Advanced ethernet auto negotiation

• US 6,580,697 B1
• Filed: 09/21/1999
• Issued: 06/17/2003
• Est. Priority Date: 09/21/1999
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Yuen, Michael, Gardner, Steven Lyle, Hiscock, James Scott
• Primary Examiner(s): Rao, Seema S.
• Assistant Examiner(s): ABELSON, RONALD B
• Application Number:
  US09/400,424
• Time in Patent Office: 1,365 Days
• Field of Search: 370/465, 370/445, 370/296
• US Class Current: 370/296
• CPC Class Codes: H04L 12/40136 Nodes adapting their rate to the physical link properties LAN switches H04L49/351
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 49/3054 Auto-negotiation, e.g. access control between switch gigabit interface connector [GBIC] and link
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/55 Prevention, detection or correction of errors
• CPC Class Codes: H04L 5/1446 of transmission speed

Abstract

A port on a network device engages in auto-negotiation on a network link during a first operational state to select a transmission mode, either half duplex or full duplex. If half duplex operation is selected, the port commences half duplex operation in a second operational state. During the second operational state, the link is monitored for an error condition indicating that another network device attached to the link may not be operating in a half duplex manner. This error condition includes the occurrence of excessive collisions or late collisions. When the error condition is detected, the port commences full duplex operation in a third operational state, based on the presumption that device at the other end of the link may be configured for fixed full duplex operation. If proper operation ensues, the port remains configured for full duplex transmission. Because the presumption may be incorrect, the link is monitored during the third operational state for a second error condition indicating that transmissions by the network device may be interfering with transmissions by the other network device. Examples of the second error condition include excessive frame check sequence errors and an excessive number of abnormally truncated messages. If such a second error condition occurs, the port is disabled in a fourth operational state and the condition is reported to higher-level operating software. Repeated attempts at normal operation may follow, with further monitoring that may result in shutting down the port if normal operation cannot be achieved.

Claims

1. A method of configuring a port on a network device, comprising:

during a first operational state, engaging in an auto-negotiation protocol on a network link attached to the port;

as a result of engaging in the auto-negotiation protocol on the network link, entering a second operational state in which the port is operated in a half duplex manner;

during the second operational state, monitoring the link for a first error condition indicating that another network device attached to the link may not be operating in a half duplex manner;

upon detecting the first error condition in the second operational state, entering a third operational state in which the port is operated in a full duplex manner;

during the third operational state, monitoring the link for a second error condition indicating that the other network device may not be operating in a full duplex manner and in the absence of the second error condition continuing to operate the port in a full duplex manner.

2. A method according to claim 1, wherein monitoring the link for the first error condition comprises:

counting late collisions and the total number of collisions occurring on the link over a predetermined interval; and

comparing the total and late collision counts with respective threshold values.

3. A method according to claim 1, wherein monitoring the link for the second error condition comprises:

counting the number of runt messages and messages having frame check sequence errors received on the link over a predetermined interval; and

comparing the counts of runt messages and messages having frame check sequence errors with respective threshold values.

4. A method according to claim 1, further comprising:

upon detecting the second error condition in the third operational state, entering a fourth operational state in which the port is at least temporarily disabled.

5. A method according to claim 1, further comprising:

upon detecting the second error condition in the third operational state, entering a fourth operational state in which the port is disabled; and

after a predetermined delay period has passed during the fourth operational state, re-entering the first operational state so as to re-enable the link and repeating the operations of claim 1 on the link as re-enabled.

6. A method according to claim 5, wherein during successive repetitions of the fourth operational state, progressively greater predetermined delay periods are allowed to elapse before re-entering the first operational state.

7. In a network having a first device coupled to a second device over a network link, wherein the first device is operative to communicate over the link in a full duplex manner and the second device is capable of employing auto negotiation so as to operate in either a full duplex manner or a half duplex manner, a method of configuring the second device, comprising:

operating the second device in a half duplex manner;

while operating the second device in a half duplex manner, monitoring the communication between the first and second devices for a first error condition;

upon detecting the first error condition, operating the second device in a full duplex manner;

while operating the second device in the full duplex manner, monitoring the communication between the first and second devices for a second error condition; and

in the absence of the second error condition, continuing to operate the second device in a full duplex manner.