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Finish Phase Overview • • • • Testing Troubleshooting Certification Documentation © 2002, Cisco Systems, Inc. All rights reserved. 1 Finish Phase • Steps • Testing • Troubleshooting • Certification • Documentation • Testing • Testing verifies that all wires are working so that the customer does not find that there are problems later • Testing is for functionality, that is, it determines if the wire can carry the signal from end to end © 2002, Cisco Systems, Inc. All rights reserved. 2 Finish Phase • Common Test Errors Phases of testing • Wire-mapping errors – Wires in a multi-pair cable do not terminate at the appropriate contacts in the connector at the far end • Opens – Wires in cables fail to make a continuous path from end to end. This is usually due to improper termination or breakage. Occasionally it is due to faulty cable • Shorts – Wires in cables touch each other, thus shorting the circuit • Split pairs – Wires are mixed among pairs © 2002, Cisco Systems, Inc. All rights reserved. 3 Finish Phase - Common Test Errors © 2002, Cisco Systems, Inc. All rights reserved. 4 Finish Phase • Common Testers • • • • • tone generators cable and jack testers telephone test sets multimeters TDR and OTDR • Two methods of testing • Channel Test • Link Test • Channel Test • The channel test goes truly end-to-end from the workstation or telephone to the device in the TR • The channel test includes the line cord from the jack to the user equipment © 2002, Cisco Systems, Inc. All rights reserved. 5 Finish Phase • Channel Test • Goes from workstation/phone to the TR device • The channel test includes the patch cord from the patch panel to the communications equipment • Officially eliminated by TIA/EIA-568-B.1 • Link Test • Tests cable from the wall back to the patch panel • There are two types: basic and permanent • Only permanent link test is acceptable per TIA/EIA568-B.1 • Permanent Link Test • Excludes the cable portions of the adapters, but includes the mated connection at each end © 2002, Cisco Systems, Inc. All rights reserved. 6 Finish Phase • Permanent Link Test • Allows for a consolidation point, which is desirable for open office cabling installations and is therefore more practical • The problems that should be tested for are foreign voltage, shorts, reversals, split pairs, and crosstalk • Testing for Foreign Voltage • A voltage that does not belong on the wire • Sources of foreign voltage can be dangerous • Cross-connects, insulation failures, static electricity • Inductive currents formed by routing signal wires too close to wires carrying large voltages • Multimeters can test for foreign voltage. © 2002, Cisco Systems, Inc. All rights reserved. 7 Finish Phase • Testing for Shorts • A short is formed when the two wires in a pair touch each other • Tests to determine if there is a short measure the continuity or resistance between the wires • Make these measurements with an ohmmeter using a low-resistance scale • Testing for Reversals • A cable tester is needed to determine reversals • A reversal occurs when the tip (or ring) side of a pair is terminated on the ring (or tip) position at the opposite end of the wire © 2002, Cisco Systems, Inc. All rights reserved. 8 Finish Phase • Testing for Split Pairs • Split pairs happen when wires are mixed • Test for splits with an ohmmeter & tone generator © 2002, Cisco Systems, Inc. All rights reserved. 9 Finish Phase • Testing for Crosstalk • Crosstalk occurs when the signal from a transmitting pair is coupled to the receiving pair or other pairs in the cable • Cable testers are used to detect crosstalk © 2002, Cisco Systems, Inc. All rights reserved. 10 Finish Phase • Fiber-optic Testing • Fiber-optic cables are tested using a calibrated light source and an optical power meter to measure the loss in the cable being tested © 2002, Cisco Systems, Inc. All rights reserved. 11 Finish Phase • Testing Grounding Systems • Grounding systems tests are generally performed using a special purpose instrument - a megger • Megger checks performance of grounding and bonding • The NEC states that if the grounding systems resistance to ground is 25 ohms or greater • The installer has to add a second ground rod • Reading of 5 ohms or less is considered commercially acceptable • Troubleshooting Copper Connections • Hard faults • Problems that make communication virtually impossible • Are relatively easy to identify and clear • Opens, split pairs, and shorts are examples of hard faults © 2002, Cisco Systems, Inc. All rights reserved. 12 Finish Phase • Troubleshooting Copper Connections • Intermittent faults • Come and go and cause problems such as: • Dropped packets • Packets with errors • Often, these problems are caused by crosstalk • Troubleshooting Fiber-optics • Most problems are found with the connectors • Fiber connector end faces can become scratched: • With repeated connecting and disconnecting •Dirt and dust on the end faces of the connectors can also add attenuation that will impede a fiberoptic signal © 2002, Cisco Systems, Inc. All rights reserved. 13 Finish Phase • Certification • The certification process forms a baseline measurement for the cabling system • It allows the installer to say unequivocally that at a certain day and time the cables performed • Any later change in cable performance must be attributable to some cause • it will be easier to troubleshoot • Minimum Test Results • To pass, cables must meet the minimum grade test results • The difference between the actual test results and the minimum test results is known as headroom. • If the results show lots of headroom • There should be less cable maintenance needed in the future • More tolerant of poor grade patch cords and equipment cables © 2002, Cisco Systems, Inc. All rights reserved. 14 Finish Phase • Certification • Testing is for functionality, that is, it determines if the wire can carry the signal from end to end. Certification, or performance testing, is a statement about cable performance • Performance test systems usually use a receiver on the far end that communicates over the wire to the main test unit. • Category 5e cable is tested at 100 MHz and Category 6 at 250 MHz. • Performance testing per TIA/EIA-568-B © 2002, Cisco Systems, Inc. All rights reserved. 15 Finish Phase - Certification Testing © 2002, Cisco Systems, Inc. All rights reserved. 16 Finish Phase • Common Test Specifications • Specified Frequency Range • Attenuation • Near End Crosstalk (NEXT) • Return Loss • Propagation Delay • Delay Skew • Documentation • After the cabling has been tested and certified, documentation is created • These are called as-built documents • As-builts show the client and future technicians exactly the layout of the cable installation. © 2002, Cisco Systems, Inc. All rights reserved. 17 Finish Phase • Documentation •These are called as-built documents • It may vary from the original plans since obstacles or problems may have occurred during installation • Diagrams showing the cable runs, locations of outlets, and identity of each outlet should be created and presented to the client © 2002, Cisco Systems, Inc. All rights reserved. 18