what is vpi and vci

Figure: VPI/VCI

• A VPI identifies a unidirectional transport of ATM cells belonging to a bundle of virtual channels
• A VCI describes a unidirectional transport of ATM cells
• 8 bits for VPI and 16 bits for VCI (at the UNI) are used for routing purposes
• Assignment of VPI/VCI is done by:
  • The network
  • The user
  • Negotiation between the user and network (signalling)
  • Standardization (Preassigned VCI/VPI values e.g., unassigned cell, etc.)