1 00:00:00,792 --> 00:00:02,338 In this lesson, 2 00:00:02,338 --> 00:00:03,180 we're going to discuss the various fiber cable issues 3 00:00:03,180 --> 00:00:05,910 you may experience, such as incorrect transceivers, 4 00:00:05,910 --> 00:00:09,300 transmit receiver being reversed or dirty optical cables. 5 00:00:09,300 --> 00:00:11,220 Now, first we might experience issues 6 00:00:11,220 --> 00:00:12,960 with incorrect transceivers. 7 00:00:12,960 --> 00:00:14,550 A transceiver is a transmitter 8 00:00:14,550 --> 00:00:16,860 and a receiver in a single device. 9 00:00:16,860 --> 00:00:18,000 Transceivers are going to be used 10 00:00:18,000 --> 00:00:20,580 to convert a network connection from one type to another, 11 00:00:20,580 --> 00:00:23,340 and they work at layer one of the OSI model. 12 00:00:23,340 --> 00:00:25,403 In your routers and switches, 13 00:00:25,403 --> 00:00:27,390 it's common to use a transceiver for your fiber connections, 14 00:00:27,390 --> 00:00:29,730 but if you're going to be using the wrong transceiver, 15 00:00:29,730 --> 00:00:31,980 this connection simply won't work. 16 00:00:31,980 --> 00:00:34,530 Many transceivers are considered hot-pluggable, 17 00:00:34,530 --> 00:00:37,588 and they can be taken out and replaced without shutting down 18 00:00:37,588 --> 00:00:39,900 the associated router, switch or SAN device. 19 00:00:39,900 --> 00:00:42,270 If a transceiver fails and you need to replace it, 20 00:00:42,270 --> 00:00:43,650 this becomes quite easy 21 00:00:43,650 --> 00:00:45,900 since you can simply unplug the bad transceiver 22 00:00:45,900 --> 00:00:47,550 and plug in your replacement, 23 00:00:47,550 --> 00:00:50,340 but you need to ensure you're using the correct transceiver. 24 00:00:50,340 --> 00:00:52,200 Otherwise, you're going to have problems. 25 00:00:52,200 --> 00:00:54,840 If you put in the wrong type of SFP transceiver, 26 00:00:54,840 --> 00:00:56,070 you're going to have data loss 27 00:00:56,070 --> 00:00:58,320 and a loss of connectivity over time. 28 00:00:58,320 --> 00:01:00,120 Remember, transceivers are designed 29 00:01:00,120 --> 00:01:01,800 to support a certain type of connection 30 00:01:01,800 --> 00:01:03,450 and a certain type of cable. 31 00:01:03,450 --> 00:01:06,210 If you're using a longwave SFP transceiver, 32 00:01:06,210 --> 00:01:08,610 but then connect a shortwave fiber cable to them, 33 00:01:08,610 --> 00:01:09,723 that's not going to work. 34 00:01:10,872 --> 00:01:12,510 Therefore, if you have a device that's no longer working 35 00:01:12,510 --> 00:01:14,610 and you recently changed out your transceiver, 36 00:01:14,610 --> 00:01:16,080 you should go back and double check 37 00:01:16,080 --> 00:01:18,030 that you're using the right model for your device 38 00:01:18,030 --> 00:01:19,800 and your associated cabling. 39 00:01:19,800 --> 00:01:22,530 Next, we can sometimes have issues when our transmit 40 00:01:22,530 --> 00:01:24,690 and receive ends are being reversed. 41 00:01:24,690 --> 00:01:25,980 Now, while this may occur 42 00:01:25,980 --> 00:01:28,050 in a twisted pair network occasionally, 43 00:01:28,050 --> 00:01:29,820 this is really going to be the biggest issue 44 00:01:29,820 --> 00:01:31,950 inside your fiber-based networks. 45 00:01:31,950 --> 00:01:34,680 Remember, most of our fiber connections are going to consist 46 00:01:34,680 --> 00:01:37,800 of two individual cables, one for transmission of data, 47 00:01:37,800 --> 00:01:39,720 and one for receiving that data. 48 00:01:39,720 --> 00:01:41,460 For example, if you're connecting a switch 49 00:01:41,460 --> 00:01:43,860 to a workstation using a network interface card, 50 00:01:43,860 --> 00:01:45,660 that is ST connections on it, 51 00:01:45,660 --> 00:01:48,150 one of those is going to be labeled TX for transmit. 52 00:01:48,150 --> 00:01:50,670 The other one is going to be RX for receive. 53 00:01:50,670 --> 00:01:53,730 Now, if you connect the transmit cable to the RX connection 54 00:01:53,730 --> 00:01:55,920 and the receive cable to the TX connection, 55 00:01:55,920 --> 00:01:57,930 you're not going to get a valid link or connection 56 00:01:57,930 --> 00:01:58,763 to that switch. 57 00:01:59,908 --> 00:02:01,200 If this happens, you can quickly identify 58 00:02:01,200 --> 00:02:03,630 and fix this by simply disconnecting the TX 59 00:02:03,630 --> 00:02:06,720 and RX port cables and swapping those cables. 60 00:02:06,720 --> 00:02:08,100 Then when you do that, 61 00:02:08,100 --> 00:02:10,949 you can check the LED link activity lights on your NIC, 62 00:02:10,949 --> 00:02:12,750 and you're going to see the link is now online 63 00:02:12,750 --> 00:02:15,540 and available as indicated by a solid orange light 64 00:02:15,540 --> 00:02:17,340 or a blinking orange light if the network 65 00:02:17,340 --> 00:02:19,500 is actively communicating again. 66 00:02:19,500 --> 00:02:22,020 Finally, we have dirty optical cables. 67 00:02:22,020 --> 00:02:23,310 Dirty fiber optic cables 68 00:02:23,310 --> 00:02:25,740 and connectors can cause major performance issues 69 00:02:25,740 --> 00:02:28,110 or connection problems inside your network. 70 00:02:28,110 --> 00:02:30,510 A dirty fiber just means something is interfering 71 00:02:30,510 --> 00:02:32,910 with the clear optical connection between the cable, 72 00:02:32,910 --> 00:02:34,560 the connector, and the connection port 73 00:02:34,560 --> 00:02:36,060 for the fiber connection. 74 00:02:36,060 --> 00:02:38,130 Even something as small as some dust or dirt 75 00:02:38,130 --> 00:02:40,860 or your fingerprints can really severely block the light 76 00:02:40,860 --> 00:02:42,630 being sent down that cable. 77 00:02:42,630 --> 00:02:45,810 Now remember, multimode fibers are only 50 78 00:02:45,810 --> 00:02:47,880 to 62 microns in diameter, 79 00:02:47,880 --> 00:02:50,880 so it really doesn't take much to block these connections. 80 00:02:50,880 --> 00:02:53,070 If you find yourself with a dirty optical cable 81 00:02:53,070 --> 00:02:55,110 or connector, you really just need to clean it 82 00:02:55,110 --> 00:02:57,900 using a dry cleaning or wet cleaning method. 83 00:02:57,900 --> 00:03:00,240 Dry cleaning involves simply using light pressure 84 00:03:00,240 --> 00:03:03,240 while rubbing the end face of a fiber cable or connector 85 00:03:03,240 --> 00:03:06,180 using a dry cleaning cloth in one direction. 86 00:03:06,180 --> 00:03:08,310 This will usually be used when you need to clean dust 87 00:03:08,310 --> 00:03:10,350 or dirt off the face of a connector. 88 00:03:10,350 --> 00:03:11,940 This same technique can be used 89 00:03:11,940 --> 00:03:13,950 for a fiber connection port on a switch 90 00:03:13,950 --> 00:03:15,990 or network interface card too. 91 00:03:15,990 --> 00:03:18,150 Wet cleaning involves lightly moistening a piece 92 00:03:18,150 --> 00:03:21,150 of lint-free cloth with a fiber optic cleaning solution, 93 00:03:21,150 --> 00:03:22,830 and then wiping the end face of the cable 94 00:03:22,830 --> 00:03:24,720 in one direction as well. 95 00:03:24,720 --> 00:03:27,480 This cleaning solution should be 91% or higher 96 00:03:27,480 --> 00:03:30,720 isopropanol alcohol if you're using a solution. 97 00:03:30,720 --> 00:03:33,000 Now, wet cleaning is considered more invasive 98 00:03:33,000 --> 00:03:35,070 than dry cleaning, but it is useful 99 00:03:35,070 --> 00:03:37,470 when trying to remove oil residues or films 100 00:03:37,470 --> 00:03:39,210 off those cables and connectors, 101 00:03:39,210 --> 00:03:41,670 such as if somebody has put their fingerprints on them. 102 00:03:41,670 --> 00:03:42,840 You're going to have to use wet clean 103 00:03:42,840 --> 00:03:44,550 to get those fingerprints off. 104 00:03:44,550 --> 00:03:46,560 Now, if you start receiving a large amount 105 00:03:46,560 --> 00:03:48,300 of errors over a fiber connection 106 00:03:48,300 --> 00:03:50,220 or your performance begins to slow down, 107 00:03:50,220 --> 00:03:51,570 it could be the indication 108 00:03:51,570 --> 00:03:53,820 that you need to clean a dirty fiber. 109 00:03:53,820 --> 00:03:55,710 This can also be quantitatively determined 110 00:03:55,710 --> 00:03:57,540 if you're using a fiber light meter 111 00:03:57,540 --> 00:03:59,280 because you can compare the decibel reading 112 00:03:59,280 --> 00:04:02,583 from your baseline of a clean fiber versus this dirty fiber.