title: When we connect an ethernet device on the network,at what speed it starts communication
body: <p>What steps are performed by ethernet device to connect to a n/w?
  Does it start communication from it's lowest or highest supported speed?</p>
  
  <p>To make it more clear I have following example</p>
  
  <p>If  device A is currently setup at 10Mbps and just connected to N/W router R,which can support both 10Mbps and 100Mbps. Which device(A or R) will communicate first and what speed. If device A, how will router understand the speed of transmission send by device A?</p>