Dynamic and intelligent buffer management for SAN extension

• US 20060159112A1
• Filed: 01/14/2005
• Published: 07/20/2006
• Est. Priority Date: 01/14/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Amin, Hitesh, Ryle, Thomas Eric, Diab, John, Sundaram, Ganesh
• Granted Patent: US 7,672,323 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04J 2203/0082 Interaction of SDH with non-ATM protocols
• CPC Class Codes: H04J 2203/0098 Traffic aspects, e.g. arbitration, load balancing, smoothing, buffer management
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04J 3/1617 carrying packets or ATM cells
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/35 by embedding flow control information in regular packets, e.g. piggybacking
• CPC Class Codes: H04L 49/90 Buffering arrangements

Abstract

In a network system for transporting GFP-encapsulated Fibre Channel/FICON data across a SONET/SDH transport network between two Fibre Channel/FICON ports, a transport interface for one Fibre Channel/FICON port intelligently allocates the amount of buffers for receiving Fibre Channel/FICON data from the other Fibre Channel/FICON port by determining the latency of travel across the SONET/SDH transport network. The first transport interface inserts a special latency instruction message into the Fibre Channel/FICON data before encapsulation in a GFP frame. After transport across the SONET/SDH network, the receiving second transport interface immediately sends the special latency instruction message back across the SONET/SDH transport network to the first transport interface which times the return of the special latency instruction message. From the time interval, the first transport interface can determine the latency of the SONET/SDH transport network and allocates the amount of buffers appropriately. This latency determination procedure is performed periodically so that the amount of allocated buffers can change as the latency of the SONET/SDH transport network changes.

Claims

1. A method of operating a transport interface for at least one local Fibre Channel/FICON port, said transport interface providing buffers for Fibre Channel/FICON data encapsulated in GFP frames transported over a SONET/SDH network from a remote Fibre Channel/FICON port, said method comprising:

inserting a special latency instruction message into Fibre Channel/FICON data from said at least one local Fibre Channel/FICON port, said Fibre Channel/FICON data encapsulated in a GFP frame for transmission to said remote Fibre Channel/FICON port;

sending said GFP frame over said SONET/SDH transport network to said remote Fibre Channel/FICON port;

timing a return of said special latency instruction message over said SONET/SDH transport network;

determining an appropriate amount of buffers in said transport interface for Fibre Channel/FICON data encapsulated in GFP frames from said remote Fibre Channel/FICON port from said timing step; and

allocating said appropriate amount of buffers in said transport interface for GFP frames from said remote Fibre Channel/FICON port;

whereby sufficient buffering is ensured in said transport interface to provide maximum throughput over said SONET/SDH network and any additional latency due to buffering in said transport interface is reduced.

2. The method of claim 1 wherein said inserting, sending, timing, determining and allocating steps are repeated periodically so that said amount of allocated buffers is adjusted as the latency of GFP frames transported over said SONET/SDH network between said local and remote Fibre Channel/FICON ports changes.

3. The method of claim 2 wherein said inserting, sending, timing, determining and allocating steps are repeated with a period of about 1 second.

4. The method of claim 1 wherein said special latency instruction message is inserted in a Client Payload Information field of a Payload Area of said GFP frame.

5. The method of claim 4 wherein said special latency instruction message includes a latency sequence number to identify one sequence of said inserting, sending, timing, determining and allocating steps from another sequence of said inserting, sending, timing, determining and allocating steps.

6. The method of claim 4 wherein said special latency instruction message includes a special character encoded in a 4-bit mapping of the 64B/65B control characters as Fh.

7. The method of claim 4 wherein said special latency instruction message includes a command to a transport interface for said remote Fibre Channel/FICON port to resend said special latency instruction message back to said transport interface for said at least one local Fibre Channel/FICON port upon receiving said special latency instruction message.

8. The method of claim 1 wherein said determining step comprises looking up said appropriate amount of buffers corresponding to a time interval from said timing step from a table.

9. The method of claim 1 wherein said determining step comprises calculating said appropriate amount of buffers from a time interval from said timing step.

10. In a network system for transporting GFP-encapsulated Fibre Channel/FICON data across a SONET/SDH transport network between first and second Fibre Channel/FICON ports, said first Fibre Channel/FICON port connected to said SONET/SDH transport network through a first transport interface and said second Fibre Channel/FICON port connected to said SONET/SDH transport network through a second transport interface, said first transport interface comprising:

at least one integrated circuit adapted to insert a special latency instruction message into Fibre Channel/FICON data from said first Fibre Channel/FICON port and to encapsulate said Fibre Channel/FICON data in a GFP frame, to send said GFP frame over said SONET/SDH transport network to second transport interface of said second Fibre Channel/FICON port, to time a return of said special latency instruction message over said SONET/SDH transport network, to determine an appropriate amount of buffers in said first transport interface from a time interval of said special latency instruction message to return, and to allocate said appropriate amount of buffers in said first transport interface for GFP frames from said second Fibre Channel/FICON port so that sufficient buffering is ensured in said first transport interface to provide maximum throughput over said SONET/SDH network and any additional latency due to buffering in said transport interface is reduced.

11. The first transport interface of claim 10 wherein said at least one integrated circuit is adapted to insert said special latency instruction message, to encapsulate said Fibre Channel/FICON data in a GFP frame, to send said GFP frame, to time said return of said special latency instruction message, to determine said appropriate amount of buffers and to allocate said appropriate amount of buffers periodically so that said amount of allocated buffers is adjusted as the actual latency of GFP frames transported over said SONET/SDH network between said first and second Fibre Channel/FICON ports changes.

12. The first transport interface of claim 11 wherein said at least one integrated circuit is adapted to insert said special instruction, to encapsulate said Fibre Channel/FICON data in a GFP frame, to send said GFP frame, to time said return of said special latency instruction message, to determine said appropriate amount of buffers and to allocate said appropriate amount of buffers repeatedly with a period of about 1 second.

13. The first transport interface of claim 10 wherein said at least one integrated circuit is adapted to insert said special latency instruction message in a Client Payload Information field of a Payload Area of said GFP frame.

14. The first transport interface of claim 13 wherein said special instruction message includes a latency sequence number to identify one sequence of said inserting, sending, timing, determining and allocating steps from another sequence of said inserting, sending, timing, determining and allocating steps.

15. The first transport interface of claim 13 wherein said special instruction message includes a special character encoded in a 4-bit mapping of the 64B/65B control characters as Fh.

16. The first transport interface of claim 13 wherein said special latency instruction message includes a command to said second transport interface for said second Fibre Channel/FICON port to resend said special latency instruction message back to said first transport interface for said first Fibre Channel/FICON port upon receiving said special latency instruction message.

17. The first transport interface of claim 10 wherein said at least one integrated circuit is adapted to determine said appropriate amount of buffers in said first transport interface from said time interval of return of said special latency instruction message by looking up said appropriate amount of buffers corresponding to said time interval of return of said special latency instruction message.

18. The first transport interface of claim 10 wherein said at least one integrated circuit is adapted to determine said appropriate amount of buffers in said first transport interface from said time interval of return of said special latency instruction message by calculating said appropriate amount of buffers from said time interval of return of said special latency instruction message.

19. In a network system for transporting GFP-encapsulated Fibre Channel/FICON data across a SONET/SDH transport network between first and second Fibre Channel/FICON ports, said first Fibre Channel/FICON port connected to said SONET/SDH transport network through a first transport interface and said second Fibre Channel/FICON port connected to said SONET/SDH transport network through a second transport interface, said first transport interface comprising:

means for inserting a special latency instruction message into said Fibre Channel/FICON data from said first Fibre Channel/FICON port and for encapsulating said Fibre Channel/FICON data in a GFP frame for transmission to said second Fibre Channel/FICON port;

means for sending said GFP frame over said SONET/SDH transport network to said second Fibre Channel/FICON port;

means for timing a return of said special latency instruction message over said SONET/SDH transport network;

means for determining an appropriate amount of buffers in said first transport interface for Fibre Channel/FICON data encapsulated in GFP frames from said second Fibre Channel/FICON port from said timing means; and

means for allocating said appropriate amount of buffers in said transport interface for GFP frames from said second Fibre Channel/FICON port;

whereby sufficient buffering is ensured in said first transport interface to provide maximum throughput over said SONET/SDH network and any additional latency due to buffering in said transport interface is reduced.

20. The transport interface of claim 19 wherein said inserting, sending, timing, determining and allocating means operate periodically so that said amount of allocated buffers is adjusted as the latency of GFP frames transported over said SONET/SDH network between said local and remote Fibre Channel/FICON ports changes

21. The transport interface of claim 20 wherein said inserting, sending, timing, determining and allocating means operate repeatedly with a period of about 1 second.

22. The transport interface of claim 19 wherein said special latency instruction message is inserted in a Client Payload Information field of a Payload Area of said GFP frame.

23. The transport interface of claim 22 wherein said special latency instruction message includes a latency sequence number to identify one sequence of said inserting, sending, timing, determining and allocating operations from another sequence of said inserting, sending, timing, determining and allocating operations.

24. The transport interface of claim 22 wherein said special latency instruction message includes a special character encoded in a 4-bit mapping of the 64B/65B control characters as Fh.

25. The transport interface of claim 22 wherein said special latency instruction message includes a command to said second transport interface for said second Fibre Channel/FICON port to resend said special latency instruction message back to said first transport interface for said first Fibre Channel/FICON port upon receiving said special latency instruction message