A concentrator for a local area network with loop topology uses a connector to which a first workstation is connected and a relay contact for switching between a state in which second and third workstations positioned at both sides of the first workstation are connected to each other and another state...http://www.google.ca/patents/US5034738?utm_source=gb-gplus-sharePatent US5034738 - Concentrator for local area network with loop topology
