Method of Operating a System

• US 20080031257A1
• Filed: 07/15/2005
• Published: 02/07/2008
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: He, Liwen
• Granted Patent: US 8,014,399 B2
• Time in Patent Office: Days
• US Class Current: 370/395.31
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/033 by updating distance vector protocols
• CPC Class Codes: H04L 45/06 Deflection routing, e.g. hot-potato routing
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/26 Route discovery packet
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 63/1466 Active attacks involving interception, injection, modification, spoofing of data unit addresses, e.g. hijacking, packet injection or TCP sequence number attacks

Abstract

A method of operating a data network, of the type in which a number of inter-connected router devices forward received packets of data towards a destination node in accordance with a routing table associated with each router. The method comprises: receiving routing information at one of said routers, determining if the information is such that, if it were correct, it would cause the router to update its routing table in respect of one or more entries, and, if so, sending out two test packets, one of which is sent out according to the existing information contained in the routing table and the other of which is sent out according to the information which would be included in the routing table if it were up-dated in accordance with the received information; comparing the results of the two test sending; and updating the routing table to reflect the received information if the comparison indicates that the received information is correct, but otherwise ignoring the information and maintaining the routing table unchanged.

Claims

1. A method of operating a data network, of the type in which a number of interconnected router devices forward received packets of data towards a destination node in accordance with a routing table associated with each router, the method comprising:

receiving routing information at one of said routers, determining if the information is such that, if it were correct, it would cause the router to update its routing table in respect of one or more entries, and, if so, sending out two test packets, one of which is sent out according to the existing information contained in the routing table and the other of which is sent out according to the information which would be included in the routing table if it were up-dated in accordance with the received information;

comparing the results of the two test sendings; and

updating the routing table to reflect the received information if the comparison indicates that the received information is correct, but otherwise ignoring, the information and maintaining the routing table unchanged.

2. A method as claimed in claim 1 wherein the packets of data are transmitted over the network using the Internet Protocol.

3. A method as claimed in claim 1 wherein the test packets are generated with random sequence ID numbers.

4. A method as claimed in claim 1 wherein the test packets are sent with a random amount of data padding.

16. A computer program or suite of programs operable to cause the method of claim 1 to be performed during execution of the program or programs.

17. A carrier medium or media carrying the computer program or programs of claim 16.

5. Use of a router within a data network or internetwork in which data packets may be sent from a source node within the network or internetwork to a destination node via multiple hops between adjacent routers to transmit received data packets towards a destination node, wherein the router maintains a routing table and determines how to forward received data packets requiring onward transmission by consulting the routing table, comprising receiving network configuration information, determining if the information indicates that the router should modify its routing table in respect of one or more entries, and, if so, performing a test to establish whether or not the routing table should in fact be modified in the manner indicated by the received information, and if so to update the routing table accordingly, but otherwise to leave the routing table unamended.

6. Use of a router as claimed in claim 5 wherein the test comprises transmitting two diagnostic packets to a destination node whose route is prospectively to be altered in the routing table in the event of positive test results, via the current route and the prospective new route respectively and determining which route gives rise to the shortest delay.

7. Use of a router as claimed in claim 5 wherein packets of data to be forwarded are transported over the network using the Internet Protocol.

8. Use of a router as claimed in claim 6 wherein the test packets are generated with random sequence ID numbers.

9. Use of a router as claimed in claim 6 wherein the test packets are sent with a random amount of data padding.

10. A router for use in a data network, the router comprising:

storage means for storing a routing table;

a plurality of communication ports for transmitting data to and receiving data from interconnected nodes when the router is in use as part of an interconnected network or internetwork of nodes or networks; and

a processor or group of processors for processing information received at one or more of the communication ports concerning network configuration, and for updating the routing table in accordance with the received network configuration information, characterised in that the processor or group of processors is additionally operable, upon receipt of new network configuration information, to determine if the information indicates that the router should modify its routing table in respect of one or more entries, and, if so, to perform a test to establish whether or not the routing table should in fact be modified in the manner indicated by the received information, and if so to update the routing table accordingly, but otherwise to leave the routing table unamended.

11. A router according to claim 10 wherein the test comprises sending out a pair of test packets in respect of the or each entry which the router determines ought to be changed in view of the received network configuration information, wherein one of the test packets of the or each such pair is sent out according to the existing information contained in the routing table and the other of which is sent out according to the information which would be included in the routing table if it were up-dated in accordance with the received information.

12. A router according to claim 10 operating in accordance with the Internet Protocol.

13. A router according to claim 11 wherein the test packets are generated with random sequence ID numbers.

14. A router according to claim 11 wherein the test packets are sent with a random amount of data padding.

15. A data network or internetwork comprising a plurality of routers according to claim 10.