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Table Of Contents
Overview of the Cisco Mobile Wireless Home Agent
New Features in IOS Release 12.3(14)YX1
Overview of the Cisco Mobile Wireless Home Agent
This chapter illustrates the functional elements in a typical CDMA2000 packet data system, the Cisco products that are currently available to support this solution. and their implementation in Cisco IOS Mobile Wireless Home Agent software.
This chapter includes the following sections:
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Features
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Feature Overview
Cisco's Mobile Wireless Packet Data Solution includes the Packet Data Serving Node (PDSN) with Foreign Agent (FA) functionality, the Cisco Mobile Wireless Home Agent (HA), Authentication, Authorization and Accounting (AAA) servers, and several other security products and features. The solution is standards compliant, and is designed to meet the needs of the mobile wireless industry as it transitions towards third-generation cellular data services.
The Home Agent is the anchor point for mobile terminals for which MobileIP or Proxy MobileIP services are provided. Traffic sent to the terminal is routed through the Home Agent. With reverse tunneling, traffic from the terminal is also routed through the Home Agent.
A PDSN provides access to the Internet, intranets, and Wireless Application Protocol (WAP) servers for mobile stations using a Code Division Multiple Access 2000 (CDMA2000) Radio Access Network (RAN). The Cisco PDSN is a Cisco IOS software feature that runs on Cisco 7200 routers, Catalyst 6500 switches, and Cisco 7600 Internet routers, and acts as an access gateway for Simple IP and Mobile IP stations. It provides FA support and packet transport for virtual private networking (VPN). It also acts as a AAA client.
The Cisco PDSN and the Cisco Home Agent support all relevant 3GPP2 standards, including those that define the overall structure of a CDMA2000 network, and the interfaces between radio components, the Home Agent, and the PDSN.
System Overview
CDMA is one of the standards for mobile communication. A typical CDMA2000 network includes terminal equipment, mobile termination, base transceiver stations (BTSs), base station controllers (BSCs), PDSNs, and other CDMA network and data network entities. The PDSN is the interface between a BSC and a network router.
Figure 1 illustrates the relationship of the components of a typical CDMA2000 network, including a PDSN and a Home Agent. In this illustration, a roaming mobile station user is receiving data services from a visited access provider network, rather than from the mobile station user's subscribed access provider network.
Figure 1 The CDMA Network
As the illustration shows, the mobile station, which must support either Simple IP or Mobile IP, connects to a radio tower and BTS. The BTS connects to a BSC, which contains a component called the Packet Control Function (PCF). The PCF communicates with the Cisco PDSN through an A10/A11 interface. The A10 interface is for user data and the A11 interface is for control messages. This interface is also known as the RAN-to-PDSN (R-P) interface. For the Cisco Home Agent Release 2.1 and above, you must use a Fast Ethernet (FE) interface as the R-P interface on the Cisco 7200 platform, and a Giga Ethernet (GE) interface on the Cisco Multi-Processor WAN Application Module (MWAM) platform.
The IP networking between the PDSN and external data networks is through the PDSN-to-intranet/Internet (Pi) interface. For the Cisco Home Agent, you can use either an FE or GE interface as the Pi interface.
For "back office" connectivity, such as connections to a AAA server, the interface is media independent. Any of the interfaces supported on the Cisco 7206 can be used to connect to these types of services, but we recommend that you use either an FE or GE interface as the Pi interface.
Cisco Home Agent Network
Figure 2 illustrates the functional elements in a typical CDMA2000 packet data system, and Cisco products that are currently available to support this solution. The Home Agent, in conjunction with the PDSN and Foreign Agent, allows a mobile station with Mobile IP client function, to access the Internet or corporate intranet using Mobile IP-based service access. Mobile IP extends user mobility beyond the coverage area of the current, serving PDSN/Foreign Agent. If another PDSN is allocated to the call (following a handoff), the target PDSN performs a Mobile IP registration with the Home Agent; this ensures that the same home address is allocated to the mobile station. Additionally, clients without a Mobile IP client can also make use of these services by using the Proxy Mobile IP capability provided by the PDSN.
The Home Agent, then, is the anchor point for mobile terminals for which Mobile IP or Proxy Mobile IP services are provided. Traffic is routed through the Home Agent, and the Home Agent also provides Proxy ARP services. In the case of reverse tunneling, traffic from the terminal is also routed through the Home Agent.
Figure 2 Cisco Products for CDMA2000 Packet Data Services Solution
For Mobile IP services, the Home Agent would typically be located within an ISP network, or within a corporate domain. However, many ISPs and/or corporate entities may not be ready to provision Home Agents by the time service providers begin rollout of third-generation packet data services. As a remedy, Access service providers could provision Home Agents within their own domains, and then forward packets to ISPs or corporate domains using VPDN services. Figure 3 illustrates the functional elements that are necessary to support Mobile IP-based service access when the Home Agent is located in the service provider domain.
Figure 3 Cisco Mobile IP-Based Service Access With Home Agent in Service Provider Network
For Mobile IP and Proxy-Mobile IP types of access, these solutions allow a mobile user to roam within and beyond its service provider boundaries, while always being reachable and addressable through the IP address assigned on initial session establishment. Details of Mobile IP and Proxy Mobile IP Services can be found in the Packet Data Services section that follows.
Packet Data Services
In the context of a CDMA2000 network, the Cisco Home Agent supports two types of packet data services: Mobile IP and Proxy Mobile IP services. From the perspective of the Cisco Home Agent, these services are identical.
Cisco Mobile IP Service
With Mobile IP, the mobile station can roam beyond the coverage area of a given PDSN and still maintain the same IP address and application-level connections.
Figure 4 shows the placement of the Cisco Home Agent in a Mobile IP scenario.
Figure 4 CDMA Network—Mobile IP Scenario
The communication process occurs in the following order:
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As part of the registration process, the Cisco HA creates a binding table entry to associate the mobile station's home address with its Care-of Address (CoA).
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Cisco Proxy Mobile IP Service
While PPP, which is widely used to connect to an Internet Service Provider (ISP), is ubiquitous in IP devices, certain service providers lack commercially available Mobile IP client software. As an alternative to Mobile IP, you can use Cisco's Proxy Mobile IP feature. This capability of the Cisco PDSN, which is integrated with PPP, enables the PDSN (functioning as a Foreign Agent) and a Mobile IP client, to provide mobility to authenticated PPP users.
The communication process occurs in the following order:
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Features
New Features in IOS Release 12.3(14)YX1
This section lists features that were introduced or modified in Home Agent Release 12.3(14)YX1:
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This section describes features that were introduced or modified in Home Agent Release 3.0:
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This section lists features that were introduced or modified in previous releases of the Cisco Mobile Wireless Home Agent:
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Feature Support
In addition to supporting Cisco IOS networking features, a Cisco 7200 series router, Cisco 6500 series switch, or Cisco 7600 series router, configured as a Home Agent, supports the following Home Agent-specific features:
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Benefits
The Cisco Mobile Wireless Home Agent provides these additional benefits:
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The Home Agent
The Home Agent (HA) maintains mobile user registrations and tunnels packets destined for the mobile to the PDSN/FA. It supports reverse tunneling, and can securely tunnel packets to the PDSN using IPSec. Broadcast packets are not tunneled. Additionally, the HA performs dynamic home address assignment for the mobile. Home address assignment can be from address pools configured locally, through either DHCP server access, or from the AAA server.
The Cisco HA supports proxy Mobile IP functionality, and is available on the Cisco 7600 series router, Cisco 7200 series router, and Cisco 6500 series switch platforms. A Cisco HA based on the Cisco 7200 series router supports up to 262,000 mobile bindings, can process 100 bindings per second, and is RFC 2002, RFC 2003, RFC 2005 and RFC2006 compliant.
A Cisco HA based on the Cisco 7600 series router or Cisco Catalyst 6500 switch, with two MWAM cards housing five active HA images and five standby images, would support the above figures multiplied by 5.
For more information on Mobile IP as it relates to Home Agent configuration tasks, please refer to the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t1/mobileip.htm.
Posted: Fri Nov 17 00:54:37 PST 2006
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