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Frame Relay Network Interworking (FRF.5) 183
Model 3086 G.SHDSL Integrated Access Device User Guide F • Interworking Functions Information
Port Level Configuration Options:
Ports are used to define the lower level Interworking Functions. The port configuration will define the follow-
ing variables:
• VPI—Virtual Path Identifier: ATM side Virtual Path Identifier for the specified connection.
• VCI—Virtual Channel Identifier: ATM side Virtual Channel Identifier for the specified connection
• DE Mapping: The DE Mapping variable is used to determine how the Frame Relay DE field (Discard Eli-
gibility) will be mapped to the ATM CLPI (Cell Loss Priority Indication). This variable is only used in the
Frame Relay to ATM mapping direction. Note that the DE bit from the core Q.922 (Frame Relay) packet
will always be copied unchanged into the FR-SSCS PDU header cell. The following options define how the
DE will be mapped to the ATM CLPI bit:
– Always_zero: All ATM cells will have the CLPI field set to a constant value of 0.
– Always_one: ATM: All ATM cells will have the CLPI field set to a constant value of 1.
– Convert: The system will convert the DE field received from the Frame Relay packet into the CLPI field
of the outgoing ATM cell that is generated by the segmentation process.
• CLPI Mapping: The CLPI Mapping variable is used to determine how the ATM CLPI (Cell Loss Priority
Indication) bit in the ATM cell will be mapped to the DE (Discard Eligibility) bit of the resulting Frame
Relay packet. There are two options available.
– Fr_sscs_only: The FR-SSCS removed from the ATM header PDU is used to set the DE bit in the out-
put Frame Relay packet. The CLPI bit from the ATM cell is ignored.
– Fr_sscs_and_clpi: Both the DE bit from the ATM header PDU and the CLPI bit from the received
ATM cells are used to determine the output state of the resulting Frame Relay packet. The following
table defines how .
• Multiplexing Mode: The MuxMode variable allows multiple channels to be multiplexed onto a single port.
A port is defined by its’ VPI/VCI of the ATM rfc1483 data path. Channels are defined by their Frame Relay
DLCI. Thus, the multiplexing mode will allow multiple Frame Relay channels to be transported over a sin
-
gle ATM VPI/VCI link. There are two options available.
– Mux_many_to_one: The “many to one” option allows multiple DLCI channels to be transported over
a single ATM rfc1483 connection. Note that if the MuxMode is not set to “many to one” trying to add
multiple DLCI connections will result in errors.
– Mux_one_to_one: The “one to one” option notifies the system that there will be a one to one mapping
between a single ATM port VPI/VCI and a single Frame Relay DLCI.
• FRN Name: Allows the user to name the FRN port. This is helpful when viewing multiple connections to
determine which VPI/VCI is associated with each port.
CLPI received from ATM cell DE from FR-SSCS of ATM cell Outgoing DE bit of FR Packet
0 0 0
1 X 1
X 1 1