mscAtmIfVccVcdTmTxPacketWiseDiscard 1.3.6.1.4.1.562.36.2.1.114.5.2.2.100.1.76

This attribute specifies whether packet-wise discard functions are to be enabled or disabled in the transmit data direction for this connection. Packet-wise discard functions should only be requested if this connection is transferring AAL5 frame traffic. This attribute is not applicable for Vpts. Packet-wise functions increase the 'goodput' of the link. The transmit packet-wise functions are Early Packet Discard (EPD) and Partial Packet Discard (PPD). EPD allows the connection to discard an entire frame once the transmit queue has reached the EPD threshold. EPD increases the 'goodput' of a link, since discarding an entire frame means that some queue capacity is guarded for some other frame which is already partially transmitted. All cells of the frame are discarded from the Beginning of Message (BOM) cell up to and including the End of Message (EOM) cell. PPD allows the connection to discard the remainder of a cell- forwarded AAL5 frame if one cell of this frame has been discarded. All cells are discarded up to but not including the EOM cell. The PPD function increases the 'goodput' of the link, since cells which are only going to be discarded at the AAL5 reassembly point are not transmitted. On CQC-based ATM cards, the packet-wise discard functions are PPD and EPD. PPD is available at VCC cell-transfer points. PPD is not applicable at frame-cell conversion points, and is not applicable for Vpcs. PPD is configured by this attribute. Packet-wise discard should only be enabled for connections carrying AAL5 segmentation traffic. Setting the value to enabled for any other traffic type may result in all traffic being discarded. On CQC-based ATM FPs, EPD is automatically enabled at frame-to-cell conversion points, independent of the setting of this attribute. On CQC-based ATM cards, at a permanent VCC connection endpoint, this attribute is not applicable and is ignored. If AAL5 segmentation and reassembly has been requested, PPD and Early Packet Discard (EPD) are automatically enabled. On ATM IP cards, packet-wise discard functions include EPD and PPD. PPD and EPD apply to individual VCCs and VCCs within VPCs at all connection points, including tandem VPC connections. Both PPD and EPD are controlled by this attribute. This attribute may safely be set to enabled for any connection (Vcc or Vpc) on ATM IP FPs since they have the ability to automatically detect AAL5-segmented traffic on a connection, and only enable packet- wise discards if AAL5-segmented traffic is detected. When this attribute is set to enabled, packet-wise discard functions are applied to transmit traffic at this connection point. When this attribute is set to disabled, packet-wise discard functions are not applied to transmit traffic at this connection point. At a SPVC origin on a PNNI interface, a value of enabled specifies that frame discard is requested in the backward direction. When this attribute is set to disabled, backward frame discard is not requested in the SPVC call setup. The transmit packet-wise discard functions that are active are visible in the Vcc/Vpc Tm txPacketWiseDiscard operational attribute.