Routing header based routing in internet protocol (ip)-cellular networks

Description of equivalent WO 2004003690 A2

[0001] ROUTING HEADER BASED ROUTING IN INTERNET

PROTOCOL (IP)-CELLULAR NETWORKS

[0002] BACKGROUND

[0003] This invention relates to cellular networks. More particularly, the invention relates to a technique employing routing headers in internet protocol (IP) packets to route packets to an end destination through intermediate routers employing routing headers.

[0004] Figure 1 shows a typical cellular network such as a Global

System for Mobile Communications/Generalized Packet Switched Service (GSM/GPRS) network. In IP-applications there is a single point of attachment to the external IP-networks such as the Public Internet, the single point of attachment being a gateway general packet radio service support node (GGSN) also referred to in Figure 1 as the gateway router GR. The Gateway Router is connected to the Public Internet and also to X.25 Networks via Firewalls Fl and F2 respectively. On the radio network side, the Gateway Router is coupled to the intra-public land mobile network (Intra-PLMN) internet protocol (IP) backbone for sending two-way data from multiple user equipments (UEs). The IP -layer in the user equipment (UE) terminates at the GGSN which, in turn, means that there is a single "IP-level-hop" from the UE to the GGSN. Figure 2 shows the protocol stacks used for exchanging IP data between the user equipment, also referred to as the mobile station (MS), the base station sub-system (BS), the serving GPRS support node (SGSN) and the gateway GPRS support node (GGSN).

[0005] Typically, the UMTS network is made up of switching elements which transfer the IP -packets through the employment of Layer-2 switching techniques. Some UMTS networks utilize IP -based routing elements. However, the IP-technology is used purely for transport purposes only and is not visible to the UE, meaning that the IP-layer of the UE is still terminated at the GGSN. [0006] It is a clear possibility that future cellular networks will be entirely IP-based. In other words, the cellular network will be an interconnected network of IP-routers with the result that the IP-layer of the UE may be terminated by a nearby router. However, since the network is still assumed to have a single point of attachment to the external IP-networks, IP packets from the nearest router must be routed to the gateway router GR (for example, the GGSN shown in Figure 1). In the prior art, this is achieved by establishing IP-tunnels which involve IP-in-IP encapsulation. This approach has the disadvantages of requiring the need to set up tunnels and the extra overhead due to encapsulation.

[0007] Another scenario is a network of a number of LAN Access

Routers (ARs), wherein each Access Router is connected to a number of Access Points, as shown in Figure 3. A single gateway router serves these ARs and provides connectivity to the external IP-networks. Such a network may also be referred to as an Autonomous System or an IP-domain. Other scenarios include universal mobile telecommunications system (UMTS) networks, code division multiple access CDMA2000 networks etc.

[0008] SUMMARY

[0009] The present invention utilizes internet protocol version 6 (IPv6) throughout the entire cellular network and employs routing headers of the

IPv6 packets to ensure that the packets are routed via the gateway router to the end destination which is accomplished by specifying the IP address of the gateway router as the IP address of an intermediate router in the routing header.

[0010] BRIEF DESCRIPTION OF THE DRAWING(S)

[0011] The present invention will be understood from a consideration of the figures in which like elements are designated by like numerals and, wherein: [0012] Figure 1 shows a typical global system for mobile communications /general packet radio service (GSM/GPRS) cellular network.

[0013] Figure 2 shows the layers making up the mobile station, base station, SGSN and GGSN of Figure 1.

[0014] Figure 3 shows a network employing WLAN Access Routers connected to a number of Access Points.

[0015] Figure 4 shows a network similar to the network of Fig. 3 and further describing the manner in which routers are used as intermediate nodes.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) [0017] The present invention eliminates the disadvantages of the prior art through the utilization of internet protocol version 6 (IPv6) throughout the entire Cellular Network and using Routing Headers of IPv6 packets to ensure that the packets are routed via the gateway router to the end destination. This is accomplished through the present invention by specifying the IP- address of the gateway router as an IP-address of an intermediate router in the routing header.

[0018] As shown in Fig. 3, user IP packets are sent from the UE (see also Figure 1) to the nearest router NR shown, by way of the radio tower T (see Figures 1 and 3) and then to the gateway router GR. The IPv6 header of the User IP packets contain the IP addresses of the gateway router GR in the routing header. At a minimum, the gateway router GR is a simple IP Router that can route IP packets based on their destination IP address. However, the gateway router GR may have additional features, such as Source Address based Routing, Network Address Translation, QoS based Routing (such as DiffServ, MPLS etc), Secure Firewalls, etc. In addition, the gateway router (GR) has the capability of sending messages to the UE as to the addresses of those routers which may be included in a routing header in order to select a router or routers having smaller or no traffic loads. [0019] Another aspect of the invention is the provision of additional routers which serve as nodes. The selection of intermediate routers is based on criteria such as congestion state and/or capacity and/or monitoring needs. For example, noting Fig. 4, the user IP packets are sent from the UE through radio tower T to the nearest router NR, typically referred to as an access router, by way of the radio tower T and then to an intermediate node router such as IN 1 and finally to the gateway router GR, serving as the gateway to the internet. The reason for routing the IP packets via INI may be that INI is not congested with excessive traffic, compared to other routers that could have been used to send IP packets from NR to GR. Alternately, the reason for routing the IP packets via INI may be that traffic monitoring equipment is connected to INI, and a legal requirement that all IP packets emanating from one or more UEs are to be monitored. The IPv6 header of the User IP packets contain the IP addresses of the intermediate router IN 1 and the Gateway Router GR in the Routing Header, eliminating the need for tunneling and encapsulation. There are several ways in which the IPv6 routing headers are populated with the appropriate IP addresses of the gateway router GR as well as additional Intermediate Routers.

[0020] As one example, the UE constructs the IPv6 packets with this routing header information. This method requires that the UE is made aware of the necessary information regarding the IPv6 addresses of the GR and the Intermediate Nodes. For example, the Network may inform the UE prior to data transmission.

[0021] Another technique is to allow the NR to perform this task. In this scenario, the UE need not be aware of the IP routing within the cellular network at all. In fact, the UE may even be an IPv4 device. The Nearest Access Router will be equipped to perform address translation (from IPv4 to IPv6) if necessary and to add the appropriate IPv6 Routing Header. The advantage of this technique is that the NR, being part of the fixed network of the cellular system, can be made aware of the network status (in terms of congestion, failures etc), as well as the need for processing by special intermediate nodes for purposes such as legal interception.

[0022] As another alternative embodiment, the GR may add and/or modify routing headers of received packets and convey the packets to a UE through an access router, access router being a standard term typically designated as the first router communicating with a UE through a radio tower.