Configuring Virtual Circuits 151Virtual CircuitParametersThe following subsections describe parameters you must enter when youconfigure virtual circuits for different port types.Common VIrtual Circuit ParametersThe following parameters are common to most port types:Slot/Port or Group/Card—The slot number, port or IMA group number, and cardtype.Shaper Number—The number corresponding to the SAR shaper you want toassign to this circuit. You define the fifteen available shapers from the MCPUShapers screen. See “Configuring MCPU Shapers” earlier in this chapter, fordetails.Priority—The priority level: high or low (MCPU, OC3/STM-1, QSIM/HSIM/FAM,Ethernet, CBR, VCM); high, medium, low1, or low2 (T1/E1 UNI).Early Packet Discard—Enables (yes) or disables (no) early packet discard. Forevery connection where early packet discard is enabled, a status is kept whenthere is a partial packet for that connection in the queue. Once the queue cell levelexceeds the Congestion On thresholds, only connections with partial packetsalready existing in the queue are allowed in. Cells from other connections aredropped. Once the congestion has subsided to the Congestion Off level, then allremaining connections are allowed.CAUTION: Do not enable early packet discard for AAL1 traffic.MCPU Virtual Circuit ParametersIP Address—The IP address for the PathBuilder S330/S310.Subnet Mask—The subnet mask for the PathBuilder S330/S310.T1/E1 UNI Port Virtual Circuit ParametersReceive VPI/VCI—The VPI/VCI of cells received by the T1/E1 port.Transmit VPI/VCI—The transmit VPI/VCI of cells transmitted by the T1/E1 port.OC3/STM-1 Port Virtual Circuit ParametersReceive VPI—The VPI of cells received by the OC3/STM-1 port.Transmit VPI/VCI—The transmit VPI/VCI of cells transmitted by the OC3/STM-1port.Serial Port Virtual Circuit ParametersYou build connections from the local Ethernet port to a remote Ethernet port byadding Permanent Virtual Circuits (PVCs). These connections allow the packets tobe transmitted through the ATM network to the destination port.The parameters that appear on the Add Virtual Circuit screen vary, depending onthe configuration of the serial port that is being connected: Frame Relay, DXI, orSDLC.The configuration of the card you select on the List Card menu sets the attributeselection for the virtual circuit configuration parameters. If you configure a virtualcircuit and then change serial port attributes—from DXI to Frame Relay or viceversa—the circuit will be deleted.
