3Com SuperStack II PathBuilder S330 Reference Manual page 163

Always 1 — Mode 2 mapping, with the CLP field mapped to a constant value
of 1. Mode 2 is an operational method for indicating data congestion to either
the ATM or Frame Relay network. Mode 2 allows for translation between
NLPID and LLC-SNAP encapsulation. It is used when connecting a Frame Relay
device or network to a non-Frame Relay device or network. For example, if the
PathBuilder S330/S310 switch is connecting a router/FRAD over an ATM
network (public or private) and at the other site a router with an ATM
OC3/STM-1 UNI is connected to the WAN network, typically the router
OC3/STM-1 UNI does not support NLPID and requires mode 2 mapping so that
the packet can be encapsulated to LLC-SNAP.
Start/End FR-SSCS DLCI — The starting and ending Frame Relay data link
connection identifiers of the remote ATM Frame Relay host: 16...991.
FECN to EFCI Mapping — Defines the mapping of FECN incoming on Frame
Relay to the outgoing ATM cell PTI congestion indicator.
Direct — Mode 1 mapping; matches FECN to the PTI CN bit. When the serial
port is in this mode, it does not translate between Frame Relay (NLPID)
encapsulation, rather it sends it straight through the ATM network, possibly
onto a Frame Relay network or device.
Always 0 — Mode 2 mapping. This option sets the EFCI field to 'congestion
not experienced.' Mode 2 is an operational method for indicating data
congestion to either the ATM or Frame Relay network. Mode 2 allows for
translation between NLPID and LLC-SNAP encapsulation. It is used when
connecting a Frame Relay device or network to a non-Frame Relay device or
network. For example, if the PathBuilder S330 switch is connecting a
router/FRAD over an ATM network (public or private) and at the other site a
router with an ATM OC3/STM-1 UNI is connected to the WAN network,
typically the router OC3/STM-1 UNI does not support NLPID and requires mode
2 mapping so that the packet can be encapsulated to LLC-SNAP.
DXI Virtual Circuit Parameters If the serial port is configured as a DXI port,
you must set the following virtual circuit parameters in addition to the common
Shaper Number, Priority, and Early Packet Discard parameters:
(DFA) VPI — The virtual path indicator (VPI) number corresponding to the DFA
field: 0...15. This parameter defines the selected VPI for Mapping to/from the Port
card (Router) to the trunk.
(DFA) VCI — The virtual channel indicator (VCI) number corresponding to the DFA
field: 0...63. This parameter defines the selected VPI for Mapping to/from the Port
card (Router) to the trunk.
(DFA) VCI Range — The DXI virtual channel indicator range: 1...64. This
parameter specifies the number of virtual circuits that will be built, starting from
the specified (DFA) VPI and (DFA) VCI, thereby allowing quick input of multiple
virtual circuits. For example, if you enter 1 as the (DFA) VPI, 2 as the (DFA) VCI, and
5 as the (DFA) VCI Range, five virtual circuits will be built, with the following
VPI/VCI combinations: 1/2, 2/3, 3/4, 4/5, and 5/6.
SDLC Virtual Circuit Parameters If the serial port is configured as a SDLC port,
you simply set the common Shaper Number, Priority, and Early Packet Discard
parameters.
Configuring Virtual Circuits 149