Table Of Contents
Redirecting Subscriber Traffic Using ISG Layer 4 Redirect
Prerequisites for Redirecting ISG Subscriber Traffic
Restrictions for Redirecting ISG Subscriber Traffic
Information About Redirecting ISG Subscriber Traffic
Overview of ISG Layer 4 Redirect
How to Configure ISG Layer 4 Redirect
Defining a Redirect Server Group
Configuring Layer 4 Redirection in a Service Policy Map
Configuring Layer 4 Redirection in a Service Profile or User Profile on the AAA Server
Verifying ISG Traffic Redirection
Configuration Examples for ISG Layer 4 Redirect
Redirecting Unauthenticated Subscriber Traffic: Example
Redirecting Unauthorized Subscriber Traffic: Example
Redirecting DNS Traffic: Example
Feature Information for Redirecting ISG Subscriber Traffic
Redirecting Subscriber Traffic Using ISG Layer 4 Redirect
First Published: March 20, 2006Last Updated: June 10, 2010Intelligent 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
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 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
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Prerequisites for Redirecting ISG Subscriber Traffic
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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.
A Layer 4 Redirect feature and a Traffic-Class (TC) service containing a Layer 4 Redirect feature cannot be applied on the same session. A Layer 4 Redirect feature can be either applied on a session or a TC on the session.
In Cisco IOS XE software, access lists cannot be configured as match criteria in an ISG Layer 4 redirect configuration. As an alternative, Layer 4 redirect should be configured in ISG traffic class services.
Information About Redirecting ISG Subscriber Traffic
Before you configure the Layer 4 Redirect feature, you should understand the following concepts:
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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:
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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.
Layer 4 Redirect Applications
The Layer 4 Redirect feature supports the following applications:
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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.
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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.
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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.
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DNS queries may be redirected to a local DNS server. In some deployments, such as public wireless LAN (PWLAN) hotspots, 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.
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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.
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Configuring Layer 4 Redirection in a Service Policy Map
Perform this task to configure ISG 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.
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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 module "Configuring ISG Subscriber Services".
Configuring Layer 4 Redirection in a Service Profile 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 non-TC service profiles simultaneously.
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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.
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Examples
The following is sample output from the show redirect translations command:
Router# show redirect translations ip 10.53.0.2Destination IP/port Server IP/port Prot In Flags Out Flags Timestamp172.20.0.2 23 10.2.36.253 23 TCP none none May 08 2003 12:37:10The 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 135Subscriber session handle: 7C000114, state: connected, service: Local TermUnique Session ID: 135Identifier: blind-rdtSIP subscriber access type(s): IP-InterfaceRoot SIP Handle: CF000020, PID: 73Current SIP options: Req Fwding/Req FwdedSession Up-time: 40 minutes, 30 seconds, Last Changed: 40 minutes, 30 secondsAAA unique ID: 135Switch handle: F000086Interface: ATM2/0.53Policy information:Authentication status: unauthenConfig downloaded for session policy:From Access-Type: IP-Interface, Client: SM, Event: Service Selection Request, ServiceProfile name: blind-rdt, 2 referencesusername "blind-rdt"l4redirect "redirect to group sesm-grp"Rules, actions and conditions executed:subscriber rule-map blind-rdtcondition always event session-startaction 1 service-policy type service name blind-rdtSession inbound features:Feature: Layer 4 RedirectRule Cfg Definition#1 SVC Redirect to group sesm-grp !! applied redirectConfiguration sources associated with this session:Service: blind-rdt, Active Time = 40 minutes, 32 secondsInterface: ATM2/0.53, Active Time = 40 minutes, 32 secondsThe 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 133Subscriber session handle: D7000110, state: connected, service: Local TermUnique Session ID: 133Identifier:SIP subscriber access type(s): IP-InterfaceRoot SIP Handle: 1E, PID: 73Current SIP options: Req Fwding/Req FwdedSession Up-time: 42 minutes, 54 seconds, Last Changed: 42 minutes, 54 secondsAAA unique ID: 133Switch handle: 17000084Interface: FastEthernet0/0.505Policy information:Authentication status: unauthenSession inbound features:Feature: Layer 4 RedirectRule Cfg Definition#1 INT Redirect to group sesm-grpConfiguration sources associated with this session:Interface: FastEthernet0/0.505, Active Time = 42 minutes, 54 secondsConfiguration Examples for ISG Layer 4 Redirect
This section contains the following examples:
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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-POLICYpolicy-map type control DEFAULT-IP-POLICYclass type control always event session-start1 service-policy type service BLIND-RDT!class type control always event account-logon1 authenticate aaa list AUTH-LIST2 service-policy type service unapply BLIND-RDTpolicy-map type service BLIND-RDTclass type traffic CLASS-ALLredirect to group PORTAL!redirect server-group PORTALserver 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 in to the service, the traffic is no longer redirected. When the subscriber logs out of 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_110match access-group input 100match access-group output 110!policy-map type service blind-rdtclass type traffic CLASS-ALLredirect to group PORTAL!policy-map type service svc-rdtclass type traffic CLASS-ALLredirect to group PORTAL!policy-map type service svcclass type traffic CLASS-100_110class type traffic default in-outdrop!
policy-map type control THE_RULEclass type control alwyas event account-logon1 authenticate2 service-policy type service name svc-rdtclass type control cond-svc-logon event service-start1 service-policy type service unapply name svc-rdt2 service-policy type service identifier service-nameclass type control cond-svc-logon event service-stop1 service-policy type service unapply name svc2 service-policy type service name svc-rdt!class-map type control match-all cond-svc-logonmatch identifier service-name svc!redirect server-group PORTALserver ip 10.2.36.253 port 80
Initial 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-rdtpolicy-map type control intial-rdtclass type control always event session-start1 service-policy type service name initial-rdt-profile!policy-map type service initial-rdt-profileclass type traffic CLASS-ALLredirect to group ADVT duration 60
Periodic 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-rdtclass type control always event session-start1 service-policy service periodic-rdt-profile!policy-map type service periodic-rdt-profileredirect 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-rdtclass type control event session-start1 service-policy type service name DNS-rdt-profile!policy-map type service DNS-rdt-profileclass type traffic CLASS-ALLredirect to group DNS-serverAdditional References
The following sections provide references related to the ISG Layer 4 Redirect feature.
Related Documents
Technical Assistance
Feature Information for Redirecting ISG Subscriber Traffic
Table 1 lists the features in this module and provides links to specific configuration information. For information on a feature in this technology that is not documented here, see the Cisco IOS XE Release ISG Configuration Guide Roadmap.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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