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Cisco MGX 8230 Edge Concentrator Installation and Configuration
Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001
Chapter 2 Module and Service Descriptions
Frame Relay Service Modules
Frame Relay-to-ATM Network Interworking
Frame Relay-to-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 2-12
.
Figure 2-12 BPX 8620 Network with NIW Connections
Congestion Indication for NIW Connections
In addition to frame-to-cell and DLCI to VPI/VCI conversion, the network interworking feature maps
cell loss priority (CLP) and congestion information from Frame Relay to ATM formats. The CLP and
congestion indicators can be modified for individual connections using the cnfchanmap command.
Frame Relay–to–ATM Direction
Each Frame Relay/ATM network interworking connection can be configured as one of the following DE
to CLP 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.
ATM–to– Frame Relay Direction
Each Frame Relay/ATM network interworking connection can be configured as one of the following
CLP to DE mapping schemes:
•
If one or more ATM cells belonging to a frame has its CLP field set, the DE field of the Frame Relay
frame will be set.
•
No mapping from CLP to DE.
Congestion Indication
Congestion on the Frame Relay/ATM network interworking connection is flagged by the EFCI bit. The
setting of this feature is dependent on traffic direction, as described below.
MGX 8850
MGX 8850 FRSM
FRSM
Frame Relay
DS1
Frame Relay
DS1
FRAD
(router)
Frame Relay
DS1
FRAD
(router)
FRAD
(router)
BPX 8620 network
PVCs
FRSM
MGX 8430
17908