Auto-detection of duplex mismatch on an ethernet

• US 6,938,086 B1
• Filed: 05/23/2000
• Issued: 08/30/2005
• Est. Priority Date: 05/23/2000
• Status: Expired due to Term

• Current Assignee: NetApp, Inc.
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Banga, Gaurav
• Primary Examiner(s): Dharia, Rupal
• Assistant Examiner(s): BAUGH, APRIL L
• Application Number:
  US09/578,218
• Time in Patent Office: 1,925 Days
• Field of Search: 709/227, 709/224, 709/228, 709/230, 370/230, 370/276, 370/278, 370/282, 370/296
• US Class Current: 709/227
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols

Abstract

A method and system for auto-detection of communication mismatch, such as in a networking environment. A device using a communication protocol uses a technique for protocol augmentation to determine sufficient information about whether there is a protocol parameter mismatch, and to determine how to adjust its protocol parameters so that the parameter mismatch is obviated. In a preferred embodiment, the protocol includes an Ethernet protocol, and the mismatch includes information about whether devices at ends of a communication link are using half-duplex or full-duplex settings. A first device using the Ethernet generates messages that force a set of second devices using the same Ethernet to generate responsive messages to send to the first device; the first device determines, by examining features of the responsive messages from the second devices, what protocol settings the second devices are using.

Claims

1. A method, including the steps of:

receiving first and second induced messages at a first device from a second device, said first and second induced messages induced by said first device;

sending jam packet messages from said first device to said second device, said jam packet messages interfering with said second device sending said second induced messages;

comparing how many of said first induced messages are received by said first device when said jam packet messages are not present with how many of said second induced messages are received by said first device when said jam packet messages are present; and

determining whether or not a protocol mismatch exists between said first device and said second device based on a result of said step of comparing, said protocol mismatch relates to configuration of communication between said first device and said second device as half-duplex or full-duplex.

2. A method as in claim 1, further comprising the step of adjusting protocol parameters of said first device to match those of said second device responsive to said step of determining.

3. A method as in claim 1, wherein said first device and said second device communicate over an Ethernet connection.

4. A method as in claim 1, wherein at least one of said first device and said second device includes an end-host or a switch.

5. A method as in claim 1, wherein said first message, second message, and jam packet messages are also sent to one or more other devices.

6. A device, comprising:

a communication link to at least a second device;

a processor that executes instructions; and

a memory storing the instructions including the steps of (a) receiving first and second induced messages at a first device from a second device, said first and second induced messages induced by said first device;

(b) sending jam packet messages to said second device, said jam packet messages interfering with said second device sending said second induced messages;

(c) comparing how many of said first induced messages are received when said jam packet messages are not present with how many of said second induced messages are received when said jam packet messages are present; and

(d) determining whether or not a protocol mismatch exists with said second device based on a result of said step of comparing, said protocol mismatch relates to configuration of communication between said device and said second device as a half-duplex or full-duplex.

7. A device as in claim 6, wherein said instructions further include the steps of adjusting protocol parameters of said device to match those of said second device responsive to said step of determining.

8. A device as in claim 6, wherein said device and said second device communicate over an Ethernet connection.

9. A device as in claim 6, wherein at least one of said device and said second device includes an end-host or a switch.

10. A device as in claim 6, wherein said first message, second message, and jam packet messages are also sent to one or more other devices.