CENTRAL HUB in Tree Topology

  Central Hub in a Tree is an ACTIVE HUB
  ACTIVE HUB contains a repeater
  Repeater is a hardware device that regenerates the received bit pattern before
sending them out.
  Repeater strengthens TX. And increases the distance a signal can travel

™  Secondary HUB in Tree Topology

  Secondary Hub in a Tree may be Active or  Passive HUB
  Passive Hub simply provides physical connection between attached devices ™  Advantages of Tree Topology

  Because of Secondary Hub, More devices can be attached to a Central Hub
and therefore increase the distance a signal can travel
  Enables Differentiated Services: Allows to prioritize communication, e.g.
computers attached to one secondary hub can be given priority over others
  Therefore, TIME SENSITIVE data will not have to wait for access to the
network
  Rest of the advantages are almost the same as STAR
  Example Tree Topology: Cable TV

CABLE TV
–Main cable from main office is divided into many
branches and each branch is divided into smaller branches and so on 
–Hubs are used when cable is divided