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IMPVAX is a DEC MicroVAX 3900 running OpenVMS 7.3. It speaks DECnet and Internet Protocol (IP). This VAX is named to honor IMP - the first internet router. It lives inside a SIMH hypervisor running on an AWS EC2 instance in Amazon's Virginia data center.

IMPVAX is a DECnet Phase IV Area Router serving as the United States East gateway to HECnet - the hobbyist DECnet network. It is also a Routing Node for all Digital and non-Digital systems communicating over DECnet at SANYALnet Labs and places where other hobbyists connect from. It runs Process Software's MULTINET to communicate with some DECnet nodes and uplink to HECnet. It additionally uses a VDE (Virtual Distributed Ethernet) switch running on it's host to communicate with other DECnet nodes.

If you want to connect to HECnet via IMPVAX, you can do one of the following things:

  1. Install MULTINET and connect to IMPVAX (A hobbyist license is available as long as you have a OpenVMS hobbyist license from HPE)
  2. Set up a VDE switch and connect to IMPVAX
  3. If you have a Cisco Router for your DECnet nodes, establish a GRE Tunnel over the internet to my Cisco router connected to IMPVAX

In either case, visit the official HECnet web site (or get in touch with me) when you are ready to connect to IMPVAX and join DECnet nodes across the world.

Here are the basic steps to have a SIMH VAX running OpenVMS 7.3 with licenses for OpenVMS and Layered Products.

And here is how to setup a GRE tunnel to transport DECnet over IP.

HECnet members can contact me for an account.

DECnet Node Status

The current status of DECnet nodes belonging to me as well as other folks connecting to HECnet via IMPVAX is usually available via IMPVAX DECnet Status » and should also be available via RAPTOR ALPHASERVER » and QCOCAL VAX »

SANYALnet Labs

That is just a name I have given my disorganized bunch of computers and electronics hobby projects; it is nebulous and does not really mean anything. Equivalent to "junk in the basement."

DECnet - MAC address - SCSSYSTEMID Calculator

Here is a DECnet administrator's tool in javascript: DECnet - MAC address - SCSSYSTEMID Calculator »


The hobbyist servers I play with and the services they provide are listed at my Freeshell / SDF Web Page.

SANYALnet Labs System Monitor: Latest Notification Events


Supratim Sanyal


This is a private hobbyist server with potentially everything being logged. There is absolutely no assurance of any kind whatsoever, no assumptions can be made about any sort of privacy, security, availability and retention of data. This generally applies to all my hobbyist servers mentioned here and elsewhere.

Free counters!