Configuring ISG Access for IP Subscriber Sessions
First Published: December 5, 2006
Last Updated: January 6, 2011
Intelligent Services Gateway (ISG) is a Cisco IOS XE software feature set that provides a structured framework in which edge devices can deliver flexible and scalable services to subscribers. ISG supports IP sessions for subscribers who connect to ISG from routed, Layer 2 or Layer 3 access networks. This module describes how to configure ISG to bring up IP subscriber sessions, manage subscriber IP addressing, and configure dynamic Virtual Private Network (VPN) selection.
Note This document assumes that Network Address Translation is performed on a Layer 3 gateway other than the ISG.
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 ISG Access for IP Subscriber Sessions" section.
Use Cisco Feature Navigator to find information about platform support and Cisco 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 ISG Access for IP Subscriber Sessions
•Restrictions for ISG Access for IP Subscriber Sessions
•Information About ISG Access for IP Subscriber Sessions
•How to Configure ISG for IP Subscriber Sessions
•Configuration Examples for ISG Access for IP Subscriber Sessions
•Additional References
•Feature Information for ISG Access for IP Subscriber Sessions
Prerequisites for ISG Access for IP Subscriber Sessions
For information about release and platform requirements, see the "Feature Information for ISG Access for IP Subscriber Sessions" section.
The Dynamic Host Configuration Protocol (DHCP) server must support the DHCP lease protocol.
Restrictions for ISG Access for IP Subscriber Sessions
Overlapping IP Address Restrictions
Overlapping IP addresses in the same virtual routing and forwarding (VRF) instance are not supported.
Overlapping IP subscribers in different VRFs are not supported on the same interface for static IP subscriber sessions and routed IP subscriber sessions. Overlapping IP subscribers in different VRFs are supported on the same interface for Layer 2 connected DHCP subscriber sessions.
IP Subnet Session Restrictions
IP subnet sessions are not supported on an interface configured with the ip subscriber l2-connected command. IP subnet sessions are supported only when the ip subscriber routed command is configured on the interface.
ISG DHCP Restrictions
ISG cannot relay DHCP requests when a Layer 3 DHCP relay agent is between the ISG device and subscriber devices.
Dynamic VPN Selection Restrictions
Dynamic VPN selection is not supported for IP subnet sessions and subscribers coming in on nonglobal VRF interfaces.
Dynamic VPN selection is not supported for subscribers with a static VPN configuration on the access interface.
Dynamic VPN selection with address reassignment is not supported for routed IP subscriber sessions that are initiated by DHCP. IP addresses of routed IP subscribers must be routable in the access network. Because Internet service provider (ISP) or VRF-owned private addresses could overlap or be unroutable in the network between subscribers and the ISG device, it is not possible to assign IP addresses to those subscribers.
IP interface sessions do not support dynamic VRF; only static VRF is supported. If an interface is configured with the ip subscriber interface command, dynamic VRF through a RADIUS VSA is not supported, only static VRF is supported.
General IP Session Restrictions
IP subscriber sessions are not supported on ambiguous IEEE 802.1QinQ (QinQ) or IEEE 802.1Q (Dot1Q) subinterfaces.
IP subscriber sessions are not supported on interfaces that receive Multiprotocol Label Switching (MPLS) packets.
Configuring features on static IP sessions is not supported.
ISG IP subscriber functionality is not supported on the following types of access interfaces:
•Gigabit EtherChannel (Port Channel)
•Generic routing encapsulation (GRE)
•PPP (virtual-template)
•Layer 2 Tunnel Protocol (L2TP)
Interface statistics are not generated for ISG multiservice interfaces.
Stateful switchover (SSO) and In Service Software Upgrade (ISSU) are not supported for any features on ISG IP subscriber sessions or traffic class sessions. Upon switchover, an IP session must be re-created or restarted (for DHCP sessions) when the session becomes active again.
The following subscriber features are not supported on IPoE sessions:
•Per-session firewall
•Per-session NAT
•Per-session PBR
•Per-session NBAR
•Per-session netflow
•Per-session multicast
The following PPP session features are not supported on IP sessions:
•Session limit per system, VLAN, or MAC
•Dual stack session (single PPP session carrying both IPv4 and IPv6 traffic)
•Packet of Disconnect (PoD)
Multiservice Interface Restrictions
IP interface features (such as QoS and access lists) are not supported on multiservice interfaces.
Only one multiservice interface can belong to a single VRF. For example, the following configuration will not work:
Information About ISG Access for IP Subscriber Sessions
•Types of IP Subscriber Sessions
•IP Subscriber Connectivity
•IP Subscriber Session Initiation
•IP Subscriber Addressing
•IP Subscriber Identity
•VPN Connectivity and Services for IP Subscribers
•IP Session Termination
•IP Session Recovery for DHCP-Initiated IP Sessions
•Default Services for IP Subscriber Sessions
Types of IP Subscriber Sessions
ISG supports the following types of IP subscriber sessions on Cisco IOS XE software:
•IP Sessions
•IP Interface Sessions
•IP Subnet Sessions
IP Sessions
An IP session includes all the traffic that is associated with a single subscriber IP address. If the IP address is not unique to the system, other distinguishing characteristics such as a VRF or MAC address form part of the identity of the session. ISG can be configured to create IP sessions upon receipt of DHCP packets, packets with unclassified IP or MAC addresses, or RADIUS packets. See the "IP Subscriber Session Initiation" section for more information.
IP sessions may be hosted for a connected subscriber device (one routing hop from the ISG) or one that is more than one hop from the gateway.
IP Interface Sessions
An IP interface session includes all IP traffic received on a specific physical or virtual interface. IP interface sessions are provisioned through the CLI; that is, a session is created when the IP interface session commands are entered, and the session is continuous, even when the interface is shut down. By default, IP interface sessions come up in the state "unauthenticated" with full network access.
IP interface sessions might be used in situations in which a subscriber is represented by an interface (with the exception of PPP) and communicates using more than one IP address. For example, a subscriber using routed bridge encapsulation (RBE) access might have a dedicated ATM virtual circuit (VC) to home customer premises equipment (CPE) that is hosting a number of PCs.
IP Subnet Sessions
An IP subnet session represents all the traffic that is associated with a single IP subnet. IP subnet sessions are used to apply uniform edge processing to packets associated with a particular IP subnet. When an IP subnet session is configured, ISG treats the subnet as a single subscriber, which means that ISG features and functionality are applied to the subnet traffic as an aggregate.
IP subnet sessions are supported for routed IP subscriber traffic.
IP subnet sessions are created the same way as IP sessions, except that when a subscriber is authorized or authenticated and the Framed-IP-Netmask attribute is present in the user or service profile, ISG converts the source-IP-based session into a subnet session with the subnet value in the Framed-IP-Netmask attribute.
Note Where an ingress interface maps to a single subnet, the subnet might be accommodated with an IP interface session. However, if the ISG is more than one hop away from a subscriber, and there is the possibility that multiple subnets are accessible through the same interface, IP subnet sessions may be defined to distinguish the traffic and apply appropriate edge functionality to each subnet.
Coexistence of Multicast and IP Sessions
The ISG Session Multicast Coexistence feature introduces the ability to host all the subscribers and services (data and multicast) on the same VLAN by enabling multicast and IP sessions to coexist on the same subinterface for Cisco ASR 10000 Series Aggregation Routers. ISG IP sessions are supported on nonaccess-type subinterfaces. In the case of an existing session or even when no session exists, this support helps the multicast traffic to pass through the interfaces configured for the IP sessions in both upstream and downstream directions without creating a session.
IP Subscriber Connectivity
IP subscribers connect to ISG through either Layer 2 connected access networks or routed access networks. The following sections describe these types of IP subscriber connectivity:
•Layer 2 Connected Access Networks
•Routed Access Networks
Layer 2 Connected Access Networks
Layer 2 connected subscribers are either directly attached to the physical interfaces of an ISG or connected to an ISG through a Layer 2 access network, such as a bridged or a switched network. Layer 3 forwarding is either absent or not used to direct subscriber traffic in the Layer 2 access network. IP addresses of the subscribers may or may not be on the same subnet as the Layer 2 connected physical interfaces. Figure 1 shows an example of a Layer 2 connected access network.
Figure 1 Layer 2 Connected Access Network
Routed Access Networks
Routed subscriber traffic is routed through a Layer 3 access network with at least one transit router before reaching the ISG. IP addresses of the subscribers are at least routable in the Layer 3 access network. Layer 3 access networks contain a single routing domain and therefore do not support overlapping IP addresses. Figure 2 shows an example of a routed access network.
Figure 2 Routed Access Network
IP Subscriber Session Initiation
ISG can be configured to allow one or more of the following events to signal the start of an IP session or IP subnet session on an interface:
•DHCP DISCOVER packet
If the following conditions are met, receipt of a DHCP DISCOVER packet will trigger the creation of an IP session:
–The ISG serves as a DHCP relay or server for new IP address assignments.
–Subscribers are configured for DHCP.
–The DHCP DISCOVER packet is the first DHCP request received from the subscriber.
•Unclassified source IP address
For routed IP subscribers, a new IP session is triggered by the appearance of an IP packet with an unclassified source IP address (which means that an IP session does not yet exist for that IP address).
•Unclassified source MAC address
For Layer 2 connected IP subscribers, a new IP session is triggered by the appearance of an IP packet with an unclassified source MAC address (which means that an IP session does not yet exist for that MAC address).
•RADIUS Access-Request packet
For routed or Layer 2 connected access, a new IP session is triggered by the appearance of a RADIUS Access-Request packet when ISG is serving as a RADIUS proxy.
IP Subscriber Addressing
The following sections provide information about how ISG handles IP addressing for IP subscribers:
•Methods of ISG Subscriber IP Address Assignment
•Public and Private IP Addresses
•Overlapping IP Addresses
•ISG Subscriber IP Address Assignment Using DHCP
Methods of ISG Subscriber IP Address Assignment
IP subscribers either have IP addresses configured statically or obtain IP addresses dynamically through some network protocol that has the ability to assign IP addresses. For a subscriber to be routable within a given IP service domain, the subscriber must present a domain-specific IP address to the network. If a subscriber transfers between IP service domains (which include any private domain managed by the access provider), the IP address presented to the network must change to reflect the new domain.
The following sections describe the methods of IP address assignment that ISG supports for each type of Layer 3 session:
•IP Interface Sessions
•IP Sessions
•IP Subnet Sessions
IP Interface Sessions
For IP interface sessions, ISG is not involved in (or aware of) the assignment of subscriber IP addresses.
IP Sessions
For IP sessions, ISG supports the following methods of IP address assignment:
•Static IP addresses
If a subscriber's static IP address is configured correctly for the service domain, ISG does not have to be involved in the assignment of an IP address for the subscriber.
•DHCP
If DHCP is being used to assign IP addresses, and the IP address that is assigned by DHCP is correct for the service domain, ISG does not have to be involved in the assignment of an IP address for the subscriber.
If the IP address that is assigned by DHCP is not correct for the service domain, or if the domain changes because of a VRF transfer, ISG can be configured to influence the DHCP IP address assignment.
The following conditions must be met in order for ISG to influence DHCP IP address assignment:
–The subscriber must be Layer 2 connected.
–The ISG device must be in the path of DHCP requests by serving as a DHCP server or relay.
–Subscribers must not have statically configured IP addresses.
For deployments that support it, DHCP is the recommended method of IP address assignment.
IP Subnet Sessions
For IP subnet sessions, the IP subnet is specified in the user profile.
Public and Private IP Addresses
No matter how an IP subscriber is assigned an IP address, the IP address falls in either the public or the private IP address category. If an IP subscriber is assigned with a private IP address and the subscriber has to reach the Internet, a Layer 3 gateway, such as ISG or a firewall, between the subscriber and the Internet must perform Network Address Translation (NAT) for the subscriber's private IP address.
When the access network is a Layer 2 connected network, a subscriber IP address can be either native or foreign to an access interface. A native subscriber IP address is one that belongs to the subnet provisioned on the access interface. A foreign subscriber IP address is one that does not belong to the subnet provisioned on the access interface. A foreign subscriber IP address could result when a retail ISP assigns an IP address to the IP subscriber from its own IP address allotment, which is different from the wholesale ISPs, or when an IP subscriber with a static IP address that is native in the home access network roams to a foreign access network. To support IP subscribers with foreign IP addresses, ISG must be able to respond to Address Resolution Protocol (ARP) requests that originate from foreign IP addresses with a MAC address of the ISG itself. Because the access network is Layer 2 connected, ISG maintains an adjacency to every subscriber.
When the access network is a routed network, a subscriber IP address must be routable in the access network; otherwise, subscriber traffic will never be able to reach ISG. ISG may not have an adjacency for each subscriber in this case, but rather an adjacency of the next hop toward a subscriber. The next hop is determined by the routing process on ISG.
Overlapping IP Addresses
When an access network is deployed without VPN capability, the IP address space in the access network is shared among all IP subscribers. When the IP addresses are assigned dynamically, care must be taken to ensure that these addresses do not overlap. In cases where overlapping IP addresses are assigned to IP subscribers intentionally, the access network should use a Layer 2 separation mechanism to differentiate the IP address spaces. For example, the access network may put each IP address space in a different VLAN.
In cases in which the access network serves both local IP subscribers and roaming users, the static private IP address of a roaming subscriber may overlap the native private IP address of another subscriber. For example, a public wireless hot spot that generally assigns dynamic IP addresses might want to provide access to occasional roaming users with statically configured IP addresses. To support this special overlapping condition, all IP subscribers must be in a Layer 2 connected access network in which overlapping MAC addresses do not exist. In this case, IP subscribers can be distinguished using MAC addresses.
ISG Subscriber IP Address Assignment Using DHCP
When ISG is in the path of DHCP requests (as either a DHCP server or a DHCP relay), ISG can influence the IP address pool and DHCP server that are used to assign subscriber IP addresses. To enable ISG to influence the IP addresses assigned to subscribers, associate a DHCP address pool class with an address domain. The DHCP address pool class must also be configured in a service policy map, service profile, or user profile that is associated with a subscriber. When a DHCP request is received from a subscriber, DHCP uses the address pool class that is associated with the subscriber to determine which DHCP address pool should be used to service the request. As a result, on a per-request basis, an IP address is provided by the local DHCP server or relayed to a remote DHCP server that is defined in the selected pool.
IP Subscriber Identity
IP subscriber identity is closely related to IP session initiation because ISG must uniquely identify an IP subscriber at the moment that it creates the IP session. However, the need to identify an IP subscriber goes beyond the session initiation phase. The following sections describe how ISG uniquely identifies IP subscribers:
•Routed IP Subscriber Identity
•MAC Address as Secondary Identity
•DHCP Lease Query Support
•Layer 2 Connected IP Subscriber Identity
Routed IP Subscriber Identity
If the access network is a routed network, subscriber IP addresses can be used to uniquely identify IP subscribers because by definition subscriber IP addresses are at least routable in the access network.
When using a subscriber IP address as the identifier, ISG assumes that the subscriber IP address is unique. If the access network is deployed with Layer 3 load balancing, redundancy, or asymmetric routing, ISG also assumes that IP traffic from the same IP subscriber may arrive at different access interfaces. To support this type of deployment, ISG assumes a single IP address space for all the access interfaces connecting to the same access network.
If there is a requirement to support several IP address spaces over a single physical access network, the access network must use some Layer 2 encapsulation to create a separate logical access network for each IP address space. In this case, ISG can still have a single IP address space for all the logical access interfaces that connect to a logical access network.
When subscriber IP addresses are private IP addresses, the access network must be able to route such subscriber traffic. If the subscriber traffic is destined to the Internet, NAT must be performed.
For routed IP subscribers, the subscriber IP address serves as the key for an IP session. ISG associates IP traffic with an IP session as follows:
•In the upstream direction, the source IP address of an IP packet is used to identify the IP session. The source IP address is the subscriber IP address.
•In the downstream direction, the destination IP address of an IP packet is used to identify the IP session. The destination IP address is the subscriber IP address.
If the IP subscriber is a VPN user, the subscriber IP address must be routable in both the global routing table and the VPN routing table on the ISG.
In the case of an IP subnet subscriber, a subscriber IP address is defined as an IP prefix address instead of a /32 IP host address. This IP prefix covers a range of IP addresses used by end users but represents a single logical IP subscriber from the ISG point of view. In this deployment, all end users share the same connectivity and services provided by the ISG.
To normalize the classification of IP subscribers that have different network masks, ISG uses the network mask in conjunction with the subscriber IP address for routed IP subscribers.
MAC Address as Secondary Identity
You must configure the collect identifier mac-address command at the start of a session. This instructs the ISG devices to store the MAC address as part of the session identifiers. For routed IP subscriber sessions, the MAC address is collected from the DHCP server using the DHCP Lease Query Protocol. For information about configuring the command, see the "Configuring ISG Control Policies" module in the Cisco IOS ISG Configuration Guide.
DHCP Lease Query Support
The DHCP Lease Query message is a DHCP message type transmitted from a DHCP relay agent to a DHCP server. A DHCP Lease Query-aware relay agent sends the location of an IP endpoint to the DHCP Lease Query message.
The DHCP Lease Query transaction is a DHCP transaction with special message types that enable clients to query DHCP servers regarding the owner and the lease expiration time of an IP address. For information about configuring DHCP server for Lease Query, see the "Configuring a DHCP Server IP Address" section.
Layer 2 Connected IP Subscriber Identity
A Layer 2 connected access network is capable of providing IP connectivity to IP subscribers with foreign and overlapping IP addresses, in addition to IP subscribers with native IP addresses. Because subscriber IP addresses might not be unique in such an access network, ISG uses the subscriber MAC address to identify Layer 2 connected IP subscribers, regardless of what kind of IP address a subscriber has.
Traffic that comes from IP subscribers with private or overlapping IP addresses and that is destined to the Internet is subject to NAT.
For Layer 2 connected IP subscribers, both the subscriber MAC address (unique within a VLAN) and the IP address serve as the keys for the IP session, but they are used in different directions:
•In the upstream direction, the VLAN ID and source MAC address of an IP packet are used to identify the IP session.
•In the downstream direction, both the destination IP address and the VLAN ID of an IP packet are used to identify the IP subscriber context.
VPN Connectivity and Services for IP Subscribers
•Subscriber VPN Membership
•Multiservice Interface Model
•VPN Addressing
•VPN IP Subscriber Identity
•Service Model for VRF Transfers
•Benefits of Dynamic VPN Selection
Subscriber VPN Membership
Depending on deployment requirements, an IP subscriber may or may not have VPN service. If an IP subscriber does have VPN service, the subscriber may belong to only one VPN domain at any time. An IP subscriber is associated with a VPN domain in one of the following ways:
•Static VPN assignment—The VPN IP subscriber belongs to a static VPN domain. Whenever the IP subscriber connects to ISG, the IP subscriber is placed in the preassigned VPN domain.
•Dynamic VPN selection—The VPN IP subscriber can choose and switch among different VPN domains through dynamic service logon. Whenever a new VPN domain is selected, VPN services of the current VPN domain must be removed before VPN services of the new VPN domain can be applied to the IP subscriber.
Dynamic VPN selection can be initiated through automatic service logon, where the VRF is downloaded and applied to the subscriber session at session start, or through subscriber service selection at a web portal, in which case the subscriber is transferred to the VRF that corresponds to the selected service.
Multiservice Interface Model
For a subscriber without a static VPN configuration, a multiservice interface must be configured on the ISG device to map the IP session to a VRF. The multiservice interface represents a boundary between a VPN routing domain and the default routing domain. In cases where an IP subscriber may be associated with several routing domains throughout the duration of a connection, multiservice interfaces serve as demarcation points for the IP subscriber to switch from one VPN domain to another. One multiservice interface must be configured for each VPN routing domain. Figure 3 illustrates the multiservice interface model.
Figure 3 Multiservice Interface Model
VPN Addressing
When a subscriber session is transferred from one VPN domain to another, it is effectively entering a new addressing domain that may or may not overlap the subscriber's previous domain. The subscriber's network-facing address must be altered accordingly so that packets can be correctly routed back from within the service domain.
A VRF transfer is necessary when a subscriber's identity and subscribed services cannot be determined without interaction with a web portal. A local routing context is required, at least initially, so that IP packets may be routed to and from the portal server. Following portal-based service selection, the subscriber would typically have to be transferred into the VRF associated with the selected service domain. Following a VRF transfer, the subscriber must also receive an address that is routable in this new domain.
If ISG is adjacent to the subscriber device and serves as a DHCP relay or server, DHCP can be used to assign domain-specific addresses to subscribers.
In order for VRF transfers to be supported, it is strongly recommended that DHCP be configured with short initial leases, this is because existing subscriber addresses can only be altered once the current lease has expired. Subscribers will not have access to the selected domain before the next DHCP renew request is received. Using short initial lease times minimizes the interval between a VRF change and a DHCP renewal. If long lease times are used, an out-of-band method of initiating IP address change should be implemented.
When DHCP can be used to assign a new address at the subscriber device, subnet-based VRF selection can be used to bring about the transfer. Subnet-based VRF selection (also known as VRF autoclassify) is a feature that selects the VRF at the ingress port on the basis of the source IP subnet address.
Service providers and organizations have allocated public IP address blocks that are not overlapping by nature. Therefore, when they are assigned public IP addresses, VPN IP subscribers have no overlapping IP addresses. When VPN IP subscribers of different VPN domains have private IP addresses assigned, they are likely to have overlapping addresses in the access network.
An access network is a single IP address space when there is no Layer 2 encapsulation separating VPN IP subscribers of different VPN domains. Therefore, ISG must be able to handle overlapping IP addresses when deploying VPN IP subscribers. IP connectivity for VPN IP subscribers with overlapping IP addresses is possible only when they are connected to ISG through a Layer 2 connected access network.
VPN IP Subscriber Identity
ISG identifies VPN IP subscribers in the same way that it identifies non-VPN IP subscribers. Upstream IP traffic is defined as the subscriber IP traffic traveling from the access network to the VPN (overlaid on top of the service provider core network). Downstream IP traffic is defined as the subscriber IP traffic traveling from the VPN to the access network.
Service Model for VRF Transfers
A primary service is a service that contains a network-forwarding policy (such as a VRF) in its service definition. Only one primary service at a time can be activated for a session. A secondary service is any service that does not contain a network-forwarding policy.
When a subscriber for whom a primary service has already been activated tries to select another primary service, ISG will deactivate all current services (including the current primary service) and activate the new primary service, and hence switch the VRF.
When a subscriber for whom a primary service has already been activated tries to select a secondary service, the action taken by ISG depends on whether the secondary service is part of a service group. A service group is a grouping of services that may be simultaneously active for a given session. Typically, a service group includes one primary service and one or more secondary services. Table 1 describes the action that ISG will take when a subscriber selects a secondary service.
Table 1 ISG Activation Policy for Secondary Services
Primary Service Characteristics
|
Secondary Service Characteristics
|
Resulting Behavior at ISG
|
Primary service with no service group attribute |
Secondary service with service group |
Do not bring up the secondary service. |
Secondary service with no service group |
Bring up the secondary service. |
Primary service with service group attribute |
Secondary service with different service group |
Do not bring up the secondary service. |
Secondary service with same service group |
Bring up the secondary service. |
Secondary service with no service group |
Bring up the secondary service. |
Benefits of Dynamic VPN Selection
The need for switching of a subscriber session between routing and forwarding domains (also called network services) occurs frequently in markets where so-called equal access networking must be supported. Equal access networking is often mandated by regulatory rules stating that an access provider should allow service providers equal access to a retail subscriber network. ISG dynamic VPN selection facilitates equal access networking by allowing subscribers to transfer between network services.
IP Session Termination
An IP session may be terminated in one of the following ways:
•DHCP Lease Expiry or DHCP Release from client
If DHCP is used to detect a new session, its departure may also be signaled by a DHCP event.
•Application stop
An application command that is used to terminate a session. The application stop command is typically used to terminate a session when a subscriber initiates an account logoff from a web portal. An application stop may also result from the actions of an administrator, such as action taken in response to rogue behavior from a subscriber.
•Idle timeout and session timeout
Idle timeouts and session timeouts can be used to detect or impose termination of an IP session.
•Control policy
A control policy containing the "service disconnect" action can be used to terminate a session.
IP Session Recovery for DHCP-Initiated IP Sessions
When an IP session is terminated (for example, by account logoff or session timeout) or lost (for example, by router reload), the client may continue to hold an unexpired DHCP lease. When this happens, ISG performs a session restart to prevent the client's IP connection from being stuck until the DHCP lease expires. A control policy can be configured to define the actions that ISG will take when the session restart event occurs. If a policy is not defined, a default policy will take effect. The default policy causes ISG to disconnect the session after 60 seconds following a session restart and is the equivalent of the following configuration:
policy-map type control GLOBAL
class type control always event session-restart
1 service disconnect delay 60
This default policy appears in the output for the show subscriber policy rules command as follows:
Rule: internal-rule-session-restart
Class-map: always event session-restart
Action: 1 service disconnect delay 60
Default Services for IP Subscriber Sessions
Newly created IP sessions may require a default service to allow subsequent subscriber packets to be processed appropriately; for example, to permit or force TCP packets to a captive portal where menu-driven authentication and service selection can be performed. A default service policy map or service profile may be configured for IP sessions to redirect traffic, enable port-bundle host-key functionality for session identification, or enable transparent autologon. A default service would also likely include a network service, which allows subscribers to access a web portal for authentication and service selection.
How to Configure ISG for IP Subscriber Sessions
•Creating ISG Sessions for IP Subscribers (required)
•Assigning ISG Subscriber IP Addresses Using DHCP (required)
•Configuring ISG Dynamic VPN Selection (required)
Creating ISG Sessions for IP Subscribers
An ISG device creates IP sessions for IP traffic on subscriber-side interfaces. The following tasks enable IP sessions and indicate how sessions will be identified:
•Creating IP Subscriber Sessions for Routed ISG Subscribers (required)
•Creating IP Subscriber Sessions for Layer 2 Connected ISG Subscribers (required)
•Creating ISG IP Interface Sessions (required)
•Creating an ISG Static Session (required)
•Creating ISG IP Subnet Sessions (required)
•Configuring IP Session Recovery for DHCP-Initiated IP Sessions (required)
•Verifying ISG IP Subscriber Sessions (optional)
•Clearing ISG IP Subscriber Sessions (optional)
Creating IP Subscriber Sessions for Routed ISG Subscribers
Routed IP subscribers are subscribers that are routed through a Layer 3 access network with at least one transit router before reaching the ISG. Perform this task to configure ISG to create IP sessions for routed IP subscribers.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. ip subscriber routed
5. initiator {dhcp [class-aware] | radius-proxy | unclassified ip-address}
6. end
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type number
Router(config)# interface gigabitethernet 0/0/0 |
Specifies an interface and enters interface configuration mode. |
Step 4 |
ip subscriber routed
Router(config-if)# ip subscriber routed |
Specifies the type of IP subscriber to be hosted on the interface, and enters ISG IP subscriber configuration mode. |
Step 5 |
initiator {dhcp [class-aware] | radius-proxy | unclassified ip-address}
Router(config-subscriber)# initiator dhcp |
Configures ISG to create an IP subscriber session upon receipt of the specified packet type. •dhcp—ISG will initiate an IP session upon receipt of a DHCP DISCOVER packet. The class-aware keyword allows ISG to influence the IP address assigned by DHCP by providing DHCP with a class name. •radius-proxy—ISG will initiate an IP session upon receipt of a RADIUS Access-Request packet. •unclassified ip-address—ISG will initiate an IP session upon receipt of the first IP packet with an unclassified IP source address. •This command can be entered more than once to specify more than one method of IP session initiation. Note If the ISG device serves as either a DHCP relay or DHCP server in the assignment of client IP addresses, ISG must be configured to initiate IP sessions upon receipt of DHCP DISCOVER packets. In other words, the initiator dhcp command must be configured instead of the initiator unclassified ip or initiator unclassified mac command. |
Step 6 |
end
Router(config-subscriber)# end |
(Optional) Returns to privileged EXEC mode. |
Creating IP Subscriber Sessions for Layer 2 Connected ISG Subscribers
Layer 2 connected subscribers are either directly attached to the physical interfaces of an ISG or connected to an ISG through a Layer 2 access network, such as a bridged network or a switched network. Perform this task to configure ISG to create IP sessions for Layer 2 connected IP subscribers.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. ip subscriber l2-connected
5. initiator {dhcp [class-aware] | radius-proxy | unclassified mac-address}
6. end
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type number
Router(config)# interface gigabitethernet 0/0/0 |
Specifies an interface and enters interface configuration mode. |
Step 4 |
ip subscriber l2-connected
Router(config-if)# ip subscriber l2-connected |
Specifies the type of IP subscriber to be hosted on the interface, and enters ISG IP subscriber configuration mode. Note It is recommended that IP sessions for Layer 2 connected subscribers be configured using the ip subscriber l2-connected command. However, the ip subscriber routed command could also be used if subscriber IP addresses are routable in the access domain. |
Step 5 |
initiator {dhcp [class-aware] | radius-proxy | unclassified mac-address}
Router(config-subscriber)# initiator unclassified mac-address |
Configures ISG to create an IP subscriber session upon receipt of the specified packet type. •dhcp—ISG initiates an IP session upon receipt of a DHCP DISCOVER packet. The class-aware keyword allows ISG to influence the IP address assigned by DHCP by providing DHCP with a class name. •radius-proxy—ISG initiates an IP session upon receipt of a RADIUS packet. •unclassified mac-address—ISG will initiate an IP session upon receipt of the first IP packet with an unclassified MAC source address. •This command can be entered more than once to specify more than one method of IP session initiation. Note If the ISG device serves as either a DHCP relay or DHCP server in the assignment of client IP addresses, ISG must be configured to initiate IP sessions upon receipt of DHCP DISCOVER packets. In other words, the initiator dhcp command must be configured instead of the initiator unclassified ip or initiator unclassified mac command. |
Step 6 |
end
Router(config-subscriber)# end |
(Optional) Returns to privileged EXEC mode. |
Creating ISG IP Interface Sessions
An ISG IP interface session encompasses all IP packets that cross the specified interface or subinterface. Perform this task to create an ISG IP interface session.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number[.subinterface-number]
4. ip subscriber interface
5. end
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type number[.subinterface-number]
Router(config)# interface GigabitEthernet 0//0/0.1 |
Specifies an interface or subinterface and enters interface configuration mode. |
Step 4 |
ip subscriber interface
Router(config-subif)# ip subscriber interface |
Specifies the type of IP subscriber to be hosted on the interface. |
Step 5 |
end
Router(config-subif)# exit |
(Optional) Returns to privileged EXEC mode. |
Creating an ISG Static Session
The ISG Static Session Creation feature enables administrator initiated static IP sessions. An ISG static session enables you to configure static IP sessions from the CLI. You can create static IP sessions by configuring a group of server addresses.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip subscriber list list-name
4. ip source ipaddress mac macaddress
or
ip source ipaddress mask subnetmask
5. exit
6. interface type number
7. ip subscriber l2-connected
or
ip subscriber routed
8. initiator static ip subscriber list list-name
9. end
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
ip subscriber list list-name
Router(config)# ip subscriber list mylist |
Specifies the IP subscriber list name and enters server list configuration mode. |
Step 4 |
ip source ipaddress mac macaddress or ip source ipaddress mask subnetmask
Router(config-server-list)# ip source 209.165.200.225 mac 0.7.f or Router(config-server-list)# ip source 209.165.200.225 mask 255.255.255.224 |
Specifies the static server IP address and MAC address (in the case of Layer 2-connected) or subnet mask (in the case of routed). |
Step 5 |
exit
Router(config-server-list)# exit |
Returns to global configuration mode. |
Step 6 |
interface type number
Router(config)# interface GigabitEthernet 2/0/0 |
Specifies an interface and enters interface configuration mode. |
Step 7 |
ip subscriber l2-connected or ip subscriber routed
Router(config-if)# ip subscriber l2-connected or Router(config-if)# ip subscriber routed |
Specifies the type of IP subscriber to be hosted on the interface and enters ISG IP subscriber configuration mode. Note It is recommended that IP sessions for Layer 2 connected subscribers be configured using the ip subscriber l2-connected command. However, the ip subscriber routed command could also be used if subscriber IP addresses are routable in the access domain. |
Step 8 |
initiator static ip subscriber list list-name
Router(config-subscriber)# initiator static ip subscriber list mylist |
Creates an IP subscriber session with the packet type as static and attaches the session to the list. |
Step 9 |
end
Router(config-subscriber)# end |
Returns to privileged EXEC mode. |
Creating ISG IP Subnet Sessions
An IP subnet session represents all the traffic that is associated with a single IP subnet. IP subnet sessions are used to apply uniform edge processing to packets associated with a particular IP subnet. When an IP subnet session is configured, ISG treats the subnet as a single subscriber, which means that ISG features and functionality are applied to the subnet traffic as an aggregate. Perform this task to configure an IP subnet session.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. ip subscriber routed
5. initiator unclassified ip-address
6. end
7. Add the Framed-IP-Netmask attribute to the service or user profile.
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type number
Router(config)# interface gigabitethernet 0/0/0 |
Specifies an interface and enters interface configuration mode. |
Step 4 |
ip subscriber routed
Router(config-if)# ip subscriber routed |
Specifies the type of IP subscriber to be hosted on the interface, and enters ISG IP subscriber configuration mode. |
Step 5 |
initiator unclassified ip-address
Router(config-subscriber)# initiator unclassified ip-address |
Configures ISG to create an IP subscriber session upon receipt of an IP packet with an unclassified IP source address. |
Step 6 |
end
Router(config-subscriber)# end |
(Optional) Returns to privileged EXEC mode. |
Step 7 |
Add the Framed-IP-Netmask attribute to the service or user profile. |
Enables an IP subnet session for the subscriber. •When a subscriber is authorized or authenticated and the Framed-IP-Netmask attribute is present in the user or service profile, ISG converts the source-IP-based session into a subnet session with the subnet value in the Framed-IP-Netmask attribute. |
Configuring IP Session Recovery for DHCP-Initiated IP Sessions
Perform this task to configure ISG to perform specific actions upon recovery of an IP session after ISG has terminated the session or reloaded. This task applies to DHCP-initiated IP sessions only.
If a policy for session recovery is not configured, ISG will apply the following default policy:
policy-map type control GLOBAL
class type control always event session-restart
1 service disconnect delay 60
SUMMARY STEPS
1. enable
2. configure terminal
3. policy-map type control policy-map-name
4. class type control {control-class-name | always} event session-restart
5. action-number authorize [aaa list list-name] [password password] [upon network-service-found {continue | stop}] identifier {authenticated-domain | authenticated-username | auto-detect | circuit-id [plus remote-id] | dnis | mac-address | nas-port | remote-id [plus circuit-id] | source-ip-address | tunnel-name | unauthenticated-domain | unauthenticated-username}
6. action-number service-policy type service [unapply] [aaa list list-name] {name service-name | identifier {authenticated-domain | authenticated-username | dnis | nas-port | tunnel-name | unauthenticated-domain | unauthenticated-username}}
7. action-number set-timer name-of-timer minutes
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
policy-map type control policy-map-name
Router(config)# policy-map type control MY-POLICY |
Creates or modifies a control policy map, which is used to define a control policy, and enters control policy-map configuration mode. |
Step 4 |
class type control {control-class-name | always} event session-restart
Router(config-control-policymap)# class type control always event session-restart |
Specifies a control class that will be evaluated when the session-restart event occurs and enters policy map class control configuration mode. •A policy rule for which the control class is always will always be treated as the lowest priority rule within the control policy map. |
Step 5 |
action-number authorize [aaa list list-name] [password password] [upon network-service-found {continue | stop}] identifier {authenticated-domain | authenticated-username | auto-detect | circuit-id [plus remote-id] | dnis | mac-address | nas-port | remote-id [plus circuit-id] | source-ip-address | tunnel-name | unauthenticated-domain | unauthenticated-username}
Router(config-control-policymap-class-control)# 1 authorize identifier source-ip-address |
(Optional) Initiates a request for authorization on the basis of the specified identifier. |
Step 6 |
action-number service-policy type service [unapply] [aaa list list-name] {name service-name | identifier {authenticated-domain | authenticated-username | dnis | nas-port | tunnel-name | unauthenticated-domain | unauthenticated-username}}
Router(config-control-policymap-class-control)# 1 service-policy type service aaa list LISTA name REDIRECT |
(Optional) Activates an ISG service. •Specifying an identifier instead of a service name will activate a service that has the same name as the specified identifier. |
Step 7 |
action-number set-timer name-of-timer minutes
Router(config-control-policymap-class-control)# 1 set-timer TIMERA 5 |
(Optional) Starts a named policy timer. •Expiration of the timer generates the event timed-policy-expiry. |
Verifying ISG IP Subscriber Sessions
Perform this task to verify IP subscriber session configuration and creation. The commands can be used in any order.
SUMMARY STEPS
1. enable
2. show subscriber session [detailed] [identifier identifier | uid session-id | username name]
3. show ip subscriber [dangling seconds | detail | ip ip-address | mac mac-address | vrf vrf-name static list listname [dangling seconds | detail | ip ip-address]]
4. exit
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
show subscriber session [detailed] [identifier identifier | uid session-id | username name]
Router# show subscriber session detailed |
Displays information about ISG policies and features for subscriber sessions. |
Step 3 |
show ip subscriber [dangling seconds | detail | ip ip-address | mac mac-address | vrf vrf-name | static list listname [dangling seconds | detail | ip ip-address]]
Router# show ip subscriber ip 10.10.10.10 |
Displays information about ISG IP subscriber sessions. •Use this command to display the IP sessions on ISG. |
Step 4 |
exit
Router# exit |
Exits privileged EXEC mode. |
Clearing ISG IP Subscriber Sessions
Perform this task to clear IP subscriber sessions.
SUMMARY STEPS
1. show ip subscriber [dangling seconds | detail | ip ip-address | mac mac-address | vrf vrf-name [dangling seconds | detail | ip ip-address]]
2. clear ip subscriber [dangling seconds | ip ip-address | mac mac-address | vrf vrf-name [dangling seconds | ip ip-address]]
DETAILED STEPS
|
|
|
Step 1 |
show ip subscriber [dangling seconds | detail | ip ip-address | mac mac-address | vrf vrf-name [dangling seconds | detail | ip ip-address]]
Router# show ip subscriber ip 10.10.10.10 |
(Optional) Displays information about ISG subscriber IP sessions. •Use this command to display the IP sessions on ISG. |
Step 2 |
clear ip subscriber [dangling seconds | ip ip-address | mac mac-address | vrf vrf-name [dangling seconds | ip ip-address]]
Router# clear ip subscriber ip 10.10.10.10 |
Clears ISG IP subscriber sessions. |
Troubleshooting Tips
Use the following commands to troubleshoot ISG IP subscriber sessions:
•debug ip subscriber
•debug condition
Assigning ISG Subscriber IP Addresses Using DHCP
•Configuring an ISG Interface for Dynamic DHCP Class Association (required)
•Configuring DHCP Server User Authentication (required)
•Configuring a DHCP Class in a Service Policy Map (required)
•Configuring a DHCP Class in a Service Profile or User Profile on the AAA Server (required)
Prerequisites
For ISG to use DHCP to assign IP addresses, the following prerequisites must be met:
•The subscriber must be Layer 2 connected.
•ISG must be in the path of DHCP requests, serving as a DHCP server or relay.
•The appropriate IP subnets must be configured on the subscriber interface.
The tasks in this section assume that you have configured DHCP support in your network.
Configuring an ISG Interface for Dynamic DHCP Class Association
Perform this task to enable ISG to influence the assignment of IP addresses to subscribers on the interface by providing the local DHCP component with a class name. The class name refers to a class configured using the ip dhcp pool command and can reference a pool of addresses or a relay destination.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. ip address ip-address mask [secondary]
5. ip subscriber [l2-connected | routed]
6. initiator dhcp class-aware
7. end
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type number
Router(config)# interface gigabitethernet 0/0/0 |
Specifies an interface for configuration, and enters interface configuration mode. |
Step 4 |
ip address ip-address mask [secondary]
Router(config-if)# ip address 10.1.0.1 255.255.0.0 |
Sets a primary or secondary IP address for an interface. |
Step 5 |
ip subscriber [l2-connected | routed]
Router(config-if)# ip subscriber |
Enables ISG IP subscriber configuration mode. |
Step 6 |
initiator dhcp class-aware
Router(config-if) initiator dhcp class-aware |
Configures ISG to create IP sessions upon receipt of DHCP DISCOVER packets. •The class-aware keyword allows ISG to influence the IP address assigned by DHCP by providing DHCP with a class name. |
Step 7 |
end
Router(config-if)# end |
(Optional) Returns to privileged EXEC mode. |
Configuring DHCP Server User Authentication
Perform this task to authenticate the DHCP clients on the server.
Prerequisites
You need to use the ISG framework to enable DHCP server user authentication.
SUMMARY STEPS
1. enable
2. configure terminal
3. aaa new-model
4. aaa authentication login list-name local
5. ip dhcp pool pool-name
6. network network-number mask
7. exit
8. interface type number
9. ip subscriber l2-connected
10. initiator dhcp class-aware
11. end
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
aaa new-model
Router(config)# aaa new model |
Enables authentication, authorization, and accounting (AAA). |
Step 4 |
aaa authentication login list-name local
Router(config)# aaa authentication login mylist local |
Sets the AAA authentication at login. |
Step 5 |
ip dhcp pool pool-name
Router(config)# ip dhcp pool testpool |
Creates a name for the DHCP server address pool and enters DHCP pool configuration mode. |
Step 6 |
network network-number mask
Router(dhcp-config)# network 172.16.0.0 255.240.0.0 |
Configures the network number and mask for a DHCP address pool primary or secondary subnet on a Cisco IOS DHCP server. |
Step 7 |
exit
Router(dhcp-config)# exit |
Returns to global configuration mode. |
Step 8 |
interface type number
Router(config)# interface Ethernet 0/0 |
Enters interface configuration mode. |
Step 9 |
ip subscriber l2-connected
Router(config-if)# ip subscriber l2-connected |
Configures a Layer 2 connected IP session on the interface and enters IP subscriber configuration mode. |
Step 10 |
initiator dhcp class-aware
Router(config-subscriber)# initiator dhcp class-aware |
Initiates a class for DHCP for an IP session initiated by DHCP. |
Step 11 |
end
Router(config-subscriber)# end |
Returns to privileged EXEC mode. |
Troubleshooting Tips
You can determine the DHCP authentication by using the debug ip dhcp server events, debug ip dhcp server packet, and debug subscriber policy dpm event commands. The following is sample output from the debug subscriber policy dpm event command:
*Apr 20 20:20:03.510: SG-DPM: DHCP Discover notification from client, mac_address =
001a.7014.c03e
*Apr 20 20:20:03.510: SG-DPM: getting the context for mac_address = 001a.7014.c03e
*Apr 20 20:20:03.510: SG-DPM: Could not find a dhcp_context for 001a.7014.c03e:
*Apr 20 20:20:03.510: SG-DPM: Sending an ID manager request with key as 001a.7014.c03e
*Apr 20 20:20:03.510: SG-DPM: Received reply from Id manager
*Apr 20 20:20:03.510: SG-DPM: Session Initiation notification on Active
*Apr 20 20:20:03.510: SG-DPM: Allocated SHDB Handle (0xB6000252) for Mac address
001a.7014.c03e
*Apr 20 20:20:03.510: SG-DPM: Client is able to perform DHCP Authentication.Setting the
SSS_INFOTYPE_DHCP_AUTH_KEY
*Apr 20 20:20:03.510: SG-DPM: Sending Session start to PM, mac_address = 001a.7014.c03e
*Apr 20 20:20:03.514: SG-DPM: Request for Classname from client, mac_address =
001a.7014.c03e
*Apr 20 20:20:03.514: SG-DPM: getting the context for mac_address = 001a.7014.c03e
*Apr 20 20:20:03.514: SG-DPM: Sending an ID manager request with key as 001a.7014.c03e
*Apr 20 20:20:03.514: SG-DPM: Received reply from Id manager
*Apr 20 20:20:03.514: SG-DPM: No session found in ID manager
*Apr 20 20:20:03.514: SG-DPM: Processing sg_dpm_get_more_keys from SSS hdl 56000E52
*Apr 20 20:20:03.514: SG-DPM: DPM is providing Auth-User
You can also use the show subscriber session detailed and show ip dhcp binding commands to display subscriber information and DHCP pool information. The following is sample output from the show ip dhcp binding command:
Router# show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address Client-ID/ Lease expiration Type
10.0.0.1 0100.1a70.1530.38 Nov 18 2008 03:43 PM Automatic
Configuring a DHCP Class in a Service Policy Map
Perform this task to assign a DHCP class to a service policy map. Subscribers for which this service policy map is activated will be assigned IP addresses from the DHCP pool or the remote server that is associated with the class.
Prerequisites
A DHCP pool must be configured. Classes configured within the DHCP pool must match the DHCP classes configured in the service policy map.
SUMMARY STEPS
1. enable
2. configure terminal
3. policy-map type service policy-name
4. classname class-name
5. end
6. show policy-map type service
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
policy-map type service policy-name
Router(config)# policy-map type service service1 |
Creates a service policy map or specifies an existing service policy map for configuration, and enters service policy-map configuration mode. |
Step 4 |
classname class-name
Router(config-service-policymap)# classname class1 |
Associates a DHCP pool with a service policy map. |
Step 5 |
end
Router(config-service-policymap)# end |
(Optional) Returns to privileged EXEC mode. |
Step 6 |
show policy-map type service
Router# show policy-map type service |
(Optional) Displays the contents of all service policy maps. •Use this command to verify that the DHCP class is associated with the service policy map. |
What to Do Next
Once you have configured the DHCP address pool class in a service policy map, 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 a DHCP Class in a Service Profile or User Profile on the AAA Server
Perform this task to add the vendor-specific attribute (VSA) for a DHCP class to a user profile or service profile on the AAA server. Subscribers for whom the user or service profile is activated will be assigned IP addresses from the DHCP pool or the remote server that is associated with the class.
Prerequisites
A DHCP address pool must be configured. Classes configured within the DHCP address pool must match the DHCP address pool classes configured in the service or user profile.
SUMMARY STEPS
1. Add the DHCP Class attribute to the user or service profile.
DETAILED STEPS
|
|
|
Step 1 |
Add the DHCP Class attribute to the user or service profile.
26,9,1 = "subscriber:classname=class-name" |
Associates a DHCP address pool with a service or specific subscriber. |
What to Do Next
You may want to configure a method of activating the service policy map or service profile; 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 a DHCP Server IP Address
Perform this task to specify which DHCP servers to use on your network, or to configure the IP address of one or more DHCP servers available on the network, and to specify the DHCP Lease Query for routed IP sessions.
Note The DHCP server IP address needs to be configured for routed IP sessions, if the DHCP Lease Query is performed.
Prerequisites
•The DHCP server must support the DHCP lease protocol.
•The IP address of the phone must be assigned by DHCP address assignments.
•The traffic must be classified as Layer 3.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip dhcp-server {ip-address | query lease {retries max-retransmissions | timeout timeout-query-seconds}
4. end
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
ip dhcp-server {ip-address | query lease {retries max-retransmissions | timeout timeout-query-seconds}}
Router(config)# ip dhcp-server query lease retries 3 |
Configures the IP address of one or more DHCP servers available on the network, and specifies the DHCP Lease Query for routed IP sessions. |
Step 4 |
end
Router(config)# end |
Exits global configuration mode. |
Configuring ISG Dynamic VPN Selection
•Configuring a Multiservice Interface (required)
•Specifying a VRF in a Service Policy Map (required)
•Verifying VRF Transfer for IP Sessions (optional)
•Troubleshooting VRF Transfer for IP Sessions (optional)
Configuring a Multiservice Interface
Perform the steps in this procedure to configure a multiservice interface.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface multiservice interface-number
4. ip vrf forwarding vrf-name
5. ip address ip-address mask
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface multiservice interface-number
Router(config)# interface multiservice 1 |
Creates a multiservice interface, which enables dynamic VPN selection and enters interface configuration mode. |
Step 4 |
ip vrf forwarding vrf-name
Router(config-if)# ip vrf forwarding vrf1 |
Associates a VPN VRF with an interface or subinterface. |
Step 5 |
ip address ip-address mask
Router(config-if)# ip address 209.165.200.223 255.255.255.0 |
Sets the primary IP address for an interface. •Specify the IP address of the VPN. |
Specifying a VRF in a Service Policy Map
VRF transfer occurs when a new primary service is activated for a session, causing the session to transfer from one VRF to another. Services can be configured in service profiles on an external authentication, authorization, and accounting (AAA) server or they can be configured on the ISG device in service policy maps. Perform this task to configure a VRF in a service policy map on the ISG device.
SUMMARY STEPS
1. enable
2. configure terminal
3. policy-map type service policy-map-name
4. ip vrf forwarding name-of-vrf
5. sg-service-type primary
6. sg-service-group service-group-name
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
policy-map type service policy-map-name
Router(config)# policy-map type service service1 |
Creates or modifies a service policy map, which is used to define an ISG service, and enters service policy-map configuration mode. |
Step 4 |
ip vrf forwarding name-of-vrf
Router(config-service-policymap)# ip vrf forwarding vrf2 |
Associates the service with a VRF. |
Step 5 |
sg-service-type primary
Router(config-service-policymap)# sg-service-type primary |
Defines the service as a primary service. •A primary service is a service that contains a network-forwarding policy. A primary service must be defined as a primary service by using the sg-service-type primary command. Any service that is not a primary service is defined as a secondary service by default. |
Step 6 |
sg-service-group service-group-name
Router(config-service-policymap)# sg-service-group group1 |
(Optional) Associates an ISG service with a service group. •A service group is a grouping of services that may be active simultaneously for a given session. Typically, a service group includes one primary service and one or more secondary services. |
Verifying VRF Transfer for IP Sessions
Perform the steps in the following task as needed to verify VRF transfer for IP sessions.
SUMMARY STEPS
1. enable
2. show subscriber session uid session-identifier detail
3. show ip subscriber [dangling seconds | detail | ip ip-address | mac mac-address | vrf vrf-name [dangling seconds | detail | ip ip-address]]
4. show idmgr {memory [detailed [component [substring]]] | service key session-handle session-handle-string service-key key-value | session key {aaa-unique-id aaa-unique-id-string | domainip-vrf ip-address ip-address vrf-id vrf-id | nativeip-vrf ip-address ip-address vrf-id vrf-id | portbundle ip ip-address bundle bundle-number | session-guid session-guid | session-handle session-handle-string | session-id session-id-string} | statistics}
5. show ip route [vrf vrf-name]
6. show ip dhcp binding [ip-address]
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
show subscriber session uid session-identifier detail
Router# show subscriber session uid 4 detail |
Displays information about ISG subscriber sessions with a specific session identifier. |
Step 3 |
show ip subscriber [dangling seconds | detail | ip ip-address | mac mac-address | vrf vrf-name [dangling seconds | detail | ip ip-address]]
Router# show ip subscriber vrf vrf3 |
Displays information about ISG IP subscriber sessions. |
Step 4 |
show idmgr {memory [detailed [component [substring]]] | service key session-handle session-handle-string service-key key-value | session key {aaa-unique-id aaa-unique-id-string | domainip-vrf ip-address ip-address vrf-id vrf-id | nativeip-vrf ip-address ip-address vrf-id vrf-id | portbundle ip ip-address bundle bundle-number | session-guid session-guid | session-handle session-handle-string | session-id session-id-string} | statistics}
Router# show idmgr session key nativeip-vrf ip-address 10.0.0.1 |
Displays information related to ISG session and service identity. |
Step 5 |
show ip route [vrf vrf-name]
Router# show ip route |
Displays the current state of the routing table. |
Step 6 |
show ip dhcp binding [ip-address]
Router# show ip dhcp binding |
Displays address bindings on the Cisco IOS DHCP server. |
Troubleshooting VRF Transfer for IP Sessions
The commands in this procedure can be used to troubleshoot VRF transfer for IP sessions. These commands can be entered in any order.
SUMMARY STEPS
1. debug subscriber {event | error | packet | policy | service}
2. debug ip subscriber {event | error | packet | fsm | all}
3. debug subscriber policy dpm {error | event}
4. debug ip dhcp server {events | packets | linkage | class}
DETAILED STEPS
|
|
|
Step 1 |
debug subscriber {event | error | packet | policy | service}
Router# debug subscriber service |
Displays debugging messages pertaining to subscriber policies, policy server events, and changes to service. |
Step 2 |
debug ip subscriber {event | error | packet | fsm | all}
Router# debug ip subscriber error |
Displays debugging messages pertaining to an IP session created on the service gateway. |
Step 3 |
debug subscriber policy dpm {error | event}
Router# debug subscriber policy dpm event |
Displays diagnostic information about policy execution that is related to DHCP events. |
Step 4 |
debug ip dhcp server {events | packets | linkage | class}
Router# debug dhcp ip dhcp server events |
Enables Cisco IOS DHCP server debugging. |
Configuration Examples for ISG Access for IP Subscriber Sessions
•Example: ISG IP Interface Subscriber
•Example: ISG Routed IP Subscriber
•Example: ISG Layer 2 Connected IP Subscriber
•Example: DHCP-Initiated Session Recovery
•Example: ISG Interface with DHCP Class-Aware Capability
•Example: DHCP Address Pool Classes and Relay Actions for ISG
•Example: Dynamic VPN Selection
Example: ISG IP Interface Subscriber
The following example shows how to configure an IP interface session on GigabitEthernet interface 0/0/1.401:
interface GigabitEthernet 0/0/1.401
Example: ISG Routed IP Subscriber
The following example shows how to configure ISG to create IP sessions for subscribers who connect to ISG on GigabitEthernet interface 0/0/1.401 through a routed access network. ISG will create IP sessions upon receipt of DHCP DISCOVER packets, incoming valid IP packets, and RADIUS Access-Request packets.
interface GigabitEthernet0/0/1.401
initiator dhcp class-aware
initiator unclassified ip-address
Example: ISG Layer 2 Connected IP Subscriber
The following example shows how to configure ISG to create IP sessions for subscribers who connect to ISG on GigabitEthernet interface0/0/1.401 through a Layer 2 connected access network. ISG will create IP sessions upon receipt of any frame with a valid source MAC address.
interface GigabitEthernet0/0/1.401
ip subscriber l2-connected
initiator unclassified mac-address
Example: ISG Static Session Creation
The following example shows how to create an ISG static session for server 209.165.200.225 for subscribers who connect to ISG on GigabitEthernet interface 0/4 through a Layer 2 connected access network. ISG will create a static session upon receipt of valid source IP address.
ip subscriber list mylist
ip source 209.165.200.225 mac 0.7.f
interface GigabitEthernet 2/0/0
ip subscriber l2-connected
initiator static ip subscriber list mylist
Example: DHCP-Initiated Session Recovery
The following example configures an ISG policy that applies a service called "FIRST-SERVICE" upon session restart for subscribers belonging to the VRF "FIRST":
class-map type control TEST
policy-map type control GLOBAL
class type control TEST event session-restart
1 service-policy type service name FIRST-SERVICE
Example: ISG Interface with DHCP Class-Aware Capability
In the following example, GigabitEthernet interface 1/0/0.400 is configured with DHCP class-aware functionality, which enables ISG to influence DHCP IP address assignment. If the service "SERVICE_DHCP" is activated, the DHCP pool "DHCP_POOL2" is used for address assignment. Otherwise, the default pool "DHCP_POOL1" is used.
interface GigabitEthernet1/0/0.400
ip address 10.1.15.1 255.255.255.0 secondary
ip address 10.1.10.1 255.255.255.0
service-policy type control RULE_406a
ip subscriber l2-connected
initiator dhcp class-aware
ip dhcp excluded-address 10.1.10.1
network 10.1.10.0 255.255.255.0
network 10.1.15.0 255.255.255.0
ip dhcp class DHCP_CLASS2
policy-map type service SERVICE_DHCP
Example: DHCP Address Pool Classes and Relay Actions for ISG
This section contains examples of DHCP address pool configuration and relay actions for ISG.
DHCP Server Coresident with ISG Configuration
In the following configuration example, the ISPs are ISP1 and ISP2 companies. The ISP1 company has its addresses assigned from an address pool that is dynamically allocated using on-demand address pools (ODAP). The ISP2 company has its customer addresses assigned from the address pool 10.100.0.0/16. Customers not associated with any ISP will have an address allocated from the address pool 10.1.0.0/16, and the lease time is set to 10 minutes.
!Address pool for ISP1 customers
!Address pool for ISP2 customers
network 10.100.0.0 255.255.0.0
!Address pool for customers without an ISP
network 10.1.0.0 255.255.0.0
DHCP Relay Agent Coresident with ISG Configuration
In the following configuration example, there are two ISPs, "poolA" and "poolB". The "poolA" ISP and its customers are allowed to have addresses in the ranges 10.1.0.0/16 and 10.3.0.0/16, and are relayed to the DHCP server at 10.55.10.1. The "poolB" ISP and its customers are allowed to have addresses in the range 10.2.0.0/16 and 10.4.0.0/16, and are relayed to the DHCP server at 10.10.2.1.
interface gigabitethernet1/0/0
ip address 10.1.0.0 255.255.0.0
ip address 10.2.0.0 255.255.0.0 secondary
interface gigabitethernet2/0/0
ip address 10.3.0.0 255.255.0.0
ip address 10.4.0.0 255.255.0.0
!Address pools for poolA1 and poolB2:
relay source 10.1.0.0 255.255.0.0
!Address pool for poolA2:
relay source 10.3.0.0 255.255.0.0
!Address pools for poolB1 and poolB2:
relay source 10.2.0.0 255.255.0.0
relay source 10.4.0.0 255.255.0.0
Configuration of secure ARP for the relay will use the same configuration command as secure ARP already uses on a DHCP server by using the update arp command in address-pool configuration mode. If the system is allocating an address from this address pool, it will add secure ARP. If the system is relaying a packet using this address pool, it will also add secure ARP.
Example: Dynamic VPN Selection
The following example shows how to configure dynamic VPN selection using a multiservice interface:
network 10.0.0.1 255.255.0.0
ip dhcp class vrf-class-vrf1
policy-map type control TAL
class type control always event session-start
1 service-policy type service name pbhk
2 authorize identifier mac-address
interface GigabitEthernet0/0/7
ip address 10.1.1.0 255.255.0.0
service-policy type control TAL
ip subscriber l2-connected
initiator dhcp class-aware
Additional References
Related Documents
Standards
MIBs
|
|
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
Technical Assistance
|
|
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 ISG Access for IP Subscriber Sessions
Table 2 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 2 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.
Table 2 Feature Information for ISG Access for IP Subscriber Sessions
|
|
Feature Configuration Information
|
DHCP—Server User Authentication |
Cisco IOS XE Release 3.1S |
The DHCP Server User Authentication feature is used to authenticate the DHCP clients. The following section provides information about this feature: •Configuring DHCP Server User Authentication The following commands were introduced or modified by this feature: aaa authentication login, network (DHCP). |
IP Session Recovery for DHCP-Initiated IP Sessions |
Cisco IOS XE Release 2.2 |
ISG provides a default policy and the ability to configure a policy that determines the actions ISG will take upon session restart following the recovery of a DHCP-initiated IP session. The following sections provide information about this feature: •IP Session Recovery for DHCP-Initiated IP Sessions •Configuring IP Session Recovery for DHCP-Initiated IP Sessions The following commands were introduced or modified by this feature: class type control, match vrf. |
IP Subscriber Session CLI Updates |
Cisco IOS XE Release 2.2 |
Some of the commands that are used to configure ISG IP subscriber sessions were modified or replaced. The following section provides information about this feature: •How to Configure ISG for IP Subscriber Sessions The following commands were introduced or modified by this feature: clear ip subscriber, debug ip subscriber, identifier interface, identifier ip src-addr, initiator, interface multiservice, ip subscriber interface, ip subscriber, show ip subscriber. |
ISG: Instrumentation: DHCP Lease Query Support |
Cisco IOS XE Release 2.5.0 |
The DHCP Lease Query transaction is a DHCP transaction with special message types that enable, among other things, clients to query DHCP servers regarding the owner and the lease expiration time of an IP address. The following sections provide more information about this feature: •IP Subscriber Identity •Configuring a DHCP Server IP Address The following commands were introduced or modified: ip dhcp-server, collect identifier. |
ISG: Policy Control: DHCP Proxy |
Cisco IOS XE Release 2.2 |
This feature enables ISG to dynamically interact with DHCP and apply policies that influence the IP addresses that DHCP assigns subscribers. The following section provides information about this feature: •Assigning ISG Subscriber IP Addresses Using DHCP |
ISG: Session: Creation: Interface IP Session: L2 |
Cisco IOS XE Release 2.5.0 |
ISG IP interface sessions include all IP traffic received on a specific physical or virtual interface. IP interface sessions are provisioned through the CLI; that is, a session is created when the IP interface session commands are entered. The following sections provide information about this feature: •Information About ISG Access for IP Subscriber Sessions •Creating ISG IP Interface Sessions |
ISG: Session: Creation: Interface IP Session: L3 |
Cisco IOS XE Release 2.5.0 |
ISG IP interface sessions include all IP traffic received on a specific physical or virtual interface. IP interface sessions are provisioned through the CLI; that is, a session is created when the IP interface session commands are entered. The following sections provide information about this feature: •Information About ISG Access for IP Subscriber Sessions •Creating ISG IP Interface Sessions |
ISG: Session: Creation: IP Session: Protocol Event (DHCP) |
Cisco IOS XE Release 2.2 |
Most ISG sessions are created upon detection of a data flow that cannot be affiliated with an already active session. An ISG can be configured to create an IP session upon receipt of the first DHCP DISCOVER packet received from a subscriber. The following sections provide information about this feature: •Information About ISG Access for IP Subscriber Sessions •How to Configure ISG for IP Subscriber Sessions |
ISG: Session: Creation: IP Session: Subnet and Source IP: L2 |
Cisco IOS XE Release 2.2 |
The ISG session is the primary component used for associating services and policies across specific data flows. An IP subnet session is an ISG session that includes any IP traffic from a single IP subnet. A source-IP-based session includes traffic from a single source IP address. The following sections provide information about this feature: •Information About ISG Access for IP Subscriber Sessions •How to Configure ISG for IP Subscriber Sessions |
ISG: Session: Creation: IP Session: Subnet and Source IP: L3 |
Cisco IOS XE Release 2.2 |
The ISG session is the primary component used for associating services and policies across specific data flows. An IP subnet session is an ISG session that includes any IP traffic from a single IP subnet. A source-IP-based session includes traffic from a single source IP address. The following sections provide information about this feature: •Information About ISG Access for IP Subscriber Sessions •How to Configure ISG for IP Subscriber Sessions |
ISG: Session: Multicast: Coexistence |
Cisco IOS XE Release 2.5.0 |
The ISG Session Multicast Coexistence feature introduces the ability to host all the subscribers and services (data and multicast) on the same VLAN by enabling multicast and IP sessions to coexist on the same subinterface for Cisco ASR 10000 Series Aggregation Routers. The following sections provide information about this feature: •Coexistence of Multicast and IP Sessions •Creating IP Subscriber Sessions for Routed ISG Subscribers •Creating IP Subscriber Sessions for Layer 2 Connected ISG Subscribers •Creating ISG IP Subnet Sessions •Configuring an ISG Interface for Dynamic DHCP Class Association |
ISG: Session: VRF Transfer: |
Cisco IOS XE Release 2.2 |
The ISG session is the primary component used for associating services and policies with specific data flows. ISG sessions are associated with virtual routing and forwarding instances when routing is required for the network service. ISG VRF transfer provides a means to dynamically switch an active session between virtual routing domains. The following sections provide information about this feature: •Information About ISG Access for IP Subscriber Sessions •How to Configure ISG for IP Subscriber Sessions |
ISG: Static Session Creation |
Cisco IOS XE Release 2.5.0 |
The ISG Static Session Creation feature enables administrator initiated static IP sessions. The following section provides information about this feature: •Creating an ISG Static Session The following commands were introduced or modified by this feature: initiator static subscriber list, ip source, ip subscriber list, show ip subscriber list. |
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.
© 2006-2011 Cisco Systems, Inc. All rights reserved.