Monitoring of connection between an ethernet hub and an end station

• US 6,538,994 B1
• Filed: 04/06/1999
• Issued: 03/25/2003
• Est. Priority Date: 05/20/1998
• Status: Expired due to Fees

• Current Assignee: 3Com Technologies Ltd (HP Inc.)
• Original Assignee: 3Com Technologies Ltd (HP Inc.)
• Inventors: Law, David J., Horspool, Nigel, Cramphorn, Paul, Moran, Paul J.
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Tran, Thien D
• Application Number:
  US09/286,474
• Time in Patent Office: 1,449 Days
• Field of Search: 370/230, 370/231, 370/232, 370/233, 370/234, 370/235, 370/237, 370/238, 370/358, 370/391, 370/395.64, 370/395.65, 370/450, 370/459, 370/465, 370/468
• US Class Current: 370/230
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A data connection between two network stations such as an Ethernet hub and an end station which are both capable of exchanging data at the higher of two rates, the higher rate being selected by an auto-negotiation process, is monitored for the occurrence of error represented by a symbol representing the start of a data packet immediately followed by an idle symbol. The rate of occurrence of such errors is compared against a threshold and the speed of the data connection is downgraded to the lower rate.

Claims

1. A method of controlling the rate of transmission of data between a network station having various ports and another station connected by way of a transmission link to one of said ports, wherein both the said network station and the other station are capable of receiving and transmitting data at any one of a defined plurality of standard data rates, said data rates comprising at least a higher rate and a lower rate, and wherein the said network station includes means for establishing by means of auto-negotiation whether data is to be transmitted between the said network station and the other station at the said higher rate, and further wherein a data connection between the said network station and the other station is maintained by the transmission of a continuous sequence of symbols representing an idle state, said method comprising:

(a) monitoring at the said network station the occurrence of an error represented by a symbol other than an idle state immediately followed by an idle state symbol;

(b) comparing a rate of occurrence of said errors with a threshold; and

(c) forcing the data connection to proceed at the said lower rate if the aforementioned error rate exceeds the threshold.

2. A method according to claim 1 wherein a data packet transmitted from the said other station to the said network station commences with a first predetermined symbol followed by a second predetermined symbol and wherein said network station detects said errors by detecting the occurrence of said first predetermined symbol immediately followed by a symbol representing the idle state.

3. A method of controlling a data rate between a network station having various ports and another station connected by way of a link to one of said ports, wherein both the network station and the another station are capable of receiving and transmitting data at any one of a defined plurality of standard data rates, said data rates comprising at least a higher data rate and a lower data rate, said method comprising:

(a) establishing by way of auto-negotiation between said network station and said another station that data is to be transmitted on the link between the network station and the another station at the higher data rate;

(b) maintaining the link by the transmission of symbols representing an idle state;

(c) monitoring at the network station the occurrence of an error represented by a symbol other than an idle state immediately followed by an idle state symbol;

(d) comparing a rate of occurrence of such errors with a threshold; and

(e) forcing the link to the lower data rate if the rate of occurrence exceeds the threshold.

4. A method according to claim 3 wherein a data packet transmitted from the other station to the network station commences with a first predetermined symbol followed by a second predetermined symbol, and wherein monitoring the occurrence of an error comprises:

detecting the occurrence of said first predetermined symbol immediately followed by a symbol representing the idle state.

5. A method of transmitting data on a link between a network station and a remote station, wherein the network station and the remote station are capable of receiving and transmitting data on the link at any one of a defined plurality of standard data rates, said data rates comprising at least a higher data rate and a lower data rate, the method comprising:

(a) establishing by way of auto-negotiation between the network station and the remote station that data is to be transmitted on the link between the network station and the remote station at the higher data rate;

(b) sending and receiving data on the link at the higher data rate, the data comprising data packets and groups of idle symbols;

(c) monitoring at the network station the occurrence of an error represented by a symbol other than an idle symbol within a group of idle symbols;

(d) comparing a rate of occurrence of such errors with a threshold; and

(e) forcing the link to the lower data rate if the rate of occurrence exceeds the threshold.

6. A method according to claim 5 wherein each data packet commences with a first predetermined symbol followed by a second predetermined symbol and wherein monitoring the occurrence of an error comprises:

detecting the occurrence of said first predetermined symbol immediately followed by an idle symbol.

7. A network station having at least one port capable of receiving and transmitting data on a link between the port and a remote station at any one of a defined plurality of standard data rates, said data rates comprising at least a higher rate and a lower rate, and for transmitting and receiving data composed of defined data packets and groups of idle symbols, said station including:

(a) an auto-negotiation module for establishing on the link that data is to be transmitted on the link between the network station and the remote station at a data rate corresponding to the higher rate; and

(b) a monitoring module which detects errors represented by the occurrence of a non-idle symbol within a group of idle symbols, compares a rate of occurrence of the errors with a threshold and forces the data rate to the lower rate if the rate of occurrence exceeds the threshold.

8. A network station according to claim 7 wherein each data packet commences with a first predetermined symbol followed by a second predetermined symbol, and wherein the monitoring module detects the occurrence of the first predetermined symbol immediately followed by an idle symbol.