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IP Mobility: Mobile IP Configuration Guide, Cisco IOS Release 15M&T
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Mobile IP Generic NAI Support and Home Address Allocation
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Contents
Mobile IP Generic NAI Support and Home Address AllocationLast Updated: December 2, 2012
The Mobile IP--Generic NAI Support and Home Address Allocation feature allows a mobile node to be identified by using a network access identifier (NAI) instead of an IP address (home address). The NAI is a character string that can be a unique identifier (username@realm) or a group identifier (realm). Additionally, this feature allows you to configure the home agent to allocate addresses to mobile nodes either statically or dynamically. Home address allocation can be from address pools configured locally on the home agent, through either Dynamic Host Configuration Protocol (DHCP) server access, or from the authentication, authorization, and accounting (AAA) server. Finding Feature InformationYour software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required. Information About Generic NAI Support and Home Address AllocationNAI OverviewAuthentication, Authorization, and Accounting (AAA) servers are used within the Internet to provide authentication and authorization services for dial-up computers. AAA servers identify clients using the NAI. The NAI is a character string in the format of an e-mail address as either user or user@realm but it need not be a valid e-mail address or a fully qualified domain name. The NAI can be used either in a specific or generic form. The specific form, which must contain the user portion and may contain the @realm portion, identifies a single user. The generic form allows all users in a given realm or without a realm to be configured on a single command line. Each user still needs a unique security association, but these associations can be stored on a AAA server. The original purpose of the NAI was to support roaming between dialup ISPs. With the NAI, each ISP need not have all the accounts for all of its roaming partners in a single RADIUS database. RADIUS servers can proxy requests to remote servers for each realm. These services are also valuable for mobile nodes using Mobile IP when the nodes are attempting to connect to foreign domains with AAA servers. The Mobile IP--Generic NAI Support and Home Address Allocation feature introduces a method for the mobile node to identify itself by including the NAI along with the Mobile IP registration request. RFC 2794, Mobile IP Network Access Identifier Extension for IPv4 , defines a mobile node NAI extension of type 131 to the Mobile IP registration messages. This extension must appear in the registration request before the mobile-home authentication extension (MHAE) and mobile-foreign authentication extension (MFAE). The home agent authenticates the mobile node and allocates an IP address. For static IP address allocation, the mobility binding is identified in the home agent as a flow {NAI, IP address} and for dynamic address assignment the mobility binding is identified by the NAI only. Home Address AllocationThe home agent allocates a home address to the mobile node based on the NAI received during Mobile IP registration. The IP addresses can be statically or dynamically allocated to the mobile node. In addition, multiple static IP addresses can be allocated to the same NAI. The home agent will not permit simultaneous registrations for different NAIs with the same IP address, whether it is statically or dynamically allocated.
Static IP AddressesStatic IP addresses must be configured on the mobile node. The home agent supports static IP addresses that might be public IP addresses, or addresses in a private domain.
The mobile user proposes the configured/available address as a nonzero home address in the registration request message. The home agent can accept this address or return another address in the registration reply message. The home agent can authorize the IP address by accessing the AAA server or DHCP server. The AAA server may return the name of a local pool, or a single IP address. On successful Mobile IP registration, Mobile IP based services are made available to the user. Local AuthorizationA static address can be authorized on a per-mobile node or per-realm basis. Per-mobile node configurations require a specific NAI in the form of user or user@realm to be defined on the home agent and allow up to five addresses or a pool per NAI. Per-realm configurations require that a generic NAI be in the form of @realm and only allows address allocation from a local pool. AAA AuthorizationThe number of mobile nodes that can be configured is limited because of NVRAM on the router. So, as an option, you can also store the authorized addresses or local pool name in a AAA server. Each user must have either the static-addr-pool attribute or the static-pool-def attribute configured in the AAA server. Unlike the static address configuration on the command line, the static-addr-pool attribute is not limited in the number of addresses. See the Configuration Examples for Generic NAI Support and Home Address Allocation section in this document for AAA configuration examples. Static IP Address Configuration PriorityIf the configuration exists locally as well as on the AAA server, the AAA configuration takes precedence over the local pool of addresses. The priority is given in the following order:
In cases where the static addresses list is retrieved from the AAA server but all the addresses are already in use by other mobile nodes, the next priority addressing mechanism is used. Dynamic IP AddressesA mobile node can request a dynamically allocated IP address by proposing an all-zero home address in the registration request message. The home agent allocates a home address and returns it to the mobile node in the registration reply message. A fixed address is a dynamically assigned address that is always the same. The home address can be allocated from a AAA server, a DHCP server, or configured locally through the command line interface (CLI). You can also define a local pool for address allocation on a AAA server or through the CLI. DHCPOptionally, Mobile IP uses the existing Cisco IOS DHCP proxy client to allocate dynamic home addresses by a DHCP server. The NAI is sent in the DHCP client-id option and can be used to provide dynamic DNS services. Address Allocation for Same NAI with Multiple Static AddressesThe home agent supports multiple Mobile IP registrations for the same NAI with different static addresses through static address configuration on the command line or by configuring static-ip-address pool (s) at the AAA server or DHCP server. When the home agent receives a registration request message from the mobile user, the home agent accesses the AAA for authentication, and possibly for assignment of an IP address. A single mobile user can use multiple static IP addresses either on the same IP device or multiple IP devices, while maintaining only one AAA record and security association. The ISP can then bill the user based on the NAI, independent of which IP device was used. How Registrations Are Processed for the Same NAIWhen the same NAI is used for registration from two different mobile IP devices, the behavior is as follows:
Additionally, two flows originating from the same mobile node using the same NAI, but two different home agents, are viewed as independent cases. How to Configure Generic NAI Support and Home Address Allocation
Configuring the Home AgentPerform one of the following tasks in this section, depending on whether you want to configure static IP addresses or dynamic IP addresses. DETAILED STEPS Dynamic IP AddressesThis section describes how to configure the home agent to allocate dynamic IP addresses to mobile nodes.
DETAILED STEPS Configuring AAA in the Mobile IP EnvironmentAccess control is the way you manage who has user access to the network server and what services the users are allowed to use. AAA network security services provide the primary framework through which you set up access control on your router or access server. See the Configuration Examples for Generic NAI Support and Home Address Allocation in this document for example AAA configurations. DETAILED STEPS Configuring RADIUS in the Mobile IP EnvironmentRemote Authentication Dial-in User Service (RADIUS) is a method for defining the exchange of AAA information in the network. In the Cisco implementation, RADIUS clients run on Cisco routers and send authentication requests to a RADIUS server that contains all user authentication and network server access information. DETAILED STEPS Verifying Generic NAI Support and Home Address AllocationTo verify generic NAI support and home address allocation, use the following commands in privileged EXEC mode, as needed: DETAILED STEPS
Output ExamplesThis section provides the following output examples:
Sample Output for the show ip mobile binding CommandIn this example, output information about all current mobility bindings is displayed using the show ip mobile bindingEXEC command:
Router> show ip mobile binding nai jane@cisco.com
Mobility Binding List:
jane@cisco.com (Bindings 1):
Home Addr 25.2.2.1
Care-of Addr 68.0.0.31, Src Addr 68.0.0.31,
Lifetime granted 02:46:40 (10000), remaining 02:46:32
Flags Sbdmgvt, Identification B750FAC4.C28F56A8,
Tunnel2 src 1.1.1.1.dest 2.2.2.1 reverse-allowed
Routing Options - (B)Broadcast
Sample Output for the show ip mobile host CommandIn this example, mobile host counters and information is displayed using the show ip mobile hostEXEC command:
Router> show ip mobile host nai jane@cisco.com
jane@cisco.com:
Dynamic address from local pool dynamic-pool
Allowed lifetime 00:03:20 (200/default)
Roaming status -registered-, Home link on virtual network 25.0.0.0/8
Bindings 25.2.2.1
Accepted 2, Last time 04/13/02 19:04:28
Overall service time 00:04:42
Denied 0, Last time -never-
Last code '-never- (0)'
Total violations 0
Tunnel to MN - pkts 0, bytes 0
Reverse tunnel from MN - pkts 0, bytes 0
Sample Output for the show ip mobile visitor CommandIn this example, the visitor list on the foreign agent is displayed using the show ip mobile visitorEXEC command:
Router> show ip mobile visitor nai jane@cisco.com
Security Associations (algorithm,mode,replay)
Mobile Visitor List:
jane@cisco.com
Home addr 25.2.2.2
Interface Ethernet3/2, MAC addr 0060.837b.95ec
IP src 0.0.0.0, dest 2.2.2.1, UDP src port 434
HA addr 1.1.1.1, Identification B7510E60.64436B38
Lifetime 00:03:20 (200) Remaining 00:02:57
Tunnel2 src 2.2.2.1, dest 1.1.1.1, reverse-allowed
Routing Options - (B) Broadcast
Configuration Examples for Generic NAI Support and Home Address Allocation
Static Home Addressing Using NAI ExamplesThe following example configures a local pool of static addresses to be used in assigning IP addresses to mobile nodes in the cisco.com domain: router mobile ! ip local pool mobilenodes 172.21.58.3 172.21.58.250 ip mobile host nai @cisco.com static-address local-pool mobilenodes ip mobile secure host nai @cisco.com spi 100 key hex 123456781234567812345678123245678 ! Dynamic Home Addressing Using NAI ExamplesThe following is an example of dynamic addressing using a local pool: router mobile ! ip local pool my-pool 10.1.2.3 10.1.2.5 ip mobile host nai jane@cisco.com address pool local my-pool virtual-network 10.0.0.0 255.255.255.0 ip mobile secure host nai jane@cisco.com spi 100 key hex 123456781234567812345678123245678 The following is an example of dynamic addressing using a DHCP server specified by the DHCP proxy client: router mobile ! ip mobile host nai jane@cisco.com address pool dhcp-proxy-client dhcp-server 10.1.2.3 interface FastEthernet 0/0 ip mobile secure host nai jane@cisco.com spi 100 key hex 123456781234567812345678123245678 Home Agent Using NAI AAA Server ExampleIn the following static configuration, the home agent can use a AAA server to store either the authorized addresses or local pool name. For the mobile node to request a static address, either the static-addr-pool attribute or the static-pool-def attribute must be configured on the AAA server. Home AgentThe following example shows how the home agent is configured to use the AAA server: aaa new-model aaa authorization ipmobile radius ! ip local pool mobilenodes 10.0.0.5 10.0.0.10 ip mobile host nai user@staticuser.com interface FastEthernet0/0 aaa ip mobile host nai @static.com interface FastEthernet0/0 aaa AAA and Local Configuration ExampleYou can also configure some addressing details on the home agent and some on the AAA server. In the following example, a set of authorized static addresses for a mobile node are configured on the AAA server and the dynamic addresses are configured locally on the home agent. Additional ReferencesFor additional information related to generic NAI support and home address assignment, refer to the following sections: Related Documents
MIBs
1 Not all supported MIBs are listed.
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://tools.cisco.com/ITDIT/MIBS/servlet/index If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL: RFCs
2 Not all supported RFCs are listed.
Technical AssistanceCommand ReferenceThe following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS IP Mobility Command Reference at http://www.cisco.com/en/US/docs/ios/ipmobility/command/reference/imo_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List .
Glossaryhome agent --A router on a home network of the mobile node or that tunnels packets to the mobile node or mobile router while they are away from home. It keeps current location information for registered mobile nodes called a mobility binding. flow --In the context of this document, a flow is the set of {NAI, IP Address}. The flow allows a single NAI to be associated with one or multiple IP addresses, for example, {NAI, ipaddr1}, {NAI, ipaddr2}, and so on. foreign agent --A router on the visited network of a foreign network that provides routing services to the mobile node while registered. The foreign agent detunnels and delivers packets to the mobile node or mobile router that were tunneled by the Home Agent of the mobile node. For packets sent by a mobile node, the Foreign Agent may serve as a default router for registered mobile nodes. mobility binding --The association of a home address with a care-of address and the remaining lifetime. NAI --Network Access Identifier. The user ID submitted by the mobile node during registration to identify the user for authentication. The NAI may help route the registration request to the right home agent.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: 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. (1110R) 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. © 2012 Cisco Systems, Inc. All rights reserved.
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