SEGGER’s network software is designed from the ground up for embedded systems. It is renowned for its high-performance and small memory footprint while still providing flexibility and extensibility. It is at the heart of many industrial and IoT applications, and provides support for a wide variety of standard protocols.

emNet has proven its value in numerous customer products and in SEGGER’s own products, such as J-Trace PRO, J-Link PRO, J-Link WiFi, Flasher PRO, Flasher PRO XL and Flasher ARM for almost two decades. More than an IP stack, it is a complete software package designed to meet all network demands including, and especially, the Internet of Things.

By design, emNet supports both internal and external Ethernet MACs (Medium Access Controller), enabling any standard microcontroller to connect to Ethernet. With emNet, even small, ultra low-power microcontrollers with minimal flash memory and no on-chip MAC can be used.

emNet works best with an RTOS to provide efficient and easy to use connection handling. While SEGGER recommends using embOS, support for other RTOSes is available upon request. Using emNet without an RTOS is also possible.

Key features

  • Easy to use
  • Wide variety of upper layer protocols available
  • Standard socket API for user applications
  • Zero-copy supported for ultra-high performance and efficiency
  • Simple compile-time configuration
  • Extensive runtime configuration
  • IEEE 1588 PTP precision time protocol support
  • Works with or without an RTOS
  • Outstanding documentation

World class IP-based communication

In the world of embedded systems, IP based communication lays the groundwork for any modern device. High-layer IoT (Internet of Things) protocols such as MQTT (Message Queuing Telemetry Transport) still rely on the availability of a TCP/IP stack to provide lower layers of communication in standard protocols such as TCP. As an industry-leading IP stack specifically designed for embedded devices, emNet is an ideal choice to provide this component. It is straightforward to configure and integrate and can easily be fine-tuned to the varying requirements and constraints of embedded systems.


emNet combines maximum performance with minimal memory requirements and simple integration without configuration effort. Its design, which specifically targets embedded devices, makes it highly efficient in terms of flash, RAM and packet processing speed. This means that even small, low-frequency microcontrollers deliver excellent network performance.

Built-in UDP flood protection

emNet is designed to use a single task for management and handling of incoming packets. SEGGER’s TCP/IP stack comes with the built-in performance-optimizing feature UDP flood protection which frees up CPU time that can be used for other tasks. It can help to save execution time on incoming data that would be discarded anyhow. Other tasks in the system exist along with emNet and might also use higher priorities than the IP_Task (used for management and processing received packets) to make sure they fulfill their real-time requirements.


emNet supports Ethernet-APL, the standardized Ethernet Advanced Physical Layer for 2-wire data transmission. It enables consistent and fast IP communication over long cable lengths from the field level to the control system, and meets all requirements that are necessary for reliable operation in the field of process plants. Furthermore, Ethernet-APL has been specifically designed for applications in highly explosive environments.


emNet is offered in two different editions: emNet BASE, the stack itself, which includes the most important protocols related to Ethernet communication, and an emNet PRO package, which includes many other features.

Supported protocolsemNet BASEemNet PRO
Device driverOptionalIncluded
ACD (Address Collision Detection)IncludedIncluded
ARP (Address Resolution Protocol)IncludedIncluded
AutoIP IncludedIncluded
DHCP Client (Dynamic Host Configuration Protocol)IncludedIncluded
DNS Client (Domain Name System)IncludedIncluded
ICMP (Internet Control Message Protocol)IncludedIncluded
IPv4 (Internet Protocol v4)IncludedIncluded
IPv6 OptionalOptional
Loopback deviceIncludedIncluded
Multicast (IGMP)IncludedIncluded
RAW socketsIncludedIncluded
TCP (Transmission Control Protocol)IncludedIncluded
UDP (User Datagram Protocol)IncludedIncluded
VLAN (Virtual Local Area Network)IncludedIncluded
Add-onsemNet BASEemNet PRO
DHCP Server (Dynamic Host Configuration Protocol)OptionalIncluded
mDNS serverOptional Included
NetBIOS name serviceOptionalIncluded
NTP clientOptionalIncluded
PPP / PPPoEOptionalOptional
PTP OC clientOptionalOptional
SNTP clientOptionalIncluded
Tail taggingOptionalOptional
WiFi support[1]IncludedIncluded
Related software productsemNet BASEemNet PRO
emFTP client (FTP client)OptionalOptional
emFTP server (FTP server)OptionalIncluded
emMQTT (MQTT client)OptionalIncluded
emNet CoAP client / serverOptionalIncluded
emNet SMTP clientOptionalIncluded
emNet SNMP agentOptionalOptional
emNet WebSocket client / serverOptionalIncluded
emWeb (web server)OptionalIncluded

[1] WiFi driver required

Depending on the engineer’s needs, there are several protocols available as add-ons. emNet PRO bundles a device driver, web server functionality, SMTP email sender, plus more to satisfy a broad spectrum of use cases in an attractive package.


The network stack emNet has an extensive list of supported devices with its set of drivers. The few existing hardware dependencies are handled in a single place. Switching hardware is an effortless task on the software side of things. If a controller has not made it to the list, chances are good, that support can be derived from currently available drivers.

PHY compatibility

emNet provides support for virtually any Ethernet PHY transceiver due to its flexible PHY driver layer. Included with emNet is a generic PHY driver that is compatible with almost all single port PHYs on the market that follow the IEEE 802.3u standard. Support for other PHY-like devices such as Ethernet switches is also possible.


emNet is available under various Embedded Software License models and delivered in source code packages. With a wide range of licensing options, emNet can fulfill commercial requirements as well as technical requirements. All licenses are one-time payments. emNet is royalty-free and not subscription-based. This makes the software a part of the equipment expenses, keeping the costs static.

* Applies to second seat/product and all additional seats/products of the Single Product License and Single Developer License.