looking glass
jargonnetworkingISP & telecom
A public web interface into a network's router, letting outsiders run ping, traceroute, and BGP queries from inside that network.
The courtesy tool of the ISP world: when routing looks wrong, you check how the routes appear from the other side. Debugging asymmetric paths and hijacks without looking glasses would be guesswork - they are peer review for the routing table.
Also known as: BGP looking glass