Mixing Media-

At times, you might encounter a situation in which the computers in your   office are networked using one type of cable medium, but the network cards do not support that cable medium,  In this situation, it sometimes is easier to purchase transceivers to convert the network cards instead of purchasing new network cards.

Transceivers have two interfaces.  One interface is a BNC connector and the other is an AUI connector.  This enables a network card with an AUI interface to be used on a bus network utilizing BNC connectors.  The transceiver passes information between the two connectors so the AUI type network card can still participate in the network.