Trocu DP Bidirectional Loopback Support

As an enhancement to automated testing capability, TRDDS eliminates false error indication when invoking NIE, CSU, or DSU loopbacks immediately following release of OCU loopback.

The TROCU DP will execute a bidirectional loopback when performing an OCU loopback at the TROCU DP as shown in Figure 5. If the TRDDS-R detects a bidirectional loopback during power-up synchronization, the TRDDS-R allows data to pass on the four-wire interface by entering into the pass-thru mode. This allows a standard portable DDS test set, connected to the four-wire customer interface of the TRDDS-R, to verify the integrity of the two-wire loop by transmitting a test pattern and examining the returning data for synchronization and errors. The TROCU DP LBK LED will illuminate solid during an OCU loopback. Refer to Figure 6 for an illustration of the bidirectional loopback pass-thru mode.

TROCU DP

Intra-officeCustomer

Bidirectional loopback

Figure 5. OCU Loopback at the TROCU DP

TROCU DP

TRDDS-R

Test Unit

Data

Pass-Thru

Bidirectional

loopback

Figure 6. TROCU DP Bidirectional Loopback

Pass-Thru Mode

If the TROCU DP bidirectional loopback is invoked after the TRDDS-R achieves synchronization, the TRDDS-R will not pass or receive data from the CPE or DDS test set. This is consistent with current DDS testing methods and is referred to as the TROCU DP bidirectional loopback normal mode. For testing purposes, the installer may choose to initiate the TRDDS-R to pass-thru mode. Once the bidirectional loopback is executed in normal mode, unseat and reseat the TRDDS-R and allow the unit to train-up. Once trained, the TRDDS-R will revert to pass-thru mode for further testing. Refer to Figure 7 for TRDDS operation during bidirectional loopback in normal mode.

	TROCU DP
	TRDDS-R
	X	DSU/CSU
	X	DSU/CSU
	X
	Open Loop
	Bidirectional
	loopback

Figure 7. TROCU DP Bidirectional Loopback

Normal Mode

5.REMOTE PROVISIONING AND DIAGNOSTICS

Control Protocol

Remote access to provisioning and status information is accomplished using ADTRAN Digital System 6 Message protocol, defined in Control and Diagnostic Procedures Practice, Section 6032991-6. Digital System 6 is supported by the TPI 108/109 and 105 portable test set and is supported by Hekimian React 2001 Release 1.900 remote test system. The TRDDS network elements comply with ANSI T1.107-1995, “Digital Hierarchy Format Specifications Annex G” which allows remote provisioning, querying, and performance monitoring via inband control of network elements.

NOTE

The REACT 2001 GUI software Release 1.900 supports ANSI T1.107-1995.

Remote access is accomplished using a defined set of inband DS0 byte sequences similar to the latching loopback sequence. Commands issued through the test system are recognized by the individual channel unit, which responds with the appropriate byte sequences. These inband commands may be used to verify options via dialogs with REACT 2001 and

TPI 108/109 test sets. Unit CLEI, serial number, provisioning, and performance information can be retrieved remotely using the Digital System 6 protocol.

Provisioning and Status

All configuration options can be remotely viewed or provisioned. The front panel Remote (REM) LED indicator will Flash during control link establishment and remains ON after the channel unit has been remotely provisioned.

If the channel unit has been remotely provisioned, the operator can alternate between remote configuration

Section 61291006L2, Issue 2

61291006L2-5B