# US 2014/0153401 A1 · Method and System for Symmetric Transmit and Receive Latencies in an Energy Efficient PHY

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- Number: US 2014/0153401 A1
- Document ID: US20140153401A1
- Status: Published application
- Kind: A1
- Application number: 13/908,108
- Filed: 2013-06-03
- Published: 2014-06-05
- Earliest claimed: 2009-06-04
- Assignees: Broadcom Corporation
- Applicants: Broadcom Corporation
- Inventors: Wael William Diab; Scott Powell
- Web page: https://patentgrep.com/patent/US20140153401A1

## CPC

- H04L 12/12: Arrangements for remote connection or disconnection of substations or of equipment thereof
- H04L 43/0852: Delays
- H04L 45/121: by minimising delays
- H04L 47/12: Avoiding congestion; Recovering from congestion
- Y02D 30/00: Reducing energy consumption in communication networks
- Y02D 30/50: in wire-line communication networks, e.g. low power modes or reduced link rate
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

Aspects of a method and system for symmetric transmit and receive latencies in an energy efficient PHY are provided. In this regard, a delay introduced by a PHY of a network device for outbound traffic and a delay introduced by the PHY for inbound traffic may be controlled such that a transmit delay of the network device is equal, within a tolerance, to a receive latency of the network device. The delays may be controlled based on whether one or more energy efficiency features are enabled in the PHY. The delay introduced by the PHY for outbound traffic may be controlled based on an amount of buffered inbound traffic. The delay introduced by the PHY for inbound traffic may be controlled based on an amount of buffered outbound traffic. The delays may be controlled such that said receive latency and the transmit latency are approximately constant regardless of a mode of operation of the network device.

## Claims

### Claim 1

A method performed by a network device, comprising:
modifying, by an energy efficiency control policy module that controls energy efficient network features of a physical layer device of the network device, an amount of delay in a first path through the physical layer device in a first direction, the modified amount of delay reducing a difference between a first amount of latency in the first path and a second amount of latency in a second path through the physical layer device in a second direction.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first path is a transmit path and the second path is a receive path.

### Claim 3 (depends on 1)

The method of claim 1, wherein the first path is a receive path and the second path is a transmit path.

### Claim 4 (depends on 1)

The method of claim 1, wherein the energy efficiency control policy module controls entry by the physical layer device into one of low power idle and sub-rating.

### Claim 5 (depends on 1)

The method of claim 1, wherein the modifying comprises controlling a size of one or more buffers, controlling one or more thresholds of the one or more buffers;
and/or controlling a rate at which data is read out of the one or more buffers.

### Claim 6 (depends on 1)

The method of claim 1, wherein the modifying comprises controlling a delay introduced by the physical layer device for outbound traffic based on an amount of buffered inbound traffic.

### Claim 7 (depends on 1)

The method of claim 1, wherein the modifying comprises controlling a delay introduced by the physical layer device for inbound traffic based on an amount of buffered outbound traffic.

### Claim 8 (depends on 1)

The method of claim 1, wherein the modifying comprises controlling a delay based on a type of traffic.

### Claim 9 (depends on 1)

The method of claim 1, wherein the modifying comprises controlling a delay based on traffic patterns.

### Claim 10 (depends on 1)

The method of claim 1, wherein the modifying comprises controlling an amount of delay of the first path such that the amount of delay of the first path is substantially equal to an amount of delay of the second path.

### Claim 11

A network device, comprising:
one or more circuits and/or processors for use in the network device, wherein the one or more circuits and/or processors are operable to:
modify, based on an energy efficiency control policy that controls energy efficient network features of a physical layer device of the network device, an amount of delay in a first path through the physical layer device in a first direction, the modified amount of delay reducing a difference between a first amount of latency in the first path and a second amount of latency in a second path through the physical layer device in a second direction.

### Claim 12 (depends on 11)

The network device of claim 11, wherein the first path is a transmit path and the second path is a receive path.

### Claim 13 (depends on 11)

The network device of claim 11, wherein the first path is a receive path and the second path is a transmit path.

### Claim 14 (depends on 11)

The network device of claim 11, wherein the energy efficiency control policy controls entry by the physical layer device into one of low power idle and sub-rating.

### Claim 15 (depends on 11)

The network device of claim 11, wherein the one or more circuits and/or processors control a size of one or more buffers, control one or more thresholds of the one or more buffers; and/or control a rate at which data is read out of the one or more buffers.

### Claim 16 (depends on 11)

The network device of claim 11, wherein the one or more circuits and/or processors control a delay introduced by the physical layer device for outbound traffic based on an amount of buffered inbound traffic.

### Claim 17 (depends on 11)

The network device of claim 11, wherein the one or more circuits and/or processors control a delay introduced by the physical layer device for inbound traffic based on an amount of buffered outbound traffic.

### Claim 18 (depends on 11)

The network device of claim 11, wherein the one or more circuits and/or processors control a delay based on a type of traffic.

### Claim 19 (depends on 11)

The network device of claim 11, wherein the one or more circuits and/or processors control a delay based on traffic patterns.

### Claim 20 (depends on 11)

The network device of claim 11, wherein the one or more circuits and/or processors control an amount of delay of the first path such that the amount of delay of the first path is substantially equal to an amount of delay of the second path.