What's Happening at SEGGER?

2016 |
Feb. 04
emNet, Press Releases 2016
embOSIP Switchboard

Easily add virtual Ethernet ports to single port MCUs with emNet

TCP/IP stack now offers support for the Tail Tagging feature of Micrel/Microchip Ethernet switches. emNet is the first embedded IP stack to support Tail Tagging.

This enhancement establishes multiple virtual Ethernet ports when only one physical Ethernet port is available on the CPU - by choosing another PHY.

Offering more than one Ethernet port is normally complex, difficult to handle, and most CPUs only have a single port Ethernet controller. It thus requires additional components such as external Ethernet controllers to extend the number of available ports.

Micrel/Microchip has developed switches which are able to expand one Ethernet port of the CPU into 1+n fully independent ports for the network by using the so-called Tail Tagging mode.

Several ports might, for example, be needed when building a router where every port has to be addressed individually. Additionally, multiple ports can be used to create redundant networks, known as multihoming.

Port addressing is done on a pure software basis and is transparent to the outside. The new feature allows every port to have its own assigned MAC-address so that they appear like different physical hosts in a network.

Additionally, SEGGER is offering hardware to evaluate the feature. embOS/IP Switch Board V2 is now available, including an NXP Kinetis K66 CPU, Micrel/Microchip switch PHY KSZ8794CNX with three usable Ethernet ports and an on-board version of SEGGER’s popular J-Link debug probe.

Tail Tagging support, together with a PHY driver, is available as an add-on. The package can be easily evaluated using SEGGER Embedded Studio, even while in evaluation mode.

More information on Tail Tagging support can be found at

The embOS/IP Switch Board is described in detail here: