Definition of balun in The Network Encyclopedia.

What is BALUN (in computer networking)?

Stands for bal anced un balanced. A device used to connect balanced lines and unbalanced lines. Balanced and unbalanced lines have different electrical characteristics. A balun matches these characteristics by providing impedance transformation between the two different lines.

Baluns can be used for various types of connections between different wiring systems:

  • Twisted-pair cabling to coaxial cabling:
    Typically used for connecting 10BaseT networks with 3270 equipment running on coax or twinax networks


  • Twisted-pair cabling to token ring cabling:
    Used for matching token ring Type 1 cabling to standard unshielded twisted-pair (UTP) cabling to connect 10BaseT or faster hubs or adapters with RJ-45 ports into a token ring network


  • Asynchronous Transfer Mode (ATM) cabling to token ring cabling:
    Used for connecting token ring networks to high-speed ATM hubs in campus backbone networks