GigaBlox Nano Rev B: Energy Efficient Ethernet disabled by default
With GigaBlox Nano Revision B, we made a small but important configuration change: Energy Efficient Ethernet (EEE) is now disabled by default.
EEE, also known as IEEE 802.3az, is a power-saving feature for Ethernet links. When enabled, it allows the Ethernet PHY to enter a Low Power Idle (LPI) state during periods of low network activity. The goal is to reduce link power consumption when no data is being transmitted.
In theory, this is a useful feature. In practice, we have found that it can create compatibility issues in some embedded, robotics, industrial, and mixed-vendor Ethernet systems.
EEE can sometimes contribute to issues such as:
- Intermittent link instability
- Unexpected link drops or reconnects
- Added wake-up latency after idle periods
- Packet loss or delayed packets after the link exits Low Power Idle
- Poor compatibility with some PHYs, NICs, routers, switches, or embedded Ethernet controllers
- Hard-to-debug behavior where a link appears normal, but traffic becomes unreliable after idle periods
For many desktop and office networking applications, EEE works fine. However, GigaBlox Nano is commonly used in systems where deterministic behavior, fast link availability, and broad PHY compatibility matter more than saving a small amount of idle link power. Examples include UAVs, mobile robots, embedded vision systems, and compact sensor platforms.
For that reason, we decided that the safest default behavior for GigaBlox Nano is to keep all Ethernet links fully active rather than allowing the PHYs to enter Low Power Idle.
What changed between Rev A and Rev B?
On GigaBlox Nano Rev A, EEE could be enabled by default depending on the switch/PHY configuration.
On GigaBlox Nano Rev B, we added configuration EEPROM support and changed the default configuration so that EEE is disabled by default.
This means Rev B prioritizes link stability and compatibility over the small power saving offered by EEE.
Does this affect devices that were not using EEE?
No.
EEE only comes into play when the link partners support and negotiate EEE operation. If your connected device was not using EEE, then disabling EEE on GigaBlox Nano does not materially change the Ethernet link behavior.
A non-EEE device will continue to operate as a normal 10/100/1000 Mbps Ethernet device. Autonegotiation, link speed negotiation, and normal packet forwarding are unaffected.
The main practical effect is that Rev B avoids entering Low Power Idle, which removes one possible source of link instability in systems where EEE support is incomplete, inconsistent, or poorly handled by the connected device.
Does this reduce performance?
No.
Disabling EEE does not reduce Ethernet throughput. It simply prevents the PHY from entering a low-power idle state between traffic bursts. In fact, for latency-sensitive or compatibility-sensitive systems, disabling EEE can improve practical behavior because the link remains fully awake and ready to transmit.
Does this increase power consumption?
Slightly, in some idle conditions.
EEE is designed to save power during periods of low traffic, so disabling it can increase idle link power compared with a link that successfully uses EEE. However, for GigaBlox Nano’s target applications, we believe the tradeoff is worthwhile: predictable link behavior is more important than a small reduction in idle power.
Summary
GigaBlox Nano Rev B disables EEE by default to improve compatibility and stability across a wider range of embedded Ethernet devices.
This change should not negatively affect systems that were not using EEE. For most users, the change simply means more predictable Ethernet behavior, especially in compact embedded systems where link reliability is critical.