Techniques for using frame deep loopback capabilities for extended link diagnostics in fibre channel storage area networks

• US 10,243,823 B1
• Filed: 02/24/2017
• Issued: 03/26/2019
• Est. Priority Date: 02/24/2017
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Bharadwaj, Harsha, Venugopalan, Nagendran
• Primary Examiner(s): Lee, Chi Ho A
• Assistant Examiner(s): Lee, Andrew
• Application Number:
  US15/442,425
• Time in Patent Office: 760 Days
• CPC Class Codes: H04B 10/077 using a supervisory or additional signal
• CPC Class Codes: H04L 1/243 at the transmitter, using a loop-back
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/0817 by checking functioning
• CPC Class Codes: H04L 43/14 using software, i.e. software packages network security related monitoring H04L63/1408
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

One embodiment is a method including configuring a first network element of a fiber channel (“FC”) network as a generator element, wherein the generator employs a link diagnostic protocol to cause a second network element comprising a peer of the first network element as a reflector element, wherein the first and second elements are connected via a link; entering a first diagnostic phase, wherein in the first diagnostic phase, diagnostic capabilities of the first and second elements are determined; and subsequent to completion of the first diagnostic phase, entering a second diagnostic phase in which a deep loopback test is performed, wherein the deep loopback test comprises a frame level loopback test for exposing an issue in a path between the first and second network elements beyond a Media Access Control (“MAC”) layer.

Claims

1. A method comprising:

configuring a first network element of a fibre channel (“

FC”

) network as a generator element, wherein the generator employs a link diagnostic protocol to cause a second network element comprising a peer of the first network element as a reflector element, wherein the first network element and the second network element are connected via a link;

entering a first diagnostic phase, wherein in the first diagnostic phase, diagnostic capabilities of the first network element and the second network element are determined; and

subsequent to completion of the first diagnostic phase, entering a second diagnostic phase in which a deep loopback test is performed, wherein the deep loopback test comprises a frame level loopback test for exposing an issue in a path between the first network element and the second network element beyond a Media Access Control (“

MAC”

) layer, wherein frames of the deep loopback test are looped back at a crossbar Application Specific integrated Circuit (“

ASIC”

) of the second network element.

2. The method of claim 1, wherein the deep loopback test is performed in addition to other loopback tests.

3. The method of claim 1, wherein the first network element is an F port of an FC switch and the second network element is an N port of a host bus adapter (“

HBA”

).

4. The method of claim 3, wherein frames of the deep loopback test are looped back at an FC driver of the second network element.

5. The method of claim 1, wherein the first network element is an E port of one of a host bus adapter (“

HBA”

) and a first FC switch and the second network element is another E port of a second FC switch.

6. The method of claim 5, wherein the deep loopback is performed on a data path between the first network element and the second network element.

7. The method of claim 5, wherein the deep loopback is performed on a control path between the first network element and the second network element and wherein frames of the deep loopback test are looped back at an FC-2 layer of the second network element.

8. The method of claim 1, wherein the exposed issue comprises at least one of unresponsive driver software, packet descriptor memory corruption, data structure corruption, FC driver memory leaks in an I/O path, large buffer transfer/receive processing hitting boundary conditions, and frame Direct Memory Access (“

DMA”

) memory corrupting frames due to handling a sudden I/O burst.

9. The method of claim 1 further comprising:

determining a latency of the path by comparing a first timestamp of a frame of the deep loopback test corresponding to a time the frame was sent to the second network element with a second timestamp of the frame corresponding to another time the frame was received back from the second network element.

14. The method of claim 1, wherein the exposed issue comprises at least one of unresponsive driver software, packet descriptor memory corruption, data structure corruption, FC driver memory leaks in an I/O path, large buffer transfer/receive processing hitting boundary conditions, and frame Direct Memory Access (“

DMA”

) memory corrupting frames due to handling a sudden I/O burst.

15. The method of claim 1 further comprising determining a latency of the path by comparing a first timestamp of a frame of the deep loopback test corresponding to a time the frame was sent to the second network element with a second timestamp of the frame corresponding to another time the frame was received back from the second network element.

10. One or more non-transitory tangible media that includes code for execution and when executed by a processor is operable to perform operations comprising:

configuring a first network element of a fibre channel (“

FC”

) network as a generator element, wherein the generator employs a link diagnostic protocol to cause a second network element comprising a peer of the first network element as a reflector element, wherein the first network element and the second network element are connected via a link;

entering a first diagnostic phase, wherein in the first diagnostic phase, diagnostic capabilities of the first network element and the second network element are determined; and

subsequent to completion of the first diagnostic phase, entering a second diagnostic phase in which a deep loopback test is performed, wherein the deep loopback test comprises a frame level loopback test for exposing an issue in a path between the first and second network elements beyond a Media Access Control (“

MAC”

) layer, wherein frames of the deep loopback test are looped back at a crossbar Application Specific Integrated Circuit (“

ASIC”

) of the second network element.

11. The media of claim 10, wherein the first network element is an F port of an FC switch and the second network element is an N port of a host bus adapter (“

HBA”

) and wherein frames of the deep loopback test are looped back at an FC driver of the second network element.

12. The media of claim 10, wherein the first network element is an E port of one of a host bus adapter (“

HBA”

) and a first FC switch and the second network element is another E port of a second FC switch and wherein the deep loopback is performed on a data path between the first and second network elements.

13. The media of claim 10, wherein the first network element is an E port of one of a host bus adapter (“

HBA”

) and a first FC switch and the second network element is another E port of a second FC switch and wherein the deep loopback is performed on a control path between the first and second network elements and wherein frames of the deep loopback test are looped back at an FC-2 layer of the second network element.

16. An apparatus comprising:

a memory element configured to store data; and

a processor operable to execute instructions associated with the data;

the apparatus configured for;

configuring a first network element of a fibre channel (“

FC”

) network as a generator element, wherein the generator employs a link diagnostic protocol to cause a second network element comprising a peer of the first network element as a reflector element, wherein the first network element and the second network element are connected via a link;

entering a first diagnostic phase, wherein in the first diagnostic phase, diagnostic capabilities of the first network element and the second network element are determined; and

subsequent to completion of the first diagnostic phase, entering a second diagnostic phase in which a deep loopback test is performed, wherein the deep loopback test comprises a frame level loopback test for exposing an issue in a path between the first and second network elements beyond a Media Access Control (“

MAC”

) layer, wherein frames of the deep loopback test are looped back at a crossbar Application Specific Integrated Circuit (“

ASIC”

) of the second network element.

17. The apparatus of claim 16, wherein the first network element is an F port of an FC switch and the second network element is an N port of a host bus adapter (“

HBA”

) and wherein frames of the deep loopback test are looped back at an FC driver of the second network element.

18. The apparatus of claim 16, wherein the first network element is an E port of one of a host bus adapter (“

HBA”

) and a first FC switch and the second network element is another E port of a second FC switch and wherein the deep loopback is performed on a data path between the first and second network elements.

19. The apparatus of claim 16, wherein the first network element is an E port of one of a host bus adapter (“

HBA”

) and a first FC switch and the second network element is another E port of a second FC switch and wherein the deep loopback is performed on a control path between the first and second network elements and wherein frames of the deep loopback test are looped back at an FC-2 layer of the second network element.

20. The apparatus of claim 16 further configured for determining a latency of the path by comparing a first timestamp of a frame of the deep loopback test corresponding to a time the frame was sent to the second network element with a second timestamp of the frame corresponding to another time the frame was received back from the second network element.