Patton electronics ipRocketLink IAD 3086, Руководство пользователя

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Frame Relay Service Interworking (FRF.8) 177
Model 3086 G.SHDSL Integrated Access Device User Guide F • Interworking Functions Information
• Always_one:
– Frame Relay: All Frame Relay packets will have the DE field in the header set to a constant value of 1.
– ATM: All ATM cells will have the CLPI field set to a constant value of 1.
• Convert:
– Frame Relay to ATM Direction: The system will convert the DE field received from the Frame Relay
packet into the CLPI field of the outgoing ATM cell.
– ATM to Frame Relay Direction: The system will convert the CLPI bit received from the ATM cells into
the DE field of the outgoing Frame Relay packet.
FECN Mapping
The FECN Mapping variable is used to determine how the Frame Relay FECN (Forward Explicit Congestion
Notification) bit will be mapped to the ATM EFCI (Explicit Forward Congestion Indication) bit and vise
versa. The following options are available:
• Always_zero:
– Frame Relay: All Frame Relay packets will have the FECN bit in the header set to a constant value of 0.
– ATM: All ATM cells will have the EFCI bit set to a constant value of 0.
• Always_one:
– Frame Relay: All Frame Relay packets will have the FECN bit in the header set to a constant value of 1.
– ATM: All ATM cells will have the EFCI bit set to a constant value of 1.
• Convert:
– Frame Relay to ATM Direction: The system will convert the FECN bit received from the Frame Relay
packet into the EFCI bit of the outgoing ATM cell.
– ATM to Frame Relay Direction: The system will convert the EFCI bit received from the ATM cells into
the FECN bit of the outgoing Frame Relay packet.
Translation Mode:
The Translation Mode variable defines the encapsulation mechanism that will be required to convert the ATM
cells (encapsulated per RFC1483) to the Frame Relay packets (encapsulated per RFC1490) and back. This is
required because ATM and Frame Relay encapsulate packets in different formats as defined by their respective
RFC. There are two options available for the Translation Mode setting within the Model 3086 as defined below:
• Translate: When the connection channel is set to translate, the IWF converts between Frame Relay encap-
sulated packets and the ATM encapsulated cells. This conversion is performed by inspecting each packet/
cell and determining the PID (Protocol Identification) field within the packet. Using this information, the
packet/cell is routed through an encapsulation conversion utility that creates the encapsulation required for
the destination network. The Model 3086 supports all 22 encapsulation types as defined by the FRF.8.1