SYSTEM FOR SWITCHING BETWEEN COMMUNICATION DEVICES, SWITCHING METHOD, AND SWITCHING PROGRAM

• US 20090103537A1
• Filed: 05/11/2006
• Published: 04/23/2009
• Est. Priority Date: 05/24/2005
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Takahashi, Masahiko
• Granted Patent: US 8,396,062 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 2101/663 Transport layer addresses, e.g. aspects of transmission control protocol [TCP] or user datagram protocol [UDP] ports
• CPC Class Codes: H04L 49/256 Routing or path finding in ATM switching fabrics
• CPC Class Codes: H04L 49/60 Software-defined switches
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/2546 Arrangements for avoiding unnecessary translation
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1086 session scope modification
• CPC Class Codes: H04L 65/1094 Inter-user-equipment sessions transfer or sharing
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1014 based on the content of a request
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066

Abstract

A switching system in which a unique additional address is used for each session, and session information is transferred as it is without rewriting the session information when a communication device such as a server is switched, a switching method, and a switching program are disclosed. The switching system comprises a switching device (210) for selecting an address for each session from a first communication device, attaching the address to a packet from the first communication device in place of a destination address of the packet, and sending the packet, a dispatcher (240) for setting up a session with the first communication device, selecting a server to deal with the request from the first communication device, and transferring the set up session to a second communication device, and servers (250-1, . . . , 250-n) for taking over the session transferred by the dispatcher and dealing with the request from the first communication device.

Claims

1. A switching system comprising:

an address converting section to select an unused address and to rewrite a destination address of a packet transmitted from a first communication device into the selected address and to send out the rewritten address;

a session setup section to receive a packet using said selected address as its destination and to set up a session with said first communication device; and

a session transferring section to transfer the setup session to a second communication device.

2. A switching system comprising:

an address converting section to select an unused address and to rewrite a destination address of a packet transmitted from a first communication device into the selected address and to send out the rewritten address;

a session setup section to receive the packet having assigned unused address containing said selected address using said address as its destination and to set up a session with said first communication device; and

a session transferring section to transfer the set-up session together with said selected address to a second communication device;

wherein said session setup section deletes, after said set-up session is transferred, said selected address from assigned addresses.

3. A switching system being provided with a system address representing a plurality of first communication devices for connecting a second communication device making a request for session using said system address as its destination of a packet to any one of said plurality of first communication devices, comprising:

an address converting section to select an additional address being able to be arbitrarily used and to rewrite a destination address of a packet received from said second communication device into the selected additional address and to send out said packet having a rewritten address;

a session setup section to receive said packet having assigned said additional address using said selected additional address as its destination and to set up a session with said second communication device; and

a session transferring section to transfer information about said set-up session containing said selected additional address to one selected from said plurality of first communication devices;

wherein said selected additional address, after said information about said set-up session is transferred, is deleted from addresses of said packet assigned in said session setup section.

4. A switching system provided with a system address representing a plurality of server devices each having a fixed address for connecting a client device making a request for session using said system address as its destination of a packet to any one of said plurality of server devices, comprising:

an address converting section to select an unused additional address being different from said fixed address and being able to be arbitrarily used and to rewrite a destination address received from said client device into the selected additional address;

a session setup section to receive a packet having said unused additional address and using said selected additional address as its destination and to set up a session with said client device; and

a session transferring section to transfer information about the set-up session containing said selected additional address to a selected server device;

wherein said session setup section deletes, after said information about said set-up session is transferred, said selected additional address to make the state usable.

5. A switching system being provided with a system address being set to a local network containing a plurality of server devices each having a fixed address and representing said plurality of server devices for connecting a client device outside said local network making a request for session using said system address as its destination of a packet to any one of said plurality of server devices, comprising:

an address converting section to manage an additional address being able to be arbitrarily used in addition to said fixed address and to select an unused additional address and to rewrite a destination address of a packet received from said client device into the selected additional address;

a session setup section to receive said packet having assigned said unused additional address using said selected additional address as its destination and to set up a session with said client device; and

a session transferring section to transfer information about the set-up session containing said selected additional address to one server device selected from said plurality of server devices;

wherein said selected additional address is deleted, after said information about said set-up session is transferred to the selected server device, from said additional address assigned to said session setup section and the state is made to be usable.

6. A switching system comprising an address converting section to select an unused address, when a packet destined to a specified address is received from a first communication device, and to rewrite a destination address of said packet destined to said specified address received from said first communication device into the selected address and to send out the packet having the rewritten address to a network.

7. The switching system according to claim 6, wherein, in a network system having a system address representing a plurality of communication devices, said address converting section rewrites a destination of a packet using said system address transmitted from said first communication device as its destination into said selected address and a source address into said system address.

8. The switching system according to claim 7, wherein, in a network system having a system address representing a plurality of communication devices, said address converting section rewrites a destination of a packet using said system address from said first communication device as its destination into said selected address and a source address of a packet using said selected address as its destination into said system address.

9. A dispatcher comprising a session setup section to set up, when a packet destined for an address temporarily assigned is received as a request for new session, a session with a first communication device serving as a source device of packet and a session transferring section to transfer the setup session to a second communication device.

10. The dispatcher according to claim 9, further comprising an analyzing section to select a second communication device to transfer a session set up with said first client by said session setup section from a plurality of communication devices.

11. Servers each comprising a session transferring section to take over, by the transfer of information about a session setup between a first communication device and a session setup section, being possessed by said session setup section, a session with said first communication device from said session setup section and having a function of rewriting a source address to be transmitted to said first communication device into a system address, in a network system having said system address representing a plurality of servers.

22. The server according to claim 11, wherein said session transferring section provides, when a session between said server and said first communication device is terminated, an instruction for the deletion of an entry corresponding to said session from a converting table of an address in a switching device of a network system.

12. A switching method for a switching system having an address converting section, a session setup section, and a session transferring section, comprising:

a first step of an address converting section selecting an unused address and rewriting an destination address of a packet transmitted from a first communication device into the selected address and sending out a packet having the written address to a network;

a second step of receiving a packet using said selected address as its destination and of said session setup section setting up a session with said first communication device; and

a third step of said session transferring section transferring the setup session to a second communication device.

13. A switching method employed in a switching system having a system address representing a plurality of first communication devices for connecting a second communication device making a request for session using said system address as its destination of a packet to any one of said plurality of first communication devices, comprising:

an address converting step of selecting an additional address being able to be arbitrarily used and rewriting a destination address of a packet received from said second communication device into the selected additional address and sending out said packet having a rewritten address;

a session setting up step of receiving said packet having assigned said additional address using said selected additional address as its destination and setting up a session with said second communication device; and

a session transferring step of transferring information about said set-up session containing said selected additional address to one selected from said first communication devices;

wherein said selected additional address, after said information about said set-up session is transferred, is deleted from addresses of said packet assigned in said session setting up step.

14. A switching method employed in a switching system having a system address representing a plurality of server devices each having a fixed address for connecting a client device making a request for session using said system address as a destination of a packet to any one of said plurality of server devices, comprising:

an address converting step of selecting an unused additional address out of additional addresses being arbitrarily used being different from said fixed address and rewriting a destination address received from said client device into the selected additional address;

a session setting up step of receiving a packet having said unused additional address and using said selected additional address as its destination and setting up a session with said client device; and

a session transferring step of transferring information about the set-up session containing said selected additional address to a selected server device;

wherein said session setup section deletes, after said information about the set-up session is transferred, said selected additional address to make the state usable.

15. A switching method being provided with a system address being set to a local network containing a plurality of server devices each having a fixed address and representing said plurality of server devices for connecting a client device outside said local network making a request for session using said system address as its destination of a packet to any one of said plurality of server devices, comprising:

an address converting step of managing an additional address being able to be arbitrarily used in addition to said fixed address and selecting an unused additional address and rewriting a destination address of a packet received from said client device into the selected additional address;

a session setting up step of receiving said packet having assigned said unused additional address using said selected additional address as its destination and setting up a session with said client device; and

a session transferring step of transferring information about the set-up session containing said selected additional address to the selected server device;

wherein said selected additional address is deleted, after said information about the set-up session is transferred to said selected server device, from said additional address assigned to said session setup section and the state is made to be usable.

16. A switching program to make an address converting section perform a step of selecting an unused address, when a packet destined to a specified address is received from a first communication device, and of rewriting a destination address of said packet destined to said specified address received from said first communication device into the selected address and a step of sending out the packet having the rewritten address to a network.

17. A switching program to make a session setup section perform a step of setting up, a packet destined for an address temporarily assigned is received as a request for new session, a session with a first communication device serving as a source device of packet and a step of transferring the set-up session to a second communication device.

18. A switching system comprising an address converting section to rewrite, when a source address of a packet destined for a specified address from a first communication device is not stored in a converting table, a destination address of a packet into a specified default address and to send out said packet having the written address to a network and to rewrite, when said source address is stored in said converting table, a destination address of a packet in accordance with said converting table and to send out said packet having the rewritten address, a session setup section to receive a packet using said default address as a destination and to set up a session with a first communication device, a session information rewriting section to select an address to be assigned to the setup session and to set the selected address to said converting table, and a session transferring section to transfer said setup session to a second communication device.

19. A switching device having a converting table for address conversion comprising an address converting section to rewrite, when a packet destined for a specified address from a communication device not stored in said converting table is received, a destination address of a packet into a specified default address and to send out said packet having the rewritten address to a network and rewrites, when a packet destined for a specified address from said communication device stored in said converting table is received, a destination address in accordance with said converting table and to send out said packet having the rewritten address.

20. A dispatcher comprising a session setup section to set up, when a packet destined for a specified address is a request for new session, a session with a first communication device being a source of a packet, a session information rewriting section to select an address to be assigned to the setup session from unused addresses and to the selected address to a converting table, and a session transferring section to transfer said setup session to a second communication device.

21. The dispatcher according to claim 20, wherein said session transferring section provides, when a session between said server and said first communication device is terminated, an instruction for the deletion of an entry corresponding to said session.

23. A session switching method for switching from a session between a first communication device and a second communication device to a session between said first communication device and a third communication device, comprising:

a step of a switching device rewriting, when a source address of a packet destined for a specified address from said first communication device is not stored in a converting table in said switching device, a destination address of a packet into a specified default address and sending out said packet having the rewritten address and rewriting, when said source address is stored in said converting table, a destination address of said packet in accordance with said converting table and sending out said packet to a network;

a step of said second communication device receiving a packet using said default address as its destination and setting up a session with said first communication device;

a step of said second communication device selecting an address to be assigned to the setup session and setting the selected address to said converting table; and

a step of said second communication device transferring said setup session to a third communication device.

24. A session transferring method in communication devices comprising:

a step of receiving a packet using a specified default address from a first communication device as its destination and setting up a session with said first communication device;

a step of assigning an address selected from unused addresses to the setup session; and

a step of transferring said setup session as a session between said first communication device and second communication device to said second communication device.

25. A program to make a communication device perform steps of:

receiving a packet using a specified default address from a first communication device as its destination and setting up a session with said first communication device;

assigning an address selected from unused addresses to the setup session; and

transferring said setup session as a session between said first communication and second communication device to said second communication device.