The Care and Feeding of ISDN4BSD
11 Setting up an	11 Setting up an	11.2 Overview

11.1 Encapsulation Format

This format to transfer IP (Internet Protocol) data via ISDN is not standardized in any way. Just for reference, this is how it looks like:

When ISDN was starting to become available in Germany, the PPP standard was not yet ``born'' and so this format soon became the ``de facto'' standard to interconnect machines via ISDN and IP. It is very easy to setup and handle and has proven to be reliable without the overhead required by PPP, so it is still in use and you'll find it everywhere here.