Method and Apparatus for Route Optimization in a Telecommunication Network

Abstract

A method, access node, and mobile node for controlling the routing of a data packet sent from the mobile node towards a correspondent node of a foreign Internet Protocol (IP)-based telecommunication network different from a home network associated with the mobile node. The access router intercepts the data packet and determines whether the packet relates to a route optimization mode of the Mobile IP standard in which data packets bypass a home agent associated with the mobile node's home network, or whether the packet relates to a bidirectional tunneling mode of the Mobile IP standard in which home agent packets pass through the home agent. The access router drops the packet when the packet relates to the route optimization mode and when dropping of the packet is determined to be in accordance with the predetermined routing policy.

1 . A method of controlling the routing of data packets sent from a first node towards a second node of a telecommunication network, the first node being a mobile node having an associated home network, and the method comprising:
 intercepting such a data packet;   determining if the packet relates to a first mode of communication between the first and second nodes in which data packets generally bypass a home agent associated with the first node's home network, through which home agent packets would generally pass in a second mode of communication between the first and second nodes different to the first mode; and   dropping the packet if it is so determined and if dropping of the packet is determined to be in accordance with a predetermined routing policy.   
     
     
         2 . A method as claimed in any preceding claim, comprising determining whether the dropping of the packet is in accordance with the routing policy in dependence on the packet's destination address. 
     
     
         3 . A method as claimed in  claim 2 , wherein the destination address is one of a home address and a care-of address. 
     
     
         4 . A method as claimed in any preceding claim, comprising determining whether the dropping of the packet is in accordance with the routing policy in dependence on the packet's source address. 
     
     
         5 . A method as claimed in  claim 4 , when dependent on  claim 2 , comprising determining that the packet should be dropped if the packet's source address is a local address, unless the delivery of such a packet is allowed by the routing policy according to the packet's destination address. 
     
     
         6 . A method as claimed in any preceding claim, comprising determining whether the dropping of the packet is in accordance with the routing policy in dependence on a routing header in the packet. 
     
     
         7 . A method as claimed in any preceding claim, comprising determining that the packet relates to the first mode of communication if it relates to a control message associated with the first mode. 
     
     
         8 . A method as claimed in any preceding claim, wherein the first mode of communication is a route optimization mode of the Mobile IP standard and the second mode is a bidirectional tunnelling mode of the Mobile IP standard. 
     
     
         9 . A method as claimed in  claim 8 , when dependent on  claim 7 , wherein control messages associated with the first mode comprise at least one type of IPv6 mobility message. 
     
     
         10 . A method as claimed in  claim 8  or  9 , when dependent on  claim 7 , wherein control messages associated with the first mode comprise at least one of the following types of message: a Binding Update message; a Home Test Init Message; and a Care-of Test Init message. 
     
     
         11 . A method as claimed in any preceding claim, comprising determining whether the packet relates to the first mode of communication in dependence on at least one of the packet's source and destination address. 
     
     
         12 . A method as claimed in any preceding claim, wherein the second node is a stationary node. 
     
     
         13 . A method as claimed in any preceding claim, further comprising sending an error message to the first node if the packet is dropped. 
     
     
         14 . A method as claimed in  claim 13 , wherein the error message is an ICMP Administratively prohibited message. 
     
     
         15 . A method as claimed in any preceding claim, wherein the routing policy specifies at least one IP address range, the routing policy specifying for the or each range whether a packet having a source address that falls within that range is to be dropped or allowed. 
     
     
         16 . A method as claimed in any preceding claim, wherein the routing policy specifies at least one IP address range, the routing policy specifying for the or each range whether a packet having a destination address that falls within that range is to be dropped or allowed. 
     
     
         17 . A method as claimed in any preceding claim, wherein the telecommunication network is an IP based telecommunication network. 
     
     
         18 . A method as claimed in  claim 17 , wherein the IP network is based on at least one of the IP protocols IPv4 and IPv6. 
     
     
         19 . A method as claimed in any preceding claim, comprising intercepting the packet in a visited network if the first node has roamed outside of its home network into the visited network, else intercepting the packet in the home network. 
     
     
         20 . A method as claimed in any preceding claim, wherein the routing policy is stored in the network entity that intercepts the packet. 
     
     
         21 . A method as claimed in any preceding claim, comprising performing the steps in an Access Router. 
     
     
         22 . A method as claimed in any preceding claim, comprising managing the routing policy from a remote location. 
     
     
         23 . A method as claimed in  claim 22 , comprising managing the routing policy remotely via management signalling. 
     
     
         24 . A method as claimed in  claim 23 , wherein the management signalling uses any of the Diameter or COPS protocols. 
     
     
         25 . An apparatus for controlling the routing of data packets sent from a first node towards a second node of a telecommunication network, the first node being a mobile node having an associated home network, and the apparatus comprising:
 means for intercepting such a data packet;   means for determining if the packet relates to a first mode of communication between the first and second nodes in which data packets generally bypass a home agent associated with the first node's home network, through which home agent packets would generally pass in a second mode of communication between the first and second nodes different to the first mode; and   means for dropping the packet if it is so determined and if dropping of the packet is determined to be in accordance with a predetermined routing policy.   
     
     
         26 . A method of controlling the sending of data packets from a first node towards a second node of a telecommunication network, the first node being a mobile node having an associated home network, and the method comprising: not sending such a packet if it would relate to a first mode of communication between the first and second nodes in which data packets generally bypass a home agent associated with the first node's home network, through which home agent packets would generally pass in a second mode of communication between the first and second nodes different to the first mode, unless the sending of such a packet is determined to be in accordance with a predetermined routing policy. 
     
     
         27 . A method as claimed in  claim 26 , comprising determining whether the sending of such a packet is in accordance with the routing policy in dependence on the packet's destination address. 
     
     
         28 . A method as claimed in  claim 26  or  27 , comprising determining whether the sending of such a packet is in accordance with the routing policy in dependence on the packet's source address. 
     
     
         29 . A method as claimed in  claim 26 ,  27  or  28 , comprising determining that such a packet would relate to the first mode of communication if it is a control message associated with the first mode. 
     
     
         30 . A method as claimed in any one of  claims 26  to  29 , comprising managing the routing policy in dependence on error messages received in response to the previous sending of such packets, the error messages indicating that the packets have been dropped. 
     
     
         31 . A method as claimed in any one of  claims 26  to  30 , wherein the routing policy specifies at least one IP address range, the routing policy specifying for the or each range whether a packet having a destination address that falls within that range is allowed to be sent. 
     
     
         32 . An apparatus for controlling the sending of data packets from a first node towards a second node of a telecommunication network, the first node being a mobile node having an associated home network, and the apparatus comprising: means for preventing the sending of such a packet if it would relate to a first mode of communication between the first and second nodes in which data packets generally bypass a home agent associated with the first node's home network, through which home agent packets would generally pass in a second mode of communication between the first and second nodes different to the first mode, unless the sending of such a packet is determined to be in accordance with a predetermined routing policy. 
     
     
         33 . An operating program which, when run on an apparatus, causes the apparatus to carry out a method as claimed in one of  claims 1  to  24  and  26  to  31 . 
     
     
         34 . An operating program which, when loaded into an apparatus, causes the apparatus to become an apparatus as claimed in  claim 25  or  32 . 
     
     
         35 . An operating program as claimed in  claim 33  or  34 , carried on a carrier medium. 
     
     
         36 . An operating program as claimed in  claim 35 , wherein the carrier medium is a transmission medium. 
     
     
         37 . An operating program as claimed in  claim 35 , wherein the carrier medium is a storage medium.