ADTRAN 4200659L2 User Manual
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Chapter 6 Diagnostics

The DIAGNOSTICS menu shown inFigure 6-1 allows you to initiate loopback tests from the MX2800STS-1.From this menu, selectVT/PORT orSTS-1.Once this selection is made, a second menu displays the types of tests available.

Descriptions and testing diagrams of the loopback tests are provided in the following portions of this chapter:

VT/Port Loopbacks on page 6-2

STS-1 Loopbacks on page 6-8

Figure 6-1.Diagnostics Menu

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Chapter 6. Diagnostics

VT/PORT LOOPBACKS

After you select the number that corresponds with the line you want to test, the menu in Figure 6-2 appears. The number selected(1-28)refers to the VT number. The Port (T1/E1) that will be tested is the port mapped to the selected VT number. The sections following the figure provide descriptions and illustrations of the testing options. Select1-DATA MODE to end a test in progress.

Figure 6-2.VT/Port Diagnostics Menu

Tributary

A TRIBUTARY loopback loops the selected VT/Port back to the network(STS-1).The T1/E1 is looped back through theSTS-1mapper. During this loopback, the correspondingDSX-1/E1input is overwritten by the outgoingDSX-1/E1signal. SeeFigure 6-3 on page 6-3 for an illustration of this test.

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Chapter 6. Diagnostics

STS-1

LIU

CODEC

(1 of 28)

STS-1

MAPPER

CODEC

(28 of 28)

T1/E1 LIU

(1 of 28)

T1/E1 LIU

(28 of 28)

Figure 6-3.Tributary Loopback Test

Analog Network

An ANALOG NETWORK loopback test loops the selected T1/E1 back to the network(STS-1).The T1/E1 is completelyde-multiplexed,looped back at the T1/E1 line interface unit (LIU) through the LIU drivers and receivers, and multiplexed back onto theSTS-1network stream. SeeFigure 6-4 for an illustration of this test.

STS-1

LIU

CODEC

(1 of 28)

STS-1

MAPPER

CODEC

(28 of 28)

T1/E1 LIU

(1 of 28)

T1/E1 LIU

(28 of 28)

Figure 6-4.Analog Network Loopback

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Digital Line/Net

A DIGITAL LINE/NET loopback performs a loopback of the selected T1/E1 in both the network and local loop directions. Both loopbacks occur at the T1/E1 LIU. The network side loopback occurs deep into the LIU through the receiver, receive equalizer, transmit jitter attenuator, and finally, through the T1/E1 transmit drivers. SeeFigure 6-5 for an illustration of this test.

STS-1

LIU

CODEC

(1 of 28)

STS-1

MAPPER

CODEC

(28 of 28)

T1/E1 LIU

(1 of 28)

T1/E1 LIU

(28 of 28)

Figure 6-5.Digital Line/Network Loopback

Codec Line/Net

A CODEC LINE/NET loopback performs a loopback of the selected T1/E1 in both the network and local loop directions. Both loopbacks occur at the T1/E1 codec. Both the network and the local loop side of the loopback are executed at the edge of the codec, completely testing theSTS-1mapper and the T1/E1 LIU. SeeFigure 6-6 for an illustration of this test.

STS-1

LIU

CODEC

(1 of 28)

STS-1

MAPPER

CODEC

(28 of 28)

T1/E1 LIU

(1 of 28)

T1/E1 LIU

(28 of 28)

Figure 6-6.Codec Loopback

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Chapter 6. Diagnostics

CSU Loopback

A CSU LOOPBACK enables the MX2800STS-1to generate a CSUloop-uppattern (001001…) towards the T1 CSU attached to the selected T1 line for six seconds. After six seconds have elapsed, the pattern will cease and incoming network traffic will be passed through to the CSU device. If the CSU device responded to the CSUloop-uppattern, it will return all data back towards the network. Aloop-downpattern (0000100001….) will be generated towards the CSU for six seconds whenDATA MODE is selected.

When in CSU LOOPBACK, only theDATA MODE for the T1 under test may be selected. Selecting any other option will result in an error message being displayed.

CSU Loopback w/BERT

A CSU LOOPBACK W/BERT enables the MX2800STS-1to test the local T1 loop to the CSU using the standard QRSSpseudo-randombit sequence. WhenCSU LOOPBACK W/BERT is selected, the MX2800STS-1will initiate a CSU loopback towards the CSU attached to the selected T1 line similar to theCSU LOOPBACK test above. Six seconds after starting the CSUloop-uppattern, the MX2800STS-1will cease sending the CSUloop-uppattern and begin sending an unframed 511 pattern towards the CSU. If the CSU device responded to the CSUloop-uppattern, the

MX2800 STS-1will check the incoming pattern for errors. Additional menu items will appear to show the state of pattern synchronization, error count, and a clear error count option (seeFigure 6-7 on page 6-6).SelectingDATA MODE will cease the transmission of the QRSS pattern and start transmission of a loopdown pattern as previously described.

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Only one T1 port may engage a CSU LOOPBACK,CSU LOOPBACK

W/BERT, or a LINEBERT. If a CSU LOOPBACK, CSU LOOPBACK

W/BERT, or aLINE BERT is already active at the time a newCSU

LOOPBACK, CSU LOOPBACK W/BERT, or LINEBERTis selected, the

former test will be terminated and the latter test will be engaged.

Figure 6-7.Diagnostics Menu with BERT Selected

VT BERT

A VT BERT enables the MX2800STS-1to perform a“head-to-head”BERT test towards theSTS-1network. SelectingVT BERT will replace all incoming T1/E1 traffic for the T1/E1 mapped to the selected VT with anunframed QRSS pattern towards the network. WhenVT BERT is selected, additional menu items will appear to show the state of pattern synchronization, cumulative error count, and a clear error count option. SelectingDATA MODE will cease QRSS pattern generation and substitution of the incoming data stream. SeeFigure 6-8 on page 6-7 for an illustration of this test.

When in VT BERT mode, only theDATA MODE option for the VT/Port under test may be selected. Selecting any other option will cause an error message to be displayed.

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STS-1

LIU

CODEC

(1 of 28)

STS-1

MAPPER

CODEC

(28 of 28)

T1/E1 LIU

(1 of 28)

T1/E1 LIU

(28 of 28)

Figure 6-8.VT Bert Test

Line BERT

A LINE BERT enables the MX2800STS-1to perform a“head-to-head”BERT test towards the T1/E1 line mapped to the VT selected. SelectingLINE BERT will replace all outgoing T1/E1 traffic for the T1/E1 mapped to the selected VT with anunframed QRSS pattern. WhenLINE BERT is selected, additional menu items will appear to show the state of pattern synchronization, cumulative error count, and a clear error count option. SelectingDATA MODE will cease QRSS pattern generation and substitution of the incoming data stream. SeeFigure 6-8 for an illustration of this test.

When in LINE BERT mode, only theDATA MODE option for the VT/Port under test may be selected. Selecting any other option will result in an error message being displayed.

STS-1

STS-1

MAPPER

LIU

 

CODEC

T1/E1 LIU

(1 of 28)

(1 of 28)

CODEC

 

T1/E1 LIU

(28 of 28)

 

(28 of 28)

 

 

 

Figure 6-9.Line Bert Test

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