The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a functional block diagram of a wireless communications system is presented. A home network 102 receives packets from and sends packets to a packet data network (PDN) 104, such as the Internet. A wireless terminal 106 wirelessly connects to the home network 102. For example, the wireless terminal 106 may be a mobile phone, and the home network 102 may be the cellular network of a mobile phone operator.
The wireless terminal 106 is configured to work with the home network 102 and may be unable to connect to the networks of other carriers. In various implementations, the wireless terminal 106 may be able to view content from the PDN 104 via the home network 102. The home network 102 may interconnect with the networks of other service providers.
Referring now to FIG. 2, a functional block diagram of a wireless communications system offering mobility is presented. The home network 102 is connected to one or more visited networks 110-1, 110-2, . . . , and 110-X (referred to herein as visited networks 110). In various implementations, the visited networks 110 may be the networks of other service providers, including service providers in other countries.
In FIG. 2, the mobile wireless terminal 120 has established a wireless connection to the visited network 110-1. The mobile wireless terminal 120 includes the code and data used to communicate with the home network 102 via the visited network 110-1. In this way, the mobile wireless terminal 120 can interface with the home network 102 even when connected to one of the visited networks 110.
The mobile wireless terminal 120 includes mobility features that allow the mobile wireless terminal 120 to communicate with the visited networks 110. The mobile wireless terminal 120 may use a host-based Internet protocol (IP) when handling mobility management. A mobility protocol may include a mobile IP (MIP), which may refer to a host-based IP or a network-based IP. Dual stack mobile IP (DSMIP) is an exemplary host-based mobility protocol. Several versions are available. For example, DSMIPv6 includes a mobile wireless terminal 120 that extends its IP stack when changing its point of attachment. The mobile wireless terminal 120, according to DSMIPv6 is also involved in signalling that enables IP mobility. DSMIPv6 is often referred as client mobile IP (CMIP). DSMIPv6 is described in request for comment (RFC) 3775, titled “Mobility Support in IPv6,” the disclosure of which is hereby incorporated by reference in its entirety.
Referring now to FIGS. 3A-3B, a functional block diagram and timeline of an implementation of host-based mobility are presented, respectively. The mobile wireless terminal 120 roaming in a visited network 110-1 connects through a home agent (HA) 180 of the home network 102 to a packet data network (PDN). The home agent 180 may be included in a gateway (GW) and establishes a logical location of the mobile wireless terminal 120. Packets ultimately destined for the mobile wireless terminal 120 are sent to the home agent 180, while packets from the mobile wireless terminal 120 will appear to originate from the home agent 180.
FIG. 3B shows an example of how the mobile wireless terminal 120 manages its mobility by using DSMIPv6. For example, with DSMIPv6, the mobile wireless terminal 120 is secured using a security protocol, such as Internet key exchange (IKEv2), which is the protocol used to set up a security association (SA) in the Internet Protocol Security (IPsec) suite. IPsec includes a suite of protocols for securing IP communications by authenticating and/or encrypting each IP packet in a data stream.
The mobile wireless terminal 120 may register a current location of the mobile wireless terminal 120 with the home network 102 and thus receive session continuity during roaming by using DSMIPv6. To register the current location, the mobile wireless terminal 120 may require a home address, a home agent address and a security association with the home agent 180. The procedure to obtain such information is referred to as “bootstrapping”, and the mobile wireless terminal 120 may use various information protocols, such as Directory Name Service (DNS) or Dynamic Host Configuration Protocol (DHCP), to obtain such information dynamically during bootstrapping.
When the mobile wireless terminal 120 attaches to a visited network 110-1, the mobile wireless terminal 120 first performs layer 2 and layer 3 attach procedures. Layer 2 and layer 3 attach procedures are procedures of the Open Systems Interconnection Basic Reference Model (OSI Model). During the layer 2 and layer 3 attach procedures, the mobile wireless terminal 120 acquires a topology-correct IP address, commonly referred to as a care-of address (CoA). For the layer 2 attach procedure, the mobile wireless terminal 120 may establish a connection to an access router (AR) 182 within the visited network 110-1. In various implementations, additional access routers (not shown) may be present. The access router 182 may communicate with other networks, including the home network 102 and/or a corporate network (CN).
When the mobile wireless terminal 120 connects to the visited network 110-1, the mobile wireless terminal 120 performs authentication and authorization with the access router 182. This may include communicating with an authentication, authorization, and accounting (AAA) server in the home network 102. The AAA server may retrieve information based on an identifier of the mobile wireless terminal 120, such as a network address identifier, that uniquely identifies the mobile wireless terminal 120. The AAA server may indicate to the access router 182 whether the mobile wireless terminal 120 should be allowed access to the home network 102 and what services should be provided to the mobile wireless terminal 120.
Upon authentication, the mobile wireless terminal 120 receives a local address from the access router 182. Using this local address, the mobile wireless terminal 120 may implement layer 3 attach procedures to communicate with various network elements, including the home agent 180. The mobile wireless terminal 120 may then initiate a bootstrapping procedure by providing an access point name (APN) during either DHCP or DNS to obtain, for example, a home agent address. An access point name may include a logical name that identifies a Packet Data Network (PDN). The mobile wireless terminal 120 may include a list of access point names or other identifiers for various PDNs.
The mobile wireless terminal 120 may then establish a security association with the home agent 180 through, for example, IPSec IKEv2, in order to obtain a home address (HoA) from the home network 102. The mobile wireless terminal 120 may send the information of the CoA and HoA in a binding update message to the home agent 180. Upon receiving the binding update message, the home agent 180 may “bind” the CoA and the HoA in a binding cache. In one implementation, the home agent 180 creates a binding cache entry that records information about the mobile wireless terminal 120, including the current address of the mobile wireless terminal 120.
The home agent 180 may send a binding acknowledgement (Ack) message to notify the mobile wireless terminal 120 of the status of the binding update. The binding acknowledgement message may also include the HoA so that the mobile wireless terminal 120 is aware of a global home address assigned to the mobile wireless terminal 120. The mobile wireless terminal 120 may therefore “connect” to the home agent 180 via the exchange of the binding update and binding acknowledgement messages. The home agent 180 may use the binding cache entry to forward packets from destinations associated with the home network 102 to a current point of attachment of the mobile wireless terminal 120.
For example, packets sent from other network elements, such as other mobile wireless terminals, are sent to that HoA. The home agent 180 receives those packets and forwards the packets to the mobile wireless terminal 120. Similarly, packets from the mobile wireless terminal 120 are first forwarded to the home agent 180. The home agent 180 then forwards the packets with the source address of HoA. To allow for packets to be exchanged between the mobile wireless terminal 120 and the home agent 180, a tunnel may be established between the mobile wireless terminal 120 and the home agent 180.
Referring now to FIGS. 4A-4B, the mobile wireless terminal 120 may set up the connectivity to multiple PDNs 104-1, 104-2 (collectively referred to as PDNs 104) via multiple home agents in respective PDN GWs 316-1, 316-2 (collectively referred to as PDN GWs 316) using DSMIP. The timeline of FIG. 4B includes the mobile wireless terminal 120 attaching to each of the PDN GWs 316 via a procedure similar to the one shown in FIG. 3B. In other words, the mobile wireless terminal 120 uses separate DSMIP bootstrapping procedures to connect to each of the PDN GWs 316.
Each PDN GW 316 may include one or more home agents that each have respective addresses. However, for simplicity, the terms PDN GW and home agent may be used interchangeably herein. The mobile wireless terminal 120 may establish tunnels to either or both the home agents to route traffic to the appropriate home agent based on the service associated with that traffic. For example, one PDN 104-1 may be used to provide a service such as push e-mail, while another PDN 104-2 may be used to provide voice over internet protocol (VoIP) telephony.