APPARATUS AND METHOD FOR FORWARDING PACKET DATA

• US 20090245258A1
• Filed: 03/17/2009
• Published: 10/01/2009
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kurosaki, Hiroshi, Tomonaga, Hiroshi, Kuwabara, Takashi, Tanaka, Jun
• Granted Patent: US 8,189,589 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 41/0659 by isolating or reconfiguring faulty entities
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/557 Error correction, e.g. fault recovery or fault tolerance

Abstract

An apparatus includes an input part, a plurality of output parts, and a switching part. The input part inputs a packet and builds at least one forwarding data block including a predetermined destination identifier and packet data extracted from the inputted packet. The switching part includes a forwarding destination storing section for storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts, and receives the at least one forwarding data block from the input part, and forwards it to one of the plurality of output parts on the basis of forwarding destination storing section which is updated in response to a change in the operating state of the plurality of output parts.

Claims

1. An apparatus for forwarding packet data, comprising:

a plurality of output parts for outputting a packet;

an input part for inputting a packet, the input part building at least one forwarding data block that includes a predetermined destination identifier and packet data extracted from the inputted packet, wherein the predetermined destination identifier is information identifying one of the plurality of output parts to which the packet data is to be forwarded when the plurality of output parts are in a predetermined operating state; and

a switching part for receiving the at least one forwarding data block from the input part, and forwarding the received at least one forwarding data block to one of the plurality of output parts, the switching part including;

a forwarding destination storing section for storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the at least one forwarding data block including the predetermined destination identifier is to be forwarded;

an updating section for updating the forwarding destination identifier stored in the forwarding destination storing table in response to a change in the operating state of the plurality of output parts; and

a destination converting section for converting a predetermined destination identifier included in the at least one forwarding data block into a forwarding destination identifier associated with the predetermined destination identifier by referring to information stored in the forwarding destination storing section,

wherein the switching part forwards the at least one forwarding data block to one of the plurality of output parts identified by the converted forwarding destination identifier included in the at least one forwarding data block.

2. The apparatus of claim 1, wherein

each of forwarding destination identifiers stored in the forwarding destination storing section is set at a value identical to the corresponding predetermined destination identifier associated therewith when the plurality of output parts is in the predetermined operating state, and

the updating section updates each of the forwarding destination identifiers stored in the forwarding destination storing section when the operating state of the plurality of output parts has changed into another operating state, so that the each of the forwarding destination identifiers identifies one of the plurality of output parts to which the packet data is to be forwarded when the plurality of output parts are in the another operating state.

3. The apparatus of claim 2, wherein

the predetermined operating state of the plurality of output parts is a state in which there exist no failures occurring in the plurality of output parts, and

the another operating state of the plurality of output parts is a state in which there exist some failures occurring in the plurality of output parts.

4. The apparatus of claim 1, wherein

the input part builds, as the at least one forwarding data block, a sequence of forwarding data blocks each having a header field and a packet data field, the header field storing the predetermined destination identifier for the packet data, the packet data field storing a portion of the packet data so that the packet data is restored by combining all of the packet data fields included in the sequence of forwarding data blocks in the order corresponding to the sequence of forwarding data blocks, and sends the sequence of forwarding data blocks to the switching part;

the forwarding destination storing section of the switching part includes a pair of forwarding destination tables each storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the packet data is to be forwarded;

the destination converting section of the switching part includes a table selecting portion for selecting one of the pair of forwarding destination tables on the basis of the operating state of the plurality of output parts, and converts a predetermined destination identifier included in the header field of each of the sequence of forwarding data blocks into the forwarding destination identifier associated therewith by referring to one of the pair of forwarding destination tables selected by the table selecting portion; and

the switching part forwards each of the sequence of forwarding data blocks to the output part identified by the forwarding destination identifier stored in the header field of the each of the sequence of forwarding data blocks.

5. The apparatus of claim 4, wherein

the pair of forwarding destination tables includes a first destination table for storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the packet data is to be forwarded when the plurality of output parts are in a predetermined operating state, and a second forwarding destination table for storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the packet data is to be forwarded when the plurality of output parts are in another operating state different from the predetermined operating state.

6. The apparatus of claim 4, wherein

the input part further provides the header field of each of the sequence of forwarding data blocks with a position indicator indicating a relative position of a forwarding data block within the sequence of forwarding data blocks, and

the table selecting portion of the switching part switches the selection of the pair of forwarding destination tables during the time period after the completion of processing on all of the sequence of forwarding data blocks and before the beginning of processing on a sequence of forwarding data blocks next to be received, so that the switching part forwards all of the sequence of forwarding data blocks to the same output part.

7. The apparatus of claim 6, wherein

the apparatus includes a plurality of input parts each providing a header field of each of the sequence of data blocks with a source identifier identifying one of the plurality of input parts that has built the sequence of data blocks;

and

the table selecting portion of the switching part controls the selection of one of the pair of forwarding destination tables for each of the plurality of input parts, by selecting the same one of the pair of forwarding destination tables for each of the sequence of forwarding data blocks having the same source identifier in the header field thereof, with reference to the source identifier included in the header field of each of forwarding data blocks received from the plurality of input parts, so that the switching part forwards all of the sequence of forwarding data blocks constituting the packet data to the same one of the plurality of output parts.

8. The apparatus of claim 1, wherein

the apparatus includes a plurality of switching parts;

the input part distributes, as the at least one forwarding block, a plurality of forwarding data blocks among the plurality of switching parts; and

each of the plurality of switching parts forwards a forwarding data block received from the input part to one of the plurality of output parts identified by the forwarding destination identifier included in the received forwarding data block.

9. The apparatus of claim 4, wherein

the apparatus includes a plurality of switching parts;

the input part includes a table selecting section for selecting one of the pair of forwarding destination tables, further provides the header field of the forwarding data block with a table identifier identifying one of the pair of forwarding destination tables selected by the table selecting portion, and distributes, as the at least one forwarding data blocks, a sequence of forwarding data blocks among the plurality of switching parts; and

each of the plurality of switching parts converts the predetermined destination identifier included in the header field of a forwarding data block received from the input part into the forwarding destination identifier associated therewith by referring to one of the pair of forwarding destination tables identified by the table identifier included in the header field of the received forwarding data block, and forwards the received forwarding data block to one of the plurality of output parts identified by the converted forwarding destination identifier thereof.

10. The apparatus of claim 4, wherein

the updating section updates, in response to a change in the operating state of the plurality of output parts, one of the pair of forwarding destination tables that is not being selected by the table selecting portion, and further updates the other one of the pair of forwarding destination tables after the table selecting portion has completed the selection of the one of the pair of forwarding destination tables updated by the updating section, so that the pair of forwarding destination tables store the same forwarding destination identifier in association with each of the predetermined destination identifiers.

12. The method of claim 10, wherein

each of forwarding destination identifiers stored in the forwarding destination storing table is set at a value identical to the corresponding predetermined destination identifier associated therewith when the plurality of output parts are in the predetermined operating state, and

each of the forwarding destination identifiers stored in the forwarding destination storing table is updated when the operating state of the plurality of output parts has changed into another operating state, so that the each of the forwarding destination identifiers identifies one of the plurality of output parts to which the packet data is to be forwarded when the plurality of output parts are in the another operating state.

13. The method of claim 12, wherein

the predetermined operating state of the plurality of output parts is a state in which there are no failures occurring in the plurality of output parts, and

the another operating state of the plurality of output parts is a state in which there are some failures occurring in the plurality of output parts.

11. A method for forwarding packet data from an input part to a plurality of output parts, comprising:

providing a forwarding destination storing table for storing, in association with each of a plurality of predetermined destination identifiers, a forwarding destination identifier identifying one of the plurality of output parts, wherein a predetermined destination identifier is information identifying one of the plurality of output parts to which the packet data is to be forwarded when the plurality of output parts are in a predetermined operating state;

inputting a packet via an input part;

building at least one forwarding data block including a predetermined destination identifier and packet data extracted from the inputted packet;

updating the forwarding destination identifiers stored in the forwarding destination storing table in response to a change in the operating state of the plurality of output parts;

converting a predetermined destination identifier included in the at least one forwarding data block into a forwarding destination identifier associated therewith by referring to the forwarding destination storing table; and

forwarding the at least one forwarding data block to one of the plurality of output parts identified by the converted forwarding destination identifier included therein.

14. The method of claim 11, further comprising:

providing, as the forwarding destination storing table, a pair of forwarding destination tables, each storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the packet data is to be forwarded;

building, as the at least one forwarding data block, a sequence of forwarding data blocks each having a header field and a packet data field, the header field storing the predetermined destination identifier for the packet data, the packet data field storing a portion of the packet data so that the packet data is restored by combining all of the packet data fields included in the sequence of forwarding data blocks in the order corresponding to the sequence of forwarding data blocks;

selecting one of the pair of forwarding destination tables on the basis of the operating state of the plurality of output parts;

converting the predetermined destination identifier included in the header field provided for each of the sequence of data blocks into the forwarding destination identifier associated with the predetermined destination identifier by referring to the selected one of the pair of forwarding destination tables; and

forwarding each of the sequence of forwarding data blocks to one of the plurality of output parts identified by the forwarding destination identifier stored in the header field of the each of the sequence of forwarding data blocks.

15. The method of claim 14, wherein

the pair of forwarding destination tables includes a first destination table for storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the forwarding data is to be forwarded when the plurality of output parts are in a predetermined operating state, and a second forwarding destination table for storing, in association with a predetermined destination identifier, a forwarding destination identifier identifying one of the plurality of output parts to which the forwarding data block is to be forwarded when the plurality of output parts are in another operating state.

16. The method of claim 15, further comprising:

providing the header field of each of the sequence of forwarding data blocks with a position indicator indicating a relative position of a forwarding data block within the sequence of forwarding data blocks, and

switching the selection of the pair of forwarding destination tables during the time period after the completion of processing on all of the sequence of forwarding data blocks and before the beginning of processing on a sequence of forwarding data blocks next to be received, so as to forward all of the sequence of forwarding data blocks to the same output part.

17. The method of claim 16, further comprising:

inputting a packet via a plurality of input parts;

providing a header field of each of the sequence of data blocks with a source identifier identifying one of the plurality of input parts via which the packet is inputted;

controlling the selection of one of the pair of forwarding destination tables for each of the plurality of input parts, by selecting the same one of the pair of forwarding destination tables for each of the sequence of forwarding data blocks having the same source identifier in the header field thereof, with reference to a source identifier included in the header field of each of the sequence of forwarding data blocks, so that the switching part forwards all of the sequence of forwarding data blocks constituting the packet data to the same one of the plurality of output parts.

18. The method of claim 14, further comprising:

updating, in response to a change in the operating state of the plurality of output parts, one of the pair of forwarding destination tables that is not being selected; and

updating the other one of the pair of forwarding destination tables after completion of selecting the one of the pair of forwarding destination tables, so that the pair of forwarding destination tables store the same forwarding destination identifier in association with each of the predetermined destination identifiers.