PDS Linux Kernel Device Driver is a driver for E1 devices connected via
Ethernet. Currently, it is assumed that only one E1 device is connected
to one Ethernet port: the driver sends messages via broadcast. (Adding
the ability to work via unicast is not difficult, just no one needs it
at the moment.)

The driver allows you to work in the so-called fake mode, in which it
still returns a positive status without receiving a response from the
device. (In configuration mode, data transmission is stateless.) In this
mode, the PDS can be used as a virtual E1 tunnel: for example, it is
useful for automated testing of E1/DAHDI configuration system.

As an add-on, there is also a simple implementation of the Cisco HDLC
Ethernet encapsulation module. Keepalive messages are not supported.