Internet Exchange Points (IXPs) are the backbones of the internet, as they offer easy connectivity between the Autonomous Systems (ASes) of the internet. The looking glass (lg) implementation is a commonly deployed software in the IXPs. They can be used to trace how an IXP can reach any given IP address on the internet. The lg implementations are made public such that anyone can use it to trace how to connect to a given IP address, thus offering an emulation environment to test the connectivity and performance of an IXP for the service providers before committing to use an IXP for their own connectivity needs.
BIX is an IXP based in Bulgaria. You may access the lg of Bulgarian Internet Exchange (BIX) at http://lg.bix.bg/. For example, see the output of the query from your browser: http://lg.bix.bg/?query=summary&addr=216.146.35.35...