This Cisco ATM Port Adapter supports advanced ATM hardware features such as per-virtual circuit and per-virtual path traffic shaping, as well as all ATM service classes such as real-time variable bit rate (VBR-rt), constant bit rate (CBR), non-real-time variable bit rate (VBR-nrt), available bit rate (ABR), and unspecified bit rate (UBR). The Cisco ATM Port Adapter also supports 8191 ATM virtual circuits.