Techniques are described for discovering switch-to-switch links in a computer network. In general, the techniques recognize that a link exists between a first switch and a second switch when a MAC address is reachable by a first port of the first switch and by a first port of the second switch, two MAC addresses are reachable by a second port of the first switch, one of the two MAC addresses reachable by the second port of the first switch is also reachable by a second port of the second switch, and the other of the two MAC addresses is also reachable by a third port of the second switch. These techniques search for this occurrence by iteratively searching ports of two switches. That is, the techniques iterate over the ports, rather than MAC addresses thereof. In this manner, the techniques efficiently discover switch-to-switch links in a computer network.