Method of transferring packets and router device therefor

• US 20030053414A1
• Filed: 06/19/2002
• Published: 03/20/2003
• Est. Priority Date: 09/03/2001
• Status: Active Grant

• Current Assignee: Alaxala Networks Corporation (Fortinet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Akahane, Shinichi, Sugai, Kazuo
• Granted Patent: US 7,433,301 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• 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 45/28 using route fault recovery
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04Q 11/0071 Provisions for the electrical-optical layer interface
• CPC Class Codes: H04Q 2011/0077 Labelling aspects, e.g. multiprotocol label switching [MPLS], G-MPLS, MPAS
• CPC Class Codes: H04Q 2011/0081 Fault tolerance; Redundancy; Recovery; Reconfigurability

Abstract

With respect to a router in a backup path in an MPLS network adopting a label stack method, it is an object of the present invention to achieve the same quality-guarantee control as the one performed in a current path. In a packet transfer device accommodating first and second output lines, when the first line has a fault, upon a first packet being received, communication quality information in a header of the first packet is copied. Further, a first header containing the copied priority information and a new label is added to the first packet, and a packet to which the first packet is added is outputted to a second output line. When a second packet is received, communication quality information in a header of the second packet is copied, a second header containing the copied priority information and the new label is added to the second packet, and a packet to which the second packet is added is outputted to the second output line.

Claims

1. A method of transferring packets comprising the steps of:

receiving a packet including a header and data, and

transferring the packet to a first or second output line, said header containing a label used for switching the packet and identification information of communication quality;

wherein when the first output line does not have a fault, upon a packet being received, a first label in a first header of said packet is rewritten, and the packet whose label is rewritten is outputted to said first output line; and

wherein when said first output line has a fault, upon a packet being received, identification information of communication quality in the first header of the packet is copied, a second header containing the copied identification information of communication quality and a second label is added to said packet, and a packet to which said second header is added is outputted to said second output line.

2. A method of transferring packets according to claim 1, wherein even when said first output line has a fault, as in the case when the line does not have a fault, upon said packet being received, a label in said first packet head is rewritten.

3. A method of transferring packets according to claim 1, wherein said header is a Shim header described in Request for comments (RFC) 3032, and said identification information of communication quality is a value of an Experimental Use (EXP) field.

4. A method of transferring packets according to claim 3, wherein said first header and said second header are Shim headers described in Request for Comments (RFC) 3032, a value of the Experimental Use (EXP) field in the header of said first packet is copied to the Experimental Use (EXP) field in said first header, and a value of the Experimental Use (EXP) field in the header of said second packet is copied to the Experimental Use (EXP) field in said second header.

5. A method of transferring packets for a packet transfer device which has an associating table for associating a label added to an inputted packet with a label added when the packet is outputted, and switches the inputted packet from an input line to an output line corresponding to the label added to the packet,

wherein a packet in which a first header containing a first label and identification information of communication quality of the packet are added before data, and a second header containing a second label and said identification information of communication quality are added before said first header is received;

and

wherein priority control of the packet transfer is performed according to said identification information of communication quality in said second header.

6. A method of transferring packets according to claim 5, wherein an output label is obtained by searching said table according to said second label, said second label is swapped for said output label, and is outputted to the output line.

7. A method of transferring packets according to claim 5, wherein said second header is removed from said received packet, and the packet whose said second header is removed is outputted to the output line.

8. A method of transferring packets according to claim 5, wherein said first and second headers are Shim headers described in Request for Comments (RFC) 3032, said identification information of communication quality is a value of the Experimental Use (EXP) field of said first header and the value of EXP field of said first header and a value of the EXP field of said second header are equal to each other.

9. A router device receiving a packet containing header information and processing the packet, said header information including a first section containing a label and a second section indicating communication quality of said packet;

the router device comprising

an output line to which the packet is sent and a table to hold a new label corresponding to said first section,

a table search processing section searching said table using said first section as a search key and determining the output line and the new label corresponding to said packet,

an information-in-header extracting section extracting second section of said packet,

an output header generating section generating additional header information to be added to said received packet using the new label determined by said table search processing section and the second section extracted by said information-in-header extracting section,

a line status monitoring section monitoring the status of said output line, and

a control section receiving a notice of failure from said line status monitoring section, and changing contents of said table according to said notice of failure.

10. A router device receiving a packet containing a first header information and a second header information and processing the packet, said first and second header information including a first section containing a label and a second section indicating communication quality of said packet;

the router device comprising

an output line to which the packet is sent and a table holding a new label corresponding to said first section, and

a table search processing section searching said table using said first section of said first header information as a search key and determining the output line and a new label corresponding to said packet;

wherein the router device further rewrites said first header information according to a processing result of said table search processing section, sends it together with said second header information to said output line, and performs priority control of the packet transfer according to the second section of said first header information.