# US 2021/0243050 A1 · Ethernet link extension method and device

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- Number: US 2021/0243050 A1
- Document ID: US20210243050A1
- Status: Published application
- Kind: A1
- Application number: 17/237,250
- Filed: 2021-04-22
- Published: 2021-08-05
- Earliest claimed: 2018-09-12
- Assignees: Credo Technology Group Limited
- Applicants: Credo Technology Group Limited
- Inventors: Yifei Dai; Haoli Qian; Jeffey Twombly
- Web page: https://patentgrep.com/patent/US20210243050A1

## CPC

- H04L 12/4625: {Single bridge functionality, e.g. connection of two networks over a single bridge}
- H04B 3/46: Monitoring; Testing
- H04L 12/40136: {Nodes adapting their rate to the physical link properties (LAN switches H04L49/351)}
- H04L 12/46: Interconnection of networks
- H04L 12/4633: {Interconnection of networks using encapsulation techniques, e.g. tunneling}
- H04L 45/02: Topology update or discovery
- H04L 49/3054: {Auto-negotiation, e.g. access control between switch gigabit interface connector [GBIC] and link}
- H04W 88/02: Terminal devices
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Ethernet link extension methods and devices provide, in one illustrative embodiment, an Ethernet link extender with physical medium attachment (PMA) circuits each having a transmitter and receiver that communicate with a respective node in a sequence of communication phases. The sequence includes at least an auto-negotiation phase and a subsequent training phase, the phases occurring simultaneously for both PMA circuits. In the auto-negotiation phase, the PMA circuits operate in a pass-through mode, rendering the extender transparent to the two nodes. In the training phase, the PMA circuits operate independently, sending training frames to their respective nodes based in part on received back-channel information and locally-determined training status information. The training phases may be prolonged if needed to provide a simultaneous transition to a frame-forwarding phase of the sequence.

## Claims

### Claim at position 1

-20. (canceled)

### Claim 21

An Ethernet link extension method that comprises,
in a first communications phase for auto-negotiation:
coupling a transmitter of a second PMA (physical medium attachment) circuit to a receiver of a first PMA circuit to retransmit channel signal waveforms received from a first node;
coupling a transmitter of the first PMA circuit to a receiver of the second PMA circuit to retransmit channel signal waveforms received from a second node; and
monitoring spectra of the channel signal waveforms received from at least one of the first and second nodes to detect an end of the auto-negotiation phase; and
in a subsequent frame-forwarding phase:
demodulating communications received from the first node by the receiver of the first PMA circuit to obtain a first digital channel symbol or bit stream;
conveying the first digital channel symbol or bit stream to the transmitter of the second PMA circuit for transmission to the second node;
demodulating communications received from the second node by the receiver of the second PMA circuit to obtain a second digital channel symbol or bit stream; and
conveying the second digital channel symbol or bit stream to the transmitter of the first PMA circuit for transmission to the first node.

### Claim 22 (depends on 21)

The method of claim 21, wherein said coupling of the transmitter of the second PMA circuit to the receiver of the first PMA circuit during the first communications phase is via an on-chip analog signal line.

### Claim 23 (depends on 21)

The method of claim 21, wherein said coupling of the transmitter of the second PMA circuit to the receiver of the first PMA circuit during the first communications phase includes:
digitizing channel signal waveforms received from the first node to obtain received signal samples;
conveying the received signal samples on a bus to the transmitter of the second PMA circuit; and
converting the received signal samples into an analog electrical transmit signal.

### Claim 24 (depends on 21)

The method of claim 21, further comprising adapting a transmit filter in each of the transmitter of the first PMA circuit and the transmitter of the second PMA circuit in accordance with back-channel information received from the first and second nodes, respectively, during the frame-forwarding phase.

### Claim 25 (depends on 21)

The method of claim 21, further comprising generating filter coefficient updates and detecting filter convergence with a filter adaptation circuit in each of the receiver of the first PMA circuit and the receiver of the second PMA circuit.

### Claim 26 (depends on 25)

The method of claim 25, further comprising:
providing back-channel information to the first and second nodes with a training controller in each of the transmitter of the first PMA circuit and the transmitter of the second PMA circuit; and
confirming filter convergence with each of the training controllers only when filter converge is detected by both the receiver of the first PMA circuit and the receiver of the second PMA circuit.

### Claim 27 (depends on 21)

The method of claim 21, wherein each of the first PMA circuit and the second PMA circuit include multiple transmitter-receiver pairs to support multiple communication lanes between the first and second nodes.

### Claim 28

An Ethernet link extender that comprises:
a first PMA (physical medium attachment) circuit having a transmitter and a receiver that communicate in a sequence of phases with a first node, the sequence including at least an auto-negotiation phase and a subsequent frame-forwarding phase; and
a second PMA circuit having a transmitter and a receiver that communicate in said sequence of phases with a second, different node, the phases in said sequence being simultaneous for the first and second PMA circuits,
the transmitter of the second PMA circuit being coupled to the receiver of the first PMA circuit to retransmit to the second node channel signal waveforms received from the first node during the auto-negotiation phase, and to transmit to the second node a first digital channel symbol or bit stream obtained by the receiver of the first PMA circuit demodulating communications received from the first node during a subsequent frame-forwarding phase,
the transmitter of the first PMA circuit being coupled to the receiver of the second PMA circuit to retransmit to the first node channel signal waveforms received from the second node during the auto-negotiation phase, and to transmit to the first node a second digital channel symbol or bit stream obtained by the receiver of the second PMA circuit demodulating communications received from the second node during the frame-forwarding phase.

### Claim 29 (depends on 28)

The extender of claim 28, wherein said coupling of the transmitter of the second PMA circuit to the receiver of the first PMA circuit during the auto-negotiation phase is via an on-chip analog signal line.

### Claim 30 (depends on 28)

The extender of claim 28, wherein said coupling of the transmitter of the second PMA circuit to the receiver of the first PMA circuit during the auto-negotiation phase is via a digital signal bus between an analog-to-digital converter and a digital-to-analog converter.

### Claim 31 (depends on 28)

The extender of claim 28, wherein the transmitter of the first PMA circuit and the transmitter of the second PMA circuit each include a transmit filter adapted in accordance with back-channel information received from the first and second nodes, respectively, during the frame-forwarding phase.

### Claim 32 (depends on 28)

The extender of claim 28, wherein the receiver of the first PMA circuit and the receiver of the second PMA circuit each include a filter adaptation circuit that generates filter coefficient updates and detects filter convergence.

### Claim 33 (depends on 32)

The extender of claim 32, wherein at least one of the transmitter of the first PMA circuit and the transmitter of the second PMA circuit includes a training controller providing back-channel information to at least one of the first and second nodes, and wherein the training controller confirms filter convergence only when filter converge is detected by both the receiver of the first PMA circuit and the receiver of the second PMA circuit.

### Claim 34 (depends on 28)

The extender of claim 28, wherein each of the first PMA circuit and the second PMA circuit include multiple transmitter-receiver pairs to support multiple communication lanes between the first and second nodes.