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Description of Connection Types on the FRSM
The following sections describe NIW, SIW, FUNI, and frame forwarding. Topics include translation
and congestion management.
Frame Relay-to-ATM Network Interworking
FR-ATM network interworking (NIW) supports a permanent virtual connection (PVC) between two
Frame Relay users over a Cisco network or a multi-vendor network. The traffic crosses the network
as ATM cells. To specify NIW for a connection, add the connection with a channel type of "network
interworking." For an illustration of a BPX 8620 network with NIW connections, see Figure 6-2.
Figure 6-2
FRAD
(router)
In addition to frame-to-cell and DLCI-to-VPI/VCI conversion, the NIW feature maps cell loss
priority (CLP) and congestion information from Frame Relay-to-ATM formats. Subsequent sections
contain the details. You can modify the CLP and congestion indicators for individual connections.
Congestion Indication for NIW Connections
You can modify the CLP and congestion indicators for individual connections. On the CLI., use the
cnfchanmap command. In the Frame Relay-to-ATM direction, you can configure each Frame
Relay-ATM NIW connection for one of the following CLP-to-DE mapping schemes:
•
DE bit in the Frame Relay frame is mapped to the CLP bit of every ATM cell generated by the
segmentation process.
•
CLP is always 0.
•
CLP is always 1.
In the ATM-to-Frame Relay direction, you can configure each Frame Relay/ATM NIW connection
for one of the following CLP-to-DE mapping schemes:
•
If at least one ATM cell from a frame has CLP=1, the DE field of the Frame Relay frame is set.
•
No mapping from CLP to DE.
Congestion on the Frame Relay/ATM network interworking connection is flagged by the EFCI bit.
The EFCI setting depends on the direction of the traffic. In the Frame Relay-to-ATM direction, EFCI
is always set to 0. In the ATM-to-Frame Relay direction, the FECN bit of the Frame Relay frame is
set if the EFCI field in the last received ATM cell of a segmented frame is set.
BPX 8620 Network with NIW Connections
Frame Relay
DS1
FRSM
MGX 8850
Description of Connection Types on the FRSM
BPX 8620 network
PVCs
MGX 8850
FRSM
Card and Service Configuration 6-23
Frame Relay
DS1
MGX 8850 FRSM
Frame Relay
DS1
FRAD
(router)
FRAD
(router)
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