Blog by Daniel Bovensiepen

Automatic configuration of Hirschmann switches

10.04.2010 (23 o'clock)

Hirschmann is a german company which is producing quite sophisticated network components. For the networks in our current projects (area of 40km and more than 600 network components) we were using these switches mainly due to the ring protocol from Hirschmann which provides a decent fail over time (less than 50ms). All in all the components we are using (RS20, RS30, Mach 4004 and Power MICE) are industrial quality network components with great performance.

The issue we run into was the deployment of the configuration. Hirschmann provides special tools which are working on layer 2 to configure all of their network components (HiDiscovery Protocol). In fact this is a handy way to configure large networks but for our needs it wasn’t enough. So we decided to script our configuration. We were using telnet and expect to do this but we run into trouble while trying to change the password. The problem was, that our switch software didn’t support the script mode of changing a password (using a scambled password). Only an interactive mode was available and this one failed permanently when triggered by expect.

The solution was to use the “-s” flag to slow down the speed of expect. An argument I didn’t know before but a colleague told me, that this was used in the past also to slow down the communication over very slow connections like modems.