Since I’m a big fan of OTV (Overlay Transport Virtualization) – really, really good technology – I play with it from time to time, both, labbing and configuring production environments. There are many guides on cisco.com and other blogs on how to configure OTV on ASR1000, but they all seem to be very basic. That basic configuration is not enough to run OTV, so, I would like to share my findings, which make OTV to work faster and to be more reliable (thank you goes also to Cisco TAC for pointing out few things). I want to focus on a special-case scenario, which is quite popular (at least what I observe on our local market), but makes OTV a little complicated to configure. It’s about running OTV in a “square” topology, where there are four ASRs connected to each other back-to-back, and unicast adjacency servers are used, like depicted on the below diagram.