail.

•DNS redirection

DNS queries may be redirected to a local DNS server. In some deployments, such as public wireless LAN (PWLAN) hot spots, subscribers may have a static DNS server addresses, which may not be reachable at certain locations. Redirecting DNS queries to a local DNS server allows applications to work properly without requiring reconfiguration.

How to Configure ISG Layer 4 Redirect

There are three ways to apply Layer 4 redirection to sessions. One way is to configure redirection directly on a physical main interface or logical subinterface. A second way is to configure a service profile or service policy map with the Layer 4 redirect attribute in it, and apply that service to the session. A third way is to configure the Layer 4 redirect attribute in the user profile.

The following tasks describe how to configure Layer 4 redirection. The first task is optional. One or more of the next three tasks is required. The last task is optional.

For examples of Layer 4 redirection configuration for specific applications (such as unauthenticated user redirect), see the "Configuration Examples for ISG Layer 4 Redirect" section.

•Defining a Redirect Server Group

•Configuring Layer 4 Redirection in a Service Policy Map

•Configuring Layer 4 Redirection in a Service or User Profile on the AAA Server

•Verifying ISG Traffic Redirection

Defining a Redirect Server Group

Perform this task to define a group of one or more servers to which traffic will be redirected. Traffic will be forwarded to servers on a rotating basis.

SUMMARY STEPS

1. enable

2. configure terminal

3. redirect server-group group-name

4. server ip ip-address port port-number

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 

redirect server-group group-name

Example:

Router(config)# redirect server-group ADVT-SERVER

Enters redirect server-group configuration mode to define a group of servers in a named redirection server group.

Step 4 

server ip ip-address port port-number

Example:

Router(config-sg-l4redirect-group)# server ip 10.0.0.1 port 8080

Adds a server to a redirect server group.

•You can enter this command more than one time to add multiple servers to the server group.

Configuring Layer 4 Redirection in a Service Policy Map

Perform this task to configure Layer 4 redirection in a service policy map.

Prerequisites

The ISG Layer 4 Redirect feature is configured under a traffic class within a service policy map. This task assumes that you have defined the traffic class map. See the "Configuring ISG Subscriber Services" module for more information.

Restrictions

Only ISG policing and accounting features can be enabled in conjunction with redirection on the same service policy.

SUMMARY STEPS

1. enable

2. configure terminal

3. redirect session-limit maximum-number

4. policy-map type service policy-map-name

5. class type traffic class-name

6. redirect to {group server-group-name | ip ip-address [port port-number]} [duration seconds] [frequency seconds]

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 

redirect session-limit maximum-number

Example:

Router(config)# redirect session-limit 5

(Optional) Sets the maximum number of Layer 4 redirects allowed for each subscriber session.

Step 4 

policy-map type service policy-map-name

Example:

Router(config)# policy-map type service service1

Enters service policy-map configuration mode to create or modify a service policy map, which is used to define an ISG service.

Step 5 

class type traffic class-name

Example:

Router(config-service-policymap)# class type traffic class1

(Optional) Enters traffic class map configuration mode to specify a traffic class map that identifies the traffic to which this service applies.

Step 6 

redirect to {group server-group-name | ip ip-address [port port-number]} [duration seconds] [frequency seconds]

Example:

Router(config-service-policymap-class-traffic)# redirect to ip 10.10.10.10

Redirects traffic to a specified server or server group.

What to Do Next

You may want to configure a method of activating the service policy map; for example, control policies can be used to activate services. For more information about methods of service activation, see the "Configuring ISG Subscriber Services" module.

Configuring Layer 4 Redirection in a Service or User Profile on the AAA Server

The Layer 4 Redirect feature can be configured as a Cisco vendor-specific attribute (VSA) in a user or service profile on an authentication, authorization, and accounting (AAA) server. This attribute can appear more than once in a profile to define different types of redirections for a session and can be used in both user and service profiles simultaneously.

SUMMARY STEPS

1. Add the Layer 4 Redirect VSA to the user profile or service profile on the AAA server.

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

Add the Layer 4 Redirect VSA to the user profile or subscriber profile on the AAA server.

Cisco-AVPair = "ip:l4redirect=redirect to {group server-group-name | ip ip-address [port port-number]} [duration seconds] [frequency seconds]"

Redirects traffic to a specified server or server group.

What to Do Next

If you configure ISG Layer 4 redirection in a service profile, you may want to configure a method of activating the service profile; for example, control policies can be used to activate services. For more information about methods of service activation, see the "Configuring ISG Subscriber Services" module.

Verifying ISG Traffic Redirection

Perform this task to verify the configuration and operation of ISG Layer 4 traffic redirection. The commands can be used in any order.

SUMMARY STEPS

1. enable

2. show redirect translations [ip ip-address]

3. show redirect group [group-name]

4. show subscriber session [detailed] [identifier identifier | uid session-id | username name]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

show redirect translations [ip ip-address]

Example:

Router# show redirect translations ip 10.0.0.0

Displays ISG Layer 4 redirect translations for sessions.

Step 3 

show redirect group [group-name]

Example:

Router# show redirect group redirect1

Displays information about ISG redirect server groups.

Step 4 

show subscriber session [detailed] [identifier identifier | uid session-id | username name]

Example:

Router# show subscriber session detailed

Displays ISG subscriber session information.

Examples

The following is sample output from the show redirect translations command showing the number of active redirect translations: 

Router# show redirect translations


Load for five secs: 1%/0%; one minute: 2%; five minutes: 2%

Time source is hardware calendar, *11:48:06.383 PST Wed Oct 21 2009

Maximum allowed number of L4 Redirect translations per session: 5


Destination IP/port    Server IP/port    Prot  In Flags  Out Flags  Timestamp

10.0.1.2        23     10.0.2.2   23     TCP                        Oct 21 2009 11:48:01

10.0.1.2        23     10.0.2.2   23     TCP                        Oct 21 2009 11:48:01

10.0.1.2        23     10.0.2.2   23     TCP                        Oct 21 2009 11:48:01


Total Number of Translations: 3


Highest number of L4 Redirect: 3 by session with source IP 10.0.0.2

The following is sample output from the show subscriber session command. This output shows that Layer 4 redirect is being applied from the service profile. 

Router# show subscriber session uid 135


Subscriber session handle: 7C000114, state: connected, service: Local Term

Unique Session ID: 135

Identifier: blind-rdt

SIP subscriber access type(s): IP-Interface

Root SIP Handle: CF000020, PID: 73

Current SIP options: Req Fwding/Req Fwded

Session Up-time: 40 minutes, 30 seconds, Last Changed: 40 minutes, 30 seconds

AAA unique ID: 135

Switch handle: F000086

Interface: ATM2/0.53


Policy information:

  Authentication status: unauthen

  Config downloaded for session policy:

  From Access-Type: IP-Interface, Client: SM, Event: Service Selection Request, Service

    Profile name: blind-rdt, 2 references 

      username             "blind-rdt"

      l4redirect           "redirect to group sesm-grp"

  Rules, actions and conditions executed:

    subscriber rule-map blind-rdt

      condition always event session-start

        action 1 service-policy type service name blind-rdt


Session inbound features:

 Feature: Layer 4 Redirect

  Rule  Cfg  Definition

  #1    SVC  Redirect to group sesm-grp  !! applied redirect

Configuration sources associated with this session:

Service: blind-rdt, Active Time = 40 minutes, 32 seconds

Interface: ATM2/0.53, Active Time = 40 minutes, 32 seconds

The following is sample output from the show subscriber session command for a session in which the Layer 4 redirection is applied on the interface: 

Router# show subscriber session uid 133


Subscriber session handle: D7000110, state: connected, service: Local Term

Unique Session ID: 133

Identifier: 

SIP subscriber access type(s): IP-Interface

Root SIP Handle: 1E, PID: 73

Current SIP options: Req Fwding/Req Fwded

Session Up-time: 42 minutes, 54 seconds, Last Changed: 42 minutes, 54 seconds

AAA unique ID: 133

Switch handle: 17000084

Interface: FastEthernet0/0.505


Policy information:

  Authentication status: unauthen


Session inbound features:

 Feature: Layer 4 Redirect

  Rule  Cfg  Definition

  #1    INT  Redirect to group sesm-grp 

Configuration sources associated with this session:

Interface: FastEthernet0/0.505, Active Time = 42 minutes, 54 seconds

Configuration Examples for ISG Layer 4 Redirect

This section contains the following examples:

•Redirecting Unauthenticated Subscriber Traffic: Example

•Redirecting Unauthorized Subscriber Traffic: Example

•Initial ISG Redirection: Example

•Periodic ISG Redirection: Example

•Redirecting DNS Traffic: Example

•Redirection for PPP Sessions: Example

Redirecting Unauthenticated Subscriber Traffic: Example

In the following example, Layer 4 redirection is configured in the service policy map "BLIND-RDT." This policy is applied to all sessions at session start and redirects subscriber TCP traffic to the server group called "PORTAL." At account login the subscriber is authenticated and the redirection is not applied. 

Service-policy type control DEFAULT-IP-POLICY


policy-map type control DEFAULT-IP-POLICY

 class type control always event session-start

  1 service-policy type service BLIND-RDT

!

 class type control always event account-logon

  1 authenticate aaa list AUTH-LIST

  2 service-policy type service unapply BLIND-RDT


policy-map type service BLIND-RDT

 class type traffic CLASS-ALL

  redirect to group PORTAL

!

redirect server-group PORTAL

 server ip 10.2.36.253 port 80

Redirecting Unauthorized Subscriber Traffic: Example

The following example shows the configuration of redirection for unauthorized subscribers. If the subscriber is not logged into the service called "svc," traffic that matches "svc" is redirected to the server group "PORTAL." Once the subscriber logs on to the service, the traffic is no longer redirected. When the subscriber logs off the service, redirection is applied again. 

service-policy type control THE_RULE

!

class-map type traffic match-any CLASS-ALL

!

class-map type traffic match-any CLASS-100_110

 match access-group input 100 

 match access-group output 110

!

policy-map type service blind-rdt

 class type traffic CLASS-ALL

  redirect to group PORTAL

!

policy-map type service svc-rdt

 class type traffic CLASS-ALL

  redirect to group PORTAL

!

policy-map type service svc

 class type traffic CLASS-100_110

 class type traffic default in-out

  drop

! 

policy-map type control THE_RULE

 class type control alwyas event account-logon

  1 authenticate

  2 service-policy type service name svc-rdt

 class type control cond-svc-logon event service-start

  1 service-policy type service unapply name svc-rdt

  2 service-policy type service identifier service-name

 class type control cond-svc-logon event service-stop

  1 service-policy type service unapply name svc

  2 service-policy type service name svc-rdt

 !

class-map type control match-all cond-svc-logon

 match identifier service-name svc 

!

redirect server-group PORTAL

server ip 10.2.36.253 port 80

Initial ISG Redirection: Example

The following example shows ISG configured to redirect the Layer 4 traffic of all subscribers to a server group called "ADVT" for the initial 60 seconds of the session. After the initial 60 seconds, ISG will stop redirecting the traffic for the rest of the lifetime of the session. 

service-policy type control initial-rdt

policy-map type control intial-rdt

 class type control always event session-start

  1 service-policy type service name initial-rdt-profile

 !

policy-map type service initial-rdt-profile

 class type traffic CLASS-ALL

  redirect to group ADVT duration 60

Periodic ISG Redirection: Example

The following example shows how to redirect all subscriber traffic for a period of 60 seconds every 3600 seconds: 

service-policy control periodic-rdt session-start

!

policy-map type control periodic-rdt

 class type control always event session-start

  1 service-policy service periodic-rdt-profile

 !

policy-map type service periodic-rdt-profile

redirect to group ADVT duration 60 frequency 3600

Redirecting DNS Traffic: Example

The following example shows how to redirect all subscriber DNS packets to the server group "DNS-server":

service-policy type control DNS-rdt 

policy-map type control DNS-rdt

 class type control event session-start

  1 service-policy type service name DNS-rdt-profile

  !

policy-map type service DNS-rdt-profile

 class type traffic CLASS-ALL

  redirect to group DNS-server

Redirection for PPP Sessions: Example

The following example shows how to configure Layer 4 redirection for PPP sessions: 

class-map type traffic match-any CLASS-L4R

!

policy-map type service svc-rdt

 class type traffic CLASS-L4R

  redirect to group PORTAL

!

policy-map type control THE_RULE

 class type control alwyas event session-start

  1 authenticate

  2 service-policy type service name svc-rdt

!

redirect server-group PORTAL

server ip 10.2.36.253 port 80 

!

Note No authentication should be configured on the virtual template. If configured, an authenticate action should be included in the control policy and the authentication should be successful even for users who will get redirected.

Additional References

The following sections provide references related to the ISG Layer 4 Redirect feature.

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

ISG commands

Cisco IOS Intelligent Services Gateway Command Reference

Configuring ISG subscriber services

"Configuring ISG Subscriber Services" section of the Cisco IOS Intelligent Services Gateway Configuration Guide


Standards

Standard
Title

None

—


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

None

—


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/cisco/web/support/index.html


Feature Information for Redirecting ISG Subscriber Traffic

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(28)SB or later releases appear in the table. If you are looking for information on a feature in this technology that is not documented here, see the "Intelligent Services Gateway Features Roadmap."

Not all commands may be available in your Cisco IOS software release. For details on when support for specific commands was introduced, see the command reference documents.

Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. 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.

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 Redirecting ISG Subscriber Traffic 

Feature Name
Releases
Feature Information

ISG: Flow Control: Flow Redirect

12.2(28)SB
12.2(33)SRC
12.2(33)XNE

The ISG Layer 4 Redirect feature enables service providers to better control the user experience by allowing subscriber TCP or UDP packets to be redirected to specified servers for appropriate handling. ISG Layer 4 redirection can be applied to individual subscriber sessions or flows.

The following sections provide information about this feature:

•Information About Redirecting ISG Subscriber Traffic

•How to Configure ISG Layer 4 Redirect

In Cisco IOS Release 12.2(33)SRC, support was added for the Cisco 7600 router.

This feature was integrated into Cisco IOS Release 12.2(33)XNE.


Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)


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.

© 2006-2010 Cisco Systems, Inc. All rights reserved.