MAC address extension to maintain router information in source routed computer networks

• US 7,474,660 B1
• Filed: 03/31/1999
• Issued: 01/06/2009
• Est. Priority Date: 03/31/1999
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pearce, Bernie Paul, Cartee, Claude Alan
• Primary Examiner(s): Pham; Chi H.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US09/283,125
• Time in Patent Office: 3,569 Days
• Field of Search: 370/395.3, 370/395.31, 370/395.5, 370/395.51, 370/395.52, 370/395.65, 370/401, 370/402, 370/403, 370/404, 370/405, 370/408, 370/475, 709/223, 709/224, 709/225, 709/237, 709/311, 709/331, 709/332
• US Class Current: 370/395.3
• CPC Class Codes: H04L 12/4625 Single bridge functionality, e.g. connection of two networks over a single bridge
• 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 45/34 Source routing
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 61/103 across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]

Abstract

The invention solves the problem of maintaining Route information Field (RIF) information in a router for populating the RIF field of packets routed by the router, by storing the RIF information with the Layer 2 address in the address binding table. The address binding table establishes a binding between a Layer 2 address and a Layer 3 address of a station. The Layer 2 address in the address binding table is extended to include the RIF information. The address binding table is normally maintained in the router in an architecture which permits rapid access for fast switching such as cut through routing. A separate RIF cache table, requiring a separate time consuming table look-up is thereby avoided. The address binding table is referred to as the Address Resolution Protocol (ARP) Table in IP protocol. The Layer 2 address is extended to include both MAC address and REF information. The RIF information in the Layer 2 field of the ARP table is updated in response to execution of an ARP Explorer protocol by the router. RIF information is read from an ARP Explorer response packet and written into the Layer 2 field of the ARP table. The Layer 2 address, both MAC address and RIF information, is read from the ARP table for use in populating both the destination address field and the RIF field of a routed packet.

Claims

1. A method for routing a source routed packet to a Source Route Bridge (SRB) subnet for a destination station, comprising:

maintaining an address resolution protocol table (ARP table) in a router having an entry for each station on said SRB subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station; and

writing said RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said destination station.

2. The method as in claim 1 further comprising:

populating said RIF information in said ARP table by reading RIF information from a field of an All Routes Explorer (ARE) packet, either a request or response packet.

4. The method as in claim 1 further comprising:

populating said RIF information in said ARP table by reading RIF information from a field of an ARP Explorer packet, either a request or response packet.

5. The method as in claim 1 further comprising:

updating said second field of said ARP table when said router receives an ARP Explorer request packet from one of said stations on said SRB subnet and said request packet contains RIF information.

14. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for an Internet Protocol (IP) communication session.

15. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for an Appletalk communication session.

16. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for a connectionless mode network service communication session.

17. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for a DECnet communication session.

18. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for an IPX communication session.

19. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for a XNS communication session.

20. The ARP table of claim 1 or claim 10, or claim 11, or claim 12, or claim 13 wherein said Layer 3 address further comprises:

an address for a Vines communication session.

21. The method of claim 1 or claim 12, further comprising:

receiving data by a processor, said data received from a network connection for maintaining said ARP table, and

storing said data in a FLASH memory.

3. A method for routing a source routed packet to a Source Route Bridge (SRB) subnet for a destination station, comprising:

maintaining an address resolution protocol table (ARP table) in a router having an entry for each station on said SRB subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station;

writing said RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said destination station; and

populating said RIF information in said ARP table by reading RIF information from a field of an Single Routes Explorer (SRE) packet, either a request or response packet.

6. A method for routing a source routed packet to a Source Route Bridge (SRB) subnet for a destination station, comprising:

maintaining an address resolution protocol table (ARP table) in a router having an entry for each station on said SRB subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station;

writing said RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said destination station; and

transmitting an ARP Explorer request packet upon expiration of an ARP table flush timer, and updating said second field of said ARP table in response to receipt of an ARP Explorer response packet transmitted by a station in response to said ARP Explorer request packet.

7. The method as in claim 6 further comprising:

choosing a time period of four (4) hours for expiration of said ARP table flush timer.

8. A method for routing a source routed packet to a Source Route Bridge (SRB) subnet for a destination station, comprising:

maintaining an address resolution protocol table (ARP table) in a router having an entry for each station on said SRB subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station;

writing said RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said destination station; and

transmitting a validation frame upon expiration of a validation time interval, and in the absence of a response from said validation frame, transmitting an ARP Explorer request packet, and updating said second field of said ARP table in response to receipt of an ARP Explorer response packet transmitted by a station in response to said ARP Explorer request packet.

9. The method of claim 8 further comprising:

choosing a validation time interval of 15 seconds.

10. A router comprising:

an address resolution protocol table (ARP table), said ARP table maintained in said router, said ARP table having an entry for each station on a Source Route Bridge (SRB) subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said station, said entry having a second field containing a Layer 2 address of said station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station, and;

a packet format circuit to write required RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to a destination station on a destination SRB subnet.

22. The router of claim 10 or claim 11, or claim 13, further comprising:

a processor to receive data from a network connection, said data received from a network connection for maintaining said ARP table, and to store said data in a FLASH memory.

11. A router for routing a source routed packet to a Source Route Bridge (SRB) subnet for a destination station, comprising:

means for maintaining an address resolution protocol table (ARP table) in said router having an entry for each station on said SRB subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station, and;

means for writing said RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said destination station.

12. A computer readable device containing a computer program for performing a method of routing a source routed packet to a Source Route Bridge (SRB) subnet for a destination station, comprising:

maintaining an address resolution protocol table (ARP table) in a router having an entry for each station on said SRB subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station, and;

writing said RIF information read from said second field of said ARP table into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said destination station.

13. An ARP table data structure stored in a computer memory of a router, comprising:

an entry for each station on a Source Route Bridge (SRB) subnet to which said router routes packets, said entry having a first field containing a Layer 3 address of said each station, said entry having a second field containing a Layer 2 address of said each station including a physical (MAC) address and Route Information Field information (RIF information) from said router to said each station, said RIF information in said second field of said ARP table used for writing RIF information into a Route Information Field (RIF) in a message packet before routing said message packet to said SRB subnet for said each station.