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Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter
Frame Relay Service Modules (FRSMs)
Figure 4-1 BPX 8620 Network with Networking Interworking Connections
Cell Loss Priority and 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 entering 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.
Frame Relay–to–ATM Direction
EFCI is always set to 0.
ATM–to–Frame Relay Direction
If the EFCI field in the last ATM cell of a segmented frame received is set, then FECN of the Frame
Relay frame will be set.
MGX 8220
MGX 8220
FRSM
FRSM
Frame Relay
DS1
Frame Relay
DS1
FRAD
(router)
Frame Relay
DS1
FRAD
(router)
FRAD
(router)
BPX 8620 network
PVCs
IPX
FRP
H8267