Beta Draft Confidential
4-48 ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000
Configuring ATM Logical Ports on Frame-based Modules
Defining ATM Network Interworking for Frame Relay NNI Logical Ports
Table 4-19. Add Logical Port: Discard/Congestion Mapping Tab Fields
Field Action/Description
Discard
Priority Egress
Select one of the following options:
Mapped from DE – (default) The value of the Discard Priority bit is used
to set the CLP bit when the frame is segmented into cells. The mapping is
done just before the frame is presented to the hardware for segmentation.
The Discard/ Priority bit is a product of the ingress data stream’s Discard
Priority bit setting and whatever modifications are made to this bit due to
rate enforcement processing.
Always 0 – The value of the CLP bit is always set to zero (0) for all cells
transmitted on this trunk.
Always 1 – The value of the CLP bit is always set to 1 for all cells
segmented from all frames transmitted on this trunk.
Note: Changing the value of this attribute does not admin down the
logical port.
Discard
Priority –
Ingress
Select one of the following options:
Mapped to DE – (default) The value of the CLP bit received in the cells
that make up the ingress frame is transferred directly to the internal
Discard Priority bit. The Discard Priority bit is transferred with the frame
to the egress card for subsequent transmission. If the egress packet format
is Frame Relay, then the Discard Priority bit is included in the Q.922
header as the discard eligible (DE) bit; if the egress packet format is
ATM, then the CLP bit is set from the Discard Priority bit.
Always 0 – The value of the CLP bit is always set to zero (0) for all cells
transmitted on this trunk.
Always 1 – The value of the CLP bit is always set to 1 for all cells
segmented from all frames transmitted on this trunk.
Not mapped – The value of the Discard Priority bit is always set to zero
(0), ignoring the CLP setting received in the frame. This setting is
transferred to the egress card.
Notes: These Discard Priority settings are used by the rate enforcement
and congestion control processing on the egress card. The egress card
may change the Discard Priority bit due to congestion or rate
enforcement.
Changing the value of this attribute does not admin down the logical
port.
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