Communication apparatus and method for inter-as routing

• US 20050089015A1
• Filed: 08/26/2004
• Published: 04/28/2005
• Est. Priority Date: 10/24/2003
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Communication Technologies, Ltd. (Hitachi, Ltd.)
• Inventors: Tsuzuki, Akihito, Tsuge, Munetoshi
• Granted Patent: US 7,529,254 B2
• Time in Patent Office: Days
• US Class Current: 370/351
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing

Abstract

Disclosed here is a communication apparatus and method for inter-AS routing, which enables policy routing between a stub AS and an upstream AS. The policy routing includes control which is applicable only between adjacent autonomous systems (AS'"'"'s). When a subject communication apparatus notifies its own AS number or advertises attribute information that includes its own AS number to a stub AS, the communication apparatus does not use its own AS number or uses the AS number of the upstream autonomous system (AS) instead of its own AS number. In addition, when relaying routing information received from one AS to another, the subject communication apparatus also relays attribute information without discarding the information, although the information is conventionally not relayed to itself.

Claims

1. A communication apparatus for connecting a stub network group consisting of one or more stub networks assigned a predetermined AS (Autonomous System) number respectively to an upstream network assigned an AS number, said communication apparatus having its own AS number, comprising:

means for storing said own AS number;

an interface for sending/receiving a routing message for controlling forwarding of information between autonomous systems (AS) in accordance with a predetermined protocol and an own AS number notification message to notify its own AS number to a communication apparatus deployed in said stub network or said upstream network;

notifying means for notifying said routing message and said own AS number notification message to said communication apparatus through said interface;

a processor for processing said routing message; and

storage means for storing a routing software program used for said routing,

wherein said processor, when sending said own AS number notification message to said communication apparatus deployed in a stub network, notifies said upstream network AS number to said communication apparatus instead of its own AS number;

wherein said processor, when relaying a routing message received from said upstream network to a stub network, processes said routing message without discarding information ruled by said routing protocol so as to pass an AS and not to be relayed thereto, said not-to-be-relayed-information being included in the information related to a preferential route of packet forwarding.

3. The communication apparatus according to claim 1,

wherein said communication apparatus includes storage means for storing a set of AS numbers that are not included in any routing message to be sent to any stub network;

and

wherein said processor, when relaying a routing message received from said upstream network to a stub network, does not discard said routing message even when its own AS number is included in the AS record information of AS'"'"'s passed by said routing message, deletes all the AS numbers in said set of AS numbers from said AS record information, and processes said routing message without adding said own AS number to said AS record information, said AS record information being included in said routing message.

4. The communication apparatus according to claim 3,

wherein said communication apparatus processes said routing message using its own AS number instead of said set of AS numbers.

5. The communication apparatus according to claim 3,

wherein said processor, when processing said routing message received from a stub network, does not discard said routing message even when its own AS number is included in said AS record information of AS'"'"'s passed by said routing message to process said routing message, said AS record information being included in said routing message.

6. The communication apparatus according to claim 5,

wherein said processor, when processing a routing message received from a stub network, discards said routing message if the AS number of said upstream network is included in said AS record information of AS'"'"'s passed by said routing message, said AS record information being included in said routing message.

7. The communication apparatus according to claim 3,

wherein said processor, when processing a routing message received from a stub network, deletes all the AS numbers included in said set of AS numbers from said AS record information of AS'"'"'s passed by said routing message to process said routing message, said AS record information being included in said routing message.

8. The communication apparatus according to claim 3,

wherein a BGP is used as said routing protocol.

9. The communication apparatus according to claim 8,

wherein an MED (Multi Exit Discriminator) attribute is used as information related to a packet forwarding preferential route, said information being ruled by said routing protocol so as to pass said AS and not to be relayed thereto.

10. The communication apparatus according to claim 3,

wherein a BGP is used as said routing protocol and an AS path attribute is used as the record information of said AS'"'"'s passed by said routing message.

11. A communication apparatus according to claim 1, wherein the communication apparatus executes one or more functions of virtual communication apparatuses only in itself.

2. A communication apparatus for connecting a stub network group consisting of one or more stub networks assigned a predetermined AS (Autonomous System) number respectively to an upstream network assigned an AS number, said communication apparatus having its own AS number, comprising:

means for storing said own AS number;

an interface for sending/receiving a routing message for controlling forwarding of information between autonomous systems (AS) in accordance with a predetermined protocol and an own AS number notification message to notify its own AS number to a communication apparatus deployed in said stub network group or said upstream network;

notifying means for notifying said routing message and said own AS number notification message to said communication apparatus through said interface;

a processor for processing said routing message; and

storage means for storing a routing software program used for said routing,

wherein said processor, when sending said own AS number notification message to said communication apparatus deployed in a stub network, notifies said upstream network AS number to said communication apparatus instead of its own AS number; and

wherein said processor, when relaying a routing message received from a stub network to said upstream network, processes said routing message without discarding information ruled by said routing protocol so as to pass an AS and not to be relayed thereto, said not-to-be-relayed-information being included in information related to a preferential route of packet forwarding.

18. The communication apparatus according to claim 2,

wherein said communication apparatus includes storage means for storing a set of AS numbers that are not included in any routing message to be sent to any stub network;

and

wherein said processor, when relaying a routing message received from said upstream network to a stub network, does not discard said routing message even when its own AS number is included in the AS record information of AS'"'"'s passed by said routing message, deletes all the AS numbers in said set of AS numbers from said AS record information, and processes said routing message without adding said own AS number to said AS record information, said AS record information being included in said routing message.

19. The communication apparatus according to claim 18,

wherein said communication apparatus processes said routing message using its own AS number instead of said set of AS numbers.

20. The communication apparatus according to claim 18,

wherein said processor, when processing said routing message received from a stub network, does not discard said routing message even when its own AS number is included in said AS record information of AS'"'"'s passed by said routing message to process said routing message, said AS record information being included in said routing message.

21. The communication apparatus according to claim 20,

wherein said processor, when processing a routing message received from a stub network, discards said routing message if the AS number of said upstream network is included in said AS record information of AS'"'"'s passed by said routing message, said AS record information being included in said routing message.

22. The communication apparatus according to claim 18,

wherein said processor, when processing a routing message received from a stub network, deletes all the AS numbers included in said set of AS numbers from said AS record information of AS'"'"'s passed by said routing message to process said routing message, said AS record information being included in said routing message.

23. The communication apparatus according to claim 18,

wherein a BGP is used as said routing protocol.

24. The communication apparatus according to claim 23,

wherein an MED (Multi Exit Discriminator) attribute is used as information related to a packet forwarding preferential route, said information being ruled by said routing protocol so as to pass said AS and not to be relayed thereto.

25. The communication apparatus according to claim 18,

wherein a BGP is used as said routing protocol and an AS path attribute is used as the record information of said AS'"'"'s passed by said routing message.

26. A communication apparatus according to claim 2, wherein the communication apparatus executes one or more functions of virtual communication apparatuses only in itself.

12. A communication method about inter-AS routing protocol, said method employed for a network for connecting a stub network group consisting of one or more stub networks, each having a predetermined AS number assigned to itself, to an upstream network assigned an AS number differently from any of said AS numbers assigned to said stub networks through a first router, said method comprising the steps of:

enabling said first router to send a message to notify the AS number of said upstream network to a second router deployed in said stub network as its own AS number;

enabling said first router to send a message for notifying a predetermined AS number different from said upstream network AS number and the AS number of any of said stub networks in said stub network group to a third router deployed in said upstream network as its own AS number; and

enabling said first router to receive a routing message from said third router and send said message together with unmodified information ruled by said routing protocol so as to pass an AS and not to be relayed thereto to said second router, said not-to-be-relayed information being included in the information related to a packet forwarding preferential route set in said routing message received by said first router.

14. The communication method according to claim 12,

wherein said first router, when relaying a routing message received from said third router to said second router, relays said routing message even when its own AS number notified to said third router is included in the AS record information of AS'"'"'s passed by said routing message and does not include its own AS number in the AS record information stored in said relayed message, said AS record information being included in said routing message.

15. The communication method according to claim 12,

wherein a BGP is used as said inter-AS routing protocol.

16. The communication method according to claim 15,

wherein information related to a packet forwarding preferential route is an MED attribute, said information related to said packet forwarding preferential route being ruled by said routing protocol so as to pass said AS and not to be relayed thereto.

17. The communication method according to claim 14,

wherein a BGP is used as said inter-AS routing protocol and AS record information of AS'"'"'s passed by said routing message is an AS path attribute.

13. A communication method about inter-AS routing protocol, said method employed for a network for connecting a stub network group consisting of one or more stub networks, each having a predetermined AS number assigned to itself, to an upstream network assigned an AS number differently from any of said AS numbers assigned to said stub networks through a first router respectively, said method comprising the steps of:

enabling said first router to send a message to notify the AS number of said upstream network to a second router deployed in said stub network as its own AS number;

enabling said first router to send a message to notify a predetermined AS number different from any of said upstream network AS number and the AS numbers of said stub networks in said stub network group to a third router deployed in said upstream network as its own AS number; and

enabling said first router to receive a routing message from said second router and send said message together with unmodified information ruled by said routing protocol so as to pass an AS and not to be relayed thereto to said third router, said not-to-be-relayed information being included in information related to a packet forwarding preferential route included in said routing message received by said first router.

27. The communication method according to claim 13,

wherein said first router, when relaying a routing message received from said third router to said second router, relays said routing message even when its own AS number notified to said third router is included in the AS record information of AS'"'"'s passed by said routing message and does not include its own AS number in the AS record information stored in said relayed message, said AS record information being included in said routing message.

28. The communication method according to claim 13,

wherein a BGP is used as said inter-AS routing protocol.

29. The communication method according to claim 28,

wherein information related to a packet forwarding preferential route is an MED attribute, said information related to said packet forwarding preferential route being ruled by said routing protocol so as to pass said AS and not to be relayed thereto.

30. The communication method according to claim 27,

wherein a BGP is used as said inter-AS routing protocol and AS record information of AS'"'"'s passed by said routing message is an AS path attribute.