Method and apparatus for route optimisation in nested mobile networks

Abstract

A method of transmitting at least one data packet from a communication node in a data communication network. The method includes receiving (920) a request at a communication node, to transmit at least one data packet to a first destination address and searching (930) for the (first) destination address in a cache of the communication node. A determination (960) of an intermediary address of the destination address is made. The destination address is then replaced with the intermediary address and the steps of searching, determining and replacing are repeated, until no new intermediary address is found. The at least one data packet is then transmit (970) to the destination address via the identified intermediary address(es). A communication unit (corresponding node) communication message and method for building a linked binding cache are also described. In this manner, an optimised data path is determined in order to send at least one data packet to an intended recipient, for example in a nested mobile network scenario.

Description

FIELD OF THE INVENTION [0001] This invention relates to telecommunication systems in which data flows between mobile nodes, for example personal digital assistants with wireless communication capability, and a data network, for example the Internet. BACKGROUND OF THE INVENTION [0002] The Internet is becoming more and more popular, and users increasingly wish to access the Internet whilst on the move. Different types of mobile nodes (i.e. mobile communication units) may be employed for this purpose, for example a mobile telephone or a personal digital assistant (PDA) with wireless communication capability. [0003] Increasingly, mobile users are accessing the Internet via different types of fixed or wireless access networks, for example a cellular radio communication network, such as a Universal Mobile Telecommunication System (UMTS) network, a HiperLAN / 2 or IEEE 802.11b local area network, a Bluetooth local communication system, or fixed accesses such as the Ethernet, and so on. The d...

AI Technical Summary

Benefits of technology

[0151] The invention, or at least embodiments thereof, tend to provide the following advantages, singly or in combination:

[0152] (i) A data packet may be transmitted much more efficiently, with a minimum of number of tunnelling operations performed by intermediary home agents, thereby achieving improved route optimisation.

Problems solved by technology

The lack of knowledge of a true location of a particular MNN results from the HA not knowing any (never mind a preferred) data route to the Mobile Network, once it has moved to a ‘visited’ location.

Unfortunately, when a MR registers with its HA the MR only informs the HA to record a host-specific route in its routing table.

However, it has also been determined that IPv4 does not support route optimisation for MNNs behind the MR.

This problem is exacerbated in the case of nested mobility, which is where a CN wishes to pass data to a MNN that is behind a number of MR links, or a mobile node visiting a mobile network.

This is clearly inefficient routing.

Clearly, the solution proposed does not provide any support for route optimisation, since both inbound and outbound packets are routed through the Home Agent of both MRs 150, 260.

Once again, this is clearly inefficient routing, particularly for a practical situation whereby there may be many more than two levels in the nested network.

However, the scope of this draft has explicitly excluded the case of nested mobility, which presents a significant hurdle to efficient route optimisation.

As such, the solution proposed in the Thierry Ernst document, IETF Internet-Draft draft-ernst-mobileip-v6-network-02.txt, June 2001, fails to provide a useful solution to route optimisation in many practical situations.

Notably, the problems emanating from using this mechanism in a nested mobility are highlighted.

However, if there were n successive levels of nested mobility, this solution provides minimal route optimisation, no more than having a CN2255→HAn−1→HAn−2→ .

This proposal is therefore still clearly inefficient, particularly in the case of nested networks.

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