SNOOPING IN SAS EXPANDER NETWORKS

• US 20090168654A1
• Filed: 12/28/2007
• Published: 07/02/2009
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Emulex Design & Manufacturing Corp. (Broadcom, Inc.)
• Inventors: MIES, Carl Joseph, Kompella, Murthy, Warren, Bruce Gregory, Steinmetz, Joseph Harold
• Granted Patent: US 9,065,742 B2
• Time in Patent Office: Days
• US Class Current: 370/241
• CPC Class Codes: H04L 43/0876 Network utilisation, e.g. volume of load or congestion level
• CPC Class Codes: H04L 43/12 Network monitoring probes
• CPC Class Codes: H04L 43/18 Protocol analysers
• 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]
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion

Abstract

Snooping in SAS expander networks is disclosed. Ports in a SAS expander may include snoop circuitry and a snoop tap which allows snoop data to be diverted for snooping prior to any significant transformation of the traffic by the regular port logic. Furthermore, the snoop circuitry can receive OOB signaling and convert it to K characters for transmission through the SAS network and subsequent analysis by a protocol analyzer. The ports and cascades in the expander network can be configured to create snoop paths to enable snoop data to be passed through the network to locations where a protocol analyzer can be easily attached. With SAS snoop ports, there is no disruption to the system. Because only a copy of the data is routed to the analyzer, there is no change to the original signal path and latency is identical with or without the analyzer.

Claims

1. A method for remote snooping of traffic in a switch network, comprising:

tapping off snoop data from a first port on a first switch;

routing the snoop data from the first port to a second port on a second switch through one or more wide ports connecting at least the first and second switches; and

providing the snoop data at the second port for analysis.

2. The method of claim 1, the snoop data representing transmit (Tx) and receive (Rx) traffic on the first port, the method further comprising:

configuring the first port as a snoop tap port to tap off the Tx and Rx traffic; and

configuring the second port as a snoop pass-thru port to provide the snoop data at an output of the second port.

3. The method of claim 2, further comprising:

configuring a third port on the first switch and a fourth port on the second switch as snoop pass-thru ports to reserve the third and fourth ports for snoop data.

4. The method of claim 2, further comprising tapping off the Tx and Rx traffic prior to any substantial primitive manipulation, addition of fill words for rate matching, or protocol conversion.

5. The method of claim 2, further comprising configuring the first and second ports by routing a port configuration command through a logical port to a switch processor in each of the first and second switches.

6. The method of claim 1, the snoop data being a representation of out-of-band (OOB) signaling on the first port, the method further comprising:

configuring the first port as a snoop conversion port to detect the OOB signaling and convert the OOB signaling to K characters, the K characters being the representation of the OOB signaling; and

configuring the second port as a snoop reconversion port to regenerate the OOB signaling at the second port from the K characters received at the second port.

7. The method of claim 6, further comprising:

configuring a third port on the first switch and a fourth port on the second switch as snoop pass-thru ports to reserve the third and fourth ports for snoop data.

8. The method of claim 6, further comprising utilizing envelope detection to detect the OOB signaling.

9. The method of claim 6, further comprising configuring the first and second ports by routing a port configuration command through a logical port to a switch processor in each of the first and second switches.

10. The method of claim 1, wherein the switch network is a Serial Attached SCSI (SAS) network and the first and second switches are SAS expanders.

11. A switch for remote snooping of traffic in a switch network, comprising:

a crossbar switch core;

a plurality of ports configured to be selectively connectable to the crossbar switch core, one or more of the ports including

a snoop tap configured for tapping off snoop data from the port, and

snoop logic for enabling the port to be configured for snooping; and

a processor coupled to the crossbar switch core and the plurality of ports for receiving a configuration command through the crossbar switch core to configure one or more of the plurality of ports.

12. The switch of claim 11, the traffic representing transmit (Tx) and receive (Rx) traffic, the switch further comprising a first port configured as a snoop tap port to tap off the Tx and Rx traffic from the first port as the snoop data.

13. The switch of claim 12, further comprising a second port configured as a snoop pass-thru port to pass the snoop data through the second port.

14. The switch of claim 12, further comprising a second port configured as a snoop reconversion port to regenerate the OOB signaling at the second port from the K characters received at the second port.

15. The switch of claim 12, the snoop tap on each port configured for tapping off the Tx and Rx traffic prior to substantial primitive manipulation, addition of fill words for rate matching, or protocol conversion.

16. The switch of claim 12, further comprising a logical port coupled to the processor and the crossbar switch core and configured for providing access to the processor from the switch core.

17. The switch of claim 11, the traffic including out-of-band (OOB) signaling, the switch further comprising a first port configured as a snoop conversion port to detect the OOB signaling and convert the OOB signaling to K characters representing the snoop data.

18. The switch of claim 17, further comprising a second port configured as a snoop pass-thru port to pass the snoop data through the second port.

19. The switch of claim 17, further comprising a second port configured as a snoop reconversion port to regenerate the OOB signaling at the second port from the K characters received at the second port.

20. The switch of claim 17, each port further including an envelope detector to detect the OOB signaling.

21. The switch of claim 17, further comprising a logical port coupled to the processor and the switch core and configured for providing access to the processor from the switch core.

22. The switch of claim 11, wherein the switch is a Serial Attached SCSI (SAS) expander and the switch network is a SAS expander network.

23. The switch of claim 11, wherein the switch forms a part of a switch network.

24. A switch network for enabling remote snooping of traffic, comprising:

a first switch having a first port configured for tapping off snoop data;

a second switch coupled to the first switch through wide ports on the first and second switches, the second switch having a second port configured for receiving the snoop data; and

one or more cascades coupled between the wide ports on the first and second switches and reserved for routing the snoop data from the first port to the second port through the first and second switches.

25. The switch network of claim 24, the snoop data representing transmit (Tx) and receive (Rx) traffic on the first port, the first port having a snoop tap for tapping off the Tx and Rx traffic from the first port as the snoop data, and the second port configured as a snoop pass-thru port to pass the snoop data through the second port.

26. The switch network of claim 25, further comprising:

a third port on the first switch and a fourth port on the second switch, the third and fourth ports forming a part of the wide ports on the first and second switches, respectively, and configured as snoop pass-thru ports to reserve the third and fourth ports for snoop data;

wherein at least one of the cascades is coupled between the third and fourth ports.

27. The switch network of claim 25, wherein the snoop tap is configured for tapping off the Tx and Rx traffic prior to substantial primitive manipulation, addition of fill words for rate matching, or protocol conversion.

28. The switch network of claim 25, each of the first and second switches further comprising a processor accessible through a logical port, the processor programmed for configuring the first and second ports in accordance with a configuration command received through the logical port.

29. The switch network of claim 24, the snoop data comprising out-of-band (OOB) signaling on the first port:

the first port having a snoop tap for tapping off the OOB signaling, and configured as a snoop conversion port to detect the OOB signaling and convert the OOB signaling to K characters; and

the second port configured as a snoop reconversion port to regenerate the OOB signaling at the second port from the K characters received at the second port.

30. The switch network of claim 29, further comprising:

a third port on the first switch and a fourth port on the second switch, the third and fourth ports configured as snoop pass-thru ports to reserve the third and fourth ports for snoop data.

31. The switch network of claim 29, the first port further comprising an envelope detector to detect the OOB signaling.

32. The switch network of claim 29, each of the first and second switches further comprising a processor accessible through a logical port, the processor programmed for configuring the first and second ports in accordance with a configuration command received through the logical port.

33. The switch network of claim 24, wherein the first and second switches are Serial Attached SCSI (SAS) expanders and the switch network is a SAS expander network.