callbacks over tunnel are slow compared to local callbacks

Products

• DX Unified Infrastructure Management (Nimsoft / UIM)

Issue/Introduction

We are running a script which performs a number of probe callbacks.   When running this script against local hubs (those which are on the same local network, with no tunnels) we find that the scripts execute very quickly, but when running the same script pointed at a hub that is across a tunnel, it is significantly slower.

Can this be improved?

Environment

DX UIM - Any Version
hub with SSL tunnels

Cause

Working as designed.

Resolution

When two local hubs communicate, a local session (called a 'nimsession' in this context) is opened for communication.

When a tunnel is involved, there is a series of "handoffs" - the local nimsession hands off to an external tunnel/SSL session, which in turn hands it over to another tunnel session on the other side, and this is again handed off to a local nimsession on the other end of the communication.

This series of handoffs adds around 300ms of extra latency per tunnel hop and this cannot be sped up.