Method and system for ethernet active-pair detection

1. A method of signaling between Ethernet transceiver link partners along a link, the link including between one to four twisted pair channels, the method comprising:

in an offline mode of operation,

autonegotiating between the link partners during an autonegotiation sequence;

discovering a number of active pairs out of the one to four pairs of twisted pair channels, the discovering including

transmitting a discovery signal from a transmit end of the link on the active pairs,

detecting the transmitted discovery signal at a receive end of the link, the detecting including measuring a power parameter associated with the discovery signal and comparing the measured power parameter to an expected power parameter, the number of active pairs based on a result of the comparing, and

identifying the active pairs based on the detecting;

training the link active pairs to train transceiver operating parameters with a training sequence of symbols; and

in an online mode of operation,

operating the link in a data transfer mode utilizing at least one of the identified active pairs.

2. The method according to claim 1 , wherein the autonegotiating comprises:

advertising support for less than a default configuration of four twisted pair channels.

3. The method according to claim 1 , wherein the autonegotiating comprises:

synchronizing the link partners to carry out the discovering within a same time interval.

4. The method according to claim 1 , wherein utilizing at least one of the identified active pairs comprises:

utilizing a maximum number of the identified active pairs.

5. A system for establishing a link between Ethernet transceiver link partners, the link partners interconnected via one to four twisted pair channels, the system comprising:

one or more circuits of a transceiver operable to autonegotiate between the link partners during an autonegotiation sequence;

one or more circuits of the transceiver operable to discover a number of active pairs out of the one to four twisted pair channels, the one or more circuits operable to discover including

transmit circuitry to transmit a discovery signal from a transmit end of the link on the active pairs,

power measurement circuitry to detect the transmitted discovery signal at a receive end of the link by measuring a power parameter associated with the discovery signal and comparing the measured power parameter to an expected power parameter, the number of active pairs based on a result of the comparing, and

circuitry to identify the active pairs based on the detecting; and

one or more circuits of the transceiver operable to train transceiver operating parameters with a training sequence of symbols.

6. The system according to claim 5 , wherein the one or more circuits of a transceiver operable to autonegotiate between the link partners during an autonegotiation sequence are operable to advertise support for less than a default configuration of four twisted pair channels.

7. The system according to claim 5 , wherein the one or more circuits of a transceiver operable to autonegotiate between the link partners during an autonegotiation sequence are operable to synchronize the link partners to carry out the discovering within a same time interval.

8. The system according to claim 5 , further comprising:

one or more circuits of a transceiver operable to, in an online mode of operation, utilize a maximum number of the identified active pairs during data transfer operations.