Linux Data Link (LDL)

The ldl(4) driver originally written by Ole Husgaard in 1998 under GPL is distributed with the openss7 package under AGPL3. It provides a non-standard DLPI interface to Linux NET4 devices.

The original ldl(4) driver, written by Ole Husgaard in 1998, was originally a GPL component of the Linux STREAMS (LiS) distribution from about 2.14 (or earlier) forward. The driver was ported to run with Linux Fast-STREAMS (LfS) between 2003 and 2006. In 2009, ldl(4) was moved to the openss7 package, and work started on a new ldl2 driver. Also, proper lli and dlpi drivers were begun.

Currently the ldl(4) driver is in maintenance stage. The only changes made lately to the driver has been to adapt it to newer kernels. Some of the bottom end of the driver is particularly brittle as it relies heavily on Linux kernel internals. If you need a version that works beyond RHEL 5, you may need to contact OpenSS7 Corporation for an update to support your specific distribution and kernel.

The ldl(4) driver requires Linux Fast-STREAMS and is currently packaged with all the necessary dependencies in the openss7 package.

The ldl(4) driver directly connects to the Linux NET4 network device interface at the bottom of a STREAMS pseudo-device driver and presents a non-standard DLPI interface on the upper side of the driver.

The manual page for the ldl(4) driver is contained on the LDL manual pages page.

There is a test program, ldltest, also written by Ole Husgaard in 1998, that was originally distributed with LiS with the ldl(4) driver. This test program has been maintained up to the current release and can be used to exercise the ldl(4) driver and to attempt regression and validation testing.

Because the upper DLPI interface to the ldl(4) driver. This test driver is non-standard, OpenSS7 has not (yet) written a full regression, verification and validation test suite for this driver.

Although the ldl(4) driver data link provider interface is somewhat non-standard, there is a specification for the Data Link Provider Interface (DLPI) as follows:

• Data Link Provider Interface (DLPI)

Code for the ldl(4) dirver can be found in src/drivers/ldl.c in the release or on GitHub. Code for the second attempt at an LDL replacement is in src/drivers/ldl2.c in the release or on GitHub.

Code for the ldltest program can be found in src/tests/ldltest.c in the release or on GitHub.

A number of packages have been released. Since 2009, the Linux Data Link (LDL) driver has been an integral part of the openss7 package.