Q-series protocols

Definition of Q-series protocols in The Network Encyclopedia.

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What is Q-series protocols?

Also called Series Q protocols, a set of protocols developed by the International Telecommunication Union (ITU) that includes the following:

  • Q.920/921:
    Specifies the User-Network Interface (UNI) data-link layer for Integrated Services Digital Network (ISDN), including the ISDN D channel’s Link Access Procedure D (LAP-D) data-link protocol.

     

  • Q.922A:
    Specifies the ITU encapsulation method for frame relay networks.

     

  • Q.931:
    Specifies mechanisms for establishing, maintaining, and tearing down ISDN connections. This includes working with connections in the LAP-D data-link protocol, which runs on the ISDN D channel.

     

  • Q.93B:
    The Asynchronous Transfer Mode (ATM) signaling protocol, which specifies mechanisms for establishing, maintaining, and tearing down broadband ISDN (B-ISDN) connections.