Sending Station, Relay Station, And Relay Method

• US 20090245166A1
• Filed: 06/08/2009
• Published: 10/01/2009
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: OKUDA, Masato
• Granted Patent: US 8,509,229 B2
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling

Abstract

In a relay station, a packet fragmented by a sending station is received. The fragmented packet is selectively further fragmented into a plurality of refragmented packets. Identification information (FSN) is added to each of the refragmented packets and to a non-refragmented packet not fragmented. Each of the packets to which the identification information (FSN) has been added is transmitted to a receiving station. This makes it possible to prevent a confliction of information (FSN) between packets due to the packet refragmentation in the relay station.

Claims

1. A relay station for receiving a packet transmitted from a sending station and relaying said packet to a receiving station, comprising:

packet receiver configured to receive a packet fragmented in said sending station;

packet fragmenting unit configured to selectively further refragment said packet received by said packet receiver into a plurality of refragmented packets;

controller configured to add identification information to each of said refragmented packets and to a packet not refragmented in said packet fragmenting unit; and

packet transmitting unit configured to transmit to said receiving station each of said packets to which said identification information has been added by said controller.

2. The relay station as set forth in claim 1, wherein said packet fragmenting unit comprises

a fragmentation determiner that, based on a predetermined reference, determining whether said packet received by said packet receiver is further fragmented into said plurality of refragmented packets, and

a packet refragmenting unit that refragments said fragmented packet if said fragmentation determiner determines that said fragmented packet is further fragmented.

3. The relay station as set forth in claim 2, wherein if a packet size of said fragmented packet received by said packet receiver exceeds a size that is transmittable to said receiving station at that time, said fragmentation determiner determines that said fragmented packet is further fragmented.

4. The relay station as set forth in claim 1, wherein said controller comprises a sequence number assigner for adding a sequence number to said refragmented packet and said non-refragmented packet as said identification information regardless of said refragmentation.

5. The relay station as set forth in claim 4, wherein said controller further comprises a sequence number manager for managing said sequence number according to a connection with said receiving station, and said sequence number assigner adds said sequence number to said refragmented packet and non-refragmented packet of the same connection under management of said sequence number manager.

6. A relay station for receiving a packet transmitted from a sending station and relaying said packet to a receiving station, comprising:

packet receiver configured to receive a fragmented packet which contains a fragment of said packet fragmented in said sending station, and also contains control information representing which part of said packet said fragment belongs to before fragmentation;

packet fragmenting unit configured to selectively further refragment said packet received by said packet receiver into a plurality of refragmented packets;

controller configured to add to said refragmented packets renewed control information which matches with said control information added before the refragmentation, based on said control information; and

packet transmitter configured to transmit said refragmented packets to which said renewed control information has been added, and the packet not refragmented by said packet fragmenting unit, to said receiving station.

7. The relay station as set forth in claim 6, wherein said control information contains information representing any one of four states:

nonfragmentation, first packet, middle packet, and last packet.

8. The relay station as set forth in claim 7, wherein if said control information contained in said fragmented packet received by said packet receiver represents a first packet, said controller adds control information representing a first packet to one of said refragmented packets and control information representing a middle packet to the other;

if said control information contained in said fragmented packet represents a middle packet, said controller adds information representing a middle packet to each of said refragmented packets; and

if said control information contained in said fragmented packet represents a last packet, said controller adds control information representing a last packet to one of said refragmented packets and control information representing a middle packet to the other.

9. A sending station for transmitting a packet to a relay station that receives said packet and relays said packet to a receiving station, comprising:

packet fragmenting unit configured to fragment a packet into a plurality of blocks that are used as a unit of fragmentation in said relay station;

controller configured to add identification information to each of said blocks fragmented by said packet fragmenting unit;

packet packing unit configured to pack some of said blocks to which said identification information has been added; and

packet transmitter configured to transmit the packets packed by said packet packing unit to said relay station.

10. The sending station as set forth in claim 9, further comprising a header assigner for adding header information to said packets packed by said packet packing unit.

11. The sending station as set forth in claim 9, wherein said identification information is a sequence number that is incremented one by one in said blocks.

12. The sending station as set forth in claim 9, wherein said packet packing unit packs blocks that are the same in a connection with said receiving station.

13. A relay station for receiving a packet transmitted by a sending station and relaying said packet to a receiving station, comprising:

packet receiver for receiving as a packet a plurality of blocks which have been fragmented in said sending station, assigned identification information, packed into one, and transmitted by said sending station;

packet fragmenting unit which, if it is necessary to fragment and transmit said packet received by said packet receiver to said receiving station, separates said packet into said plurality of blocks to generate a plurality of fragmented packets; and

packet transmitter configured to transmitting to said receiving station said plurality of fragmented packets generated by said packet fragmenting unit.

14. The relay station as set forth in claim 13, wherein said identification information is a sequence number that is incremented one by one in said blocks.

15. A relay method for use in a relay station that receives a packet transmitted from a sending station and relays said packet to a receiving station, comprising the steps of:

receiving a packet fragmented in said sending station;

selectively further fragmenting said fragmented packet into a plurality of refragmented packets;

adding identification information to each of the refragmented packets and to a non-refragmented packet not fragmented; and

transmitting to said receiving station each of said packets to which said identification information has been added.

16. A relay method for use in a relay station that receives a packet transmitted from a sending station and relays said packet to a receiving station, comprising the steps of:

receiving a fragmented packet which contains a fragment of said packet fragmented in said sending station, and also contains control information representing which part of said packet said fragment belongs to before fragmentation;

selectively further refragmenting said fragmented packet into a plurality of refragmented packets;

adding to said refragmented packets renewed control information which matches with said control information added before the refragmentation, based on said control information; and

transmitting said refragmented packets to which said renewed control information has been added, and a packet not refragmented, to said receiving station.

17. A relay method for a relay station to receive a packet transmitted from a sending station and relay said packet to a receiving station,

wherein said sending station

fragments a packet into a plurality of blocks that are used as a unit of fragmentation in said relay station;

adds identification information to each of said plurality of blocks;

packs some of said blocks to which said identification information has been added; and

transmits the packed packet to said relay station,

and wherein said relay station

receives the packet from said sending station;

if it is necessary to fragment and transmit said received packet to said receiving station, separates said packet into said plurality of blocks to generate a plurality of fragmented packets; and

transmits said plurality of fragmented packets to said receiving station.