Zhone 2000 用户指南

If you select “0” or “1”, the DE field in the Q.922 core frame is copied 

unchanged into the DE field in the FR-SSCS header and the ATM Cell Loss 
Priority (CLP) of every ATM cell generated by the segmentation process of 
that frame will be set to a constant value (either 0 or 1).
If you select “B” (refer to the menu below), the Discard Eligibility (DE) field 

in the Q.922 core frame is copied unchanged into the DE field in the FR-
SSCS header and is mapped to the ATM Cell Loss Priority (CLP) of every 
ATM cell generated by the segmentation process of that frame.

If you select “A”, no mapping is performed from the ATM layer to the Q.922 

core layer. The FR-SSCS DE field is copied unchanged to the Q.922 core 
frame DE field independent of CLP indication(s) received at the ATM layer.
If you select “B”, then if one or more ATM cells belonging to a frame has its 

CLP field set to one or if the DE field of the FR-SSCS PDU is set to one, the 
IAD will set the DE field of the Q.922 core frame.

If you select FRF8 from the Available Interworking Types menu (Figure 4.93), the menu below will be displayed.

The selection of one of these options will determine how upper layer user 
protocol encapsulation is handled. If you select “T”, the FRF.8 Interworking 

function maps between the two encapsulations, translating between RFC 1490 
and RFC 1483. If you select “F”, there is no translation of the data. It is 

transported transparently between frame Relay DLCI and the ATM PVC. The 
IAD forwards encapsulations unaltered; no mapping or fragmentation/
reassembly is performed on the data.