SWITCH S2-2: CRC-4 MULTIFRAME

In framed mode, S2-2 is used for CRC-4 MF. When CRC-4 is enabled, the unit monitors the incoming data stream for CRC-4 errors. It transmits CRC-4 error counts to the transmitting unit.. When using timeslot zero (TS0), excessive errors may cause loss of frame or loss of sync.

If CRC-4

MF is used, both units must be set for set for CRC-4 MF.

Otherwise, the one using CRC-4 MF will detect loss of sync.

S2-2

Option

 

Off

CRC-4

Disabled

On

CRC-4

Enabled

NOTE: When the data rate is set to 2.048Mb/s, then the unit is forced into G.703 mode, and it transmits user data on all 32 time- lots. There is no framing information; therefore, the CRC4 MF (S2-

2)switch is ignored. In all other rate settings, the unit employs G.704 framing; TS0 is reserved for signaling.

SWITCH S2-3: REMOTE DIGITAL LOOPBACK TYPE

The user can set this switch to select the type of remote loop that will be initiated by the Model 2701. If set to V.54, the Model 2701 will initiate a V.54 loop when Remote Loop is selected by the front panel switches. If set to CSU, the Model 2701 will initiate a CSU loop when Remote Loop is selected by the front panel switches.

S2-3

RDL Type

Off

Initiate a V.54 RDL loop when selected

On

Initiate a CSU loopback when selected

SWITCH S2-4: RDL RESPONSE

V.54 and CSU Loopbacks are special in-band loopback facility that sends a pseudo-random pattern over the data stream. This is useful for campus applications when you need to put a remote unit in loopback.

The unit responds to the V.54 loopback command, and the whole process takes only a few seconds to complete. When V.54 Loopback is disabled, the unit will not be able to send or respond to V.54 or CSU loopback commands. The duration of the loopback is limited by the loopback timeout setting.

S2-4

Option

Off

RDL Response Disabled

On

RDL Response Enabled

SWITCH S2-5 TEST MODE REQUEST FROM DTE

Use Switch S2-5 to allow Model 2701RC to enter loopback tests when the DTE raises the appropriate loop request pin.

S1-8 Setting

9

Off

Response to DTE Loopback Request Enabled

On

Response to DTE Loopback Request Disabled

SWITCH S2-6 FRONT PANEL SWITCHES

As the Front Panel Switches may be inadvertently toggled, or in the event that the end-user may not need to use the switches, the installer may disable the front panel switches. Set Switch S2-6 to determine whether the front-panel toggle switches are enabled or disabled.

S2-6

Option

On

Front Panel Switches Enabled

Off

Front Panel Switches Disabled

SWITCH S2-7 VT-100 OR NMS SELECTION

Switch S2-7 selects the configuration mode that the G.703 Access Rack Card uses. When VT-100 is selected, configuration and status can be setup through a VT-100 terminal using a 1001CC. When NMS (network management station) is selected, configuration and status can be setup and maintained through SNMP using a 1001MC. Please refer to the 1001MC user manual when using this mode.

Note: Dip switch configuration can be used regardless of the setting of this switch. The dip switches are enabled through the VT-100 screens, NMS, or by performing a hardware reset.

S2-7

Management Selection

On

NMS control

Off

VT-100 control

SWITCH S2-8 IMPEDANCE

Switch S2-8 is used to select the line build out for the Model 2701RC. When using the 1001RCM11575 (dual BNC) rear card, set S2-8 to OFF. When using a 120 Ohm cable with RJ-45 connectors, set S2-8 to ON.

S2-8

Setting

75 Ohm

OFF

120 Ohm

ON

10