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Remote Powered and IMA (T1) Fed DSLAM Site Maintenance

Presented by Vernon May

Columnist for ISE Magazine

©Vernon May Solutions LLC 2018 All rights reserved. Proprietary and Confidential Information

Normal DSLAM Configuration• Uses Commercial Power

• DSLAM Data Feed is Fiber Optic

Advantages

• Reliable power source

• High Capacity Data Feed

Disadvantages

• Cost

©Vernon May Solutions LLC 2017- All rights reserved. Proprietary and Confidential Information

3

T1 Fed DSLAM Configuration• Uses Commercial Power

• DSLAM Data Feed is multiple T1’s

Advantages

• Reliable Power Source

• Uses Existing Copper

Disadvantages

• Very Low Capacity Data Feed

• Dangerous Voltage


4

Remote Powered DSLAM Configuration• Uses Cable Pairs to Power Site

• DSLAM Data Feed is Fiber Optic

Advantages

• Uses Existing Copper

• High Capacity Data Feed

Disadvantages

• Questionable Power Source

• Dangerous Voltage


5

The Copper Link

• T1 Circuits are very susceptible to resistance faults

• T1 Circuits are very susceptible to cross battery faults

• T1 Voltages can be dangerous to technicians

• Remote Power Circuits are very susceptible to resistance faults

• Remote Power Circuits are very susceptible to cross battery faults

• Remote Power Voltages can be very dangerous to technicians


6

R

RR R

R

R

R

Voice and Data Network Transport

5 Voice and 8 Data T1’s with 7 Repeaters

OPM and DSLAM

Study Site

Symptoms:• No Comm to

DSLAM • Internet is

completely down

• Repeater power comes from CO

• Repeaters are 6KFT apart

Cabinet Extension



completely down

Cabinet ExtensionT1 Equipment (Side)



completely down

Cabinet ExtensionT1 Equipment



completely down

Initial Trouble Shooting

• Commercial Power was on and no breakers were engaged

• DSLAM was powered and would communicate through the local port

• All 8 T1’s were down

• Recent digging in the area of the cable path proved to be 6 feet from the cable path

• All 8 T1’s remotely reset• 4 Circuits came up with no errors• 1 Circuit was up with errors• 3 Circuits were still down

• DSLAM regained Comm and Internet came up


11

Repeater #3 Symptoms:

• Internet is slow

• 3 T1’s Down• 1 T1 taking

errors• Testing

causes working T1’s to drop and come back

Repeater #3 Splice Symptoms:



errors• Testing


Repeater #3 Splice Symptoms:



errors• Testing


Repeater #3 Shelf Symptoms:



errors• Testing


Repeater #3Repeater Slot Converter Symptoms:



errors• Testing


4 Bad Circuits

• Circuit A: Up, but taking errors

• Circuit B: Completely Down

• Circuit C: Completely Down

• Circuit D: Completely Down


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Repeater #3 Loopback

Repeater #4 Loopback

• Circuit A: Up, No Errors• Circuit B: Down• Circuit C: Up, No Errors• Circuit D: Up, No Errors

• Circuit A: Down• Circuit B: Down• Circuit C: Up, with Errors• Circuit D: Down

Copper Testing Between Repeaters 3

and 4• Circuit A: Short, Ground and Cross• Circuit B: Short, Ground and Cross• Circuit C: Short, Ground, Cross and

High Open• Circuit D: Short, Ground and Cross


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Pedestal

Flooded Creek

Splice In Pedestal Between R3 and R4

• Air trapped in the pedfloated the ped to the top of the water

• The bonding in the pedheld the cables, so they were pulled out of the ground

• Ped Cap splice was full of water

• All circuits wet in splice

After Fix• Circuit A: Up, No Errors• Circuit B: Down• Circuit C: Up, No Errors• Circuit D: Up, No Errors• Testing no longer

impacts other circuits

What about Circuit B?

Circuit B:• Near 0 Ohm

Ground at R3

• Defective carbon surge protector found and replaced

• All 8 Circuits up and No Errors

Conclusions

• Wet Splice impacted all circuits in some way

• Wet Splice caused errors on Circuit A

• Wet Splice killed Circuits C and D

• Wet Splice caused testing to kill the 4 “working circuits”

• Defective Carbon grounded out Circuit B


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Why is water so bad?• Electrolysis breaks down

the copper in all the cable pairs

Why is water so very bad for T1 and Remote Power Circuits?• The more voltage, the

more damage and faster

High Voltage Copper Circuit Symptoms Lists

T1 Fed DSLAM

• Bi-polar Violations

• Circuits going up and down

• Activity on one circuit impacts others

• Random DSL Ports dropping

• Subscribers losing authentication

• Slower DS Bit Rates per Circuit

• Slower Site Bit Rates


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Remote Power

What is a good cable pair for high voltage circuits?

Passing

• Short > 10 Mohms

• Ground > 20 Mohms

• Battery < 1 VDC

• Cap Balance > 98%

• Longitudinal Balance > 85 dB

• Circuit Voltage Reduced

• Reduced Voltage and Cap Balance

• Electrolysis and all pairs damaged

• Full or Series Open

• Some physical issue exists


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Failure Impact

Recommended Alarms

T1 Fed DSLAM

• DSL Circuit throughput issues

• Site throughput issues

• T1 Circuit Errors

• T1 Circuit Up/Down

• DSLAM Comm is down

• DSL Circuit throughput issues

• Site throughput issues

• Low Site Voltage

• Low Input Voltage (Per Pair)

• DSLAM Comm is down


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Remote Power

Thank YouPlease see our booth at Space 1038

Please read the Network Maintenance Corner in ISE Magazine


27

Documents

DSL Operations and Problem Solving - ISE EXPO...on any registration confirmations) to view/print their seminar certificates. If a certificate is needed on-site, the attendee may visit