Why Is Linux Dropping DECnet Support? A Look at Legacy Network Protocols

Microsoft kernel engineer Stephen Hemminger recently suggested removing the DECnet protocol handling code from the Linux kernel.

The timing is ironic, coming just two weeks after VMS Software Inc announced the release of OpenVMS 9.2.

The last maintainer of the DECnet code, Red Hat’s Christine Caulfield, marked it as an “orphan” back in 2010.

In practice, this kernel change is unlikely to inconvenience many users.

VMS is effectively the last mainstream operating system still using DECnet, although it has supported TCP/IP for a long time.

Historically, DECnet was a major network protocol; TCP/IP did not become dominant until the mid‑1990s.

The Linux kernel has historically supported a variety of network protocols.

In 2018, the same Hemminger removed the final remnants of the Novell IPX protocol (and its partner SPX) from the kernel, a protocol that had been obsolete since 2002.

IPX/SPX formed the communication stack for Novell NetWare servers and was the default protocol in Windows for Workgroups 3.11 and Windows NT 3.1, with TCP/IP only an optional add‑on.

Linux still retains support for classic Mac OS’s native network language AppleTalk, which Apple removed from macOS 10.6 “Snow Leopard” onward.

DECnet was once a very important protocol; DEC provided a client stack called PathWorks that let DOS, Windows, and Mac clients connect to VAX servers for file, print, terminal, and X11 services, aiming for a worldwide WAN based on DECnet.

The era of protocol wars has finally ended.