-: Fiber cable issues. 2 2
In this lesson, we're going to discuss 3 3
the various fiber cable issues you may experience 4 4
such as incorrect transceivers, 5 5
transmit and receive being reversed, 6 6
or dirty optical cables. 7 7
Now, first, we might experience issues 8 8
with incorrect transceivers. 9 9
A transceiver is a transmitter and receiver 10 10
in a single device. 11 11
Transceivers are going to be used 12 12
to convert a network connection from one type to another, 13 13
and they work at layer one of the OSI model. 14 14
In your routers and switches, 15 15
it's common to use a transceiver for your fiber connections, 16 16
but if you're going to be using the wrong transceiver, 17 17
this connection simply won't work. 18 18
Many transceivers are considered hot pluggable, 19 19
and they can be taken out, replaced 20 20
without shutting down the associate router, 21 21
switch or SAN device. 22 22
If a transceiver fails and you need to replace it, 23 23
this becomes quite easy 24 24
since you can simply unplug the bad transceiver 25 25
and plug in your replacement. 26 26
But you need to ensure 27 27
you're using the correct transceiver, 28 28
otherwise, you're going to have problems. 29 29
If you put in the wrong type of SFP transceiver, 30 30
you're going to have data loss 31 31
and a loss of connectivity over time. 32 32
Remember, transceivers are designed 33 33
to support a certain type of connection 34 34
and a certain type of cable. 35 35
If you're using a long wave SFP transceiver, 36 36
but then connect a short wave fiber cable to them, 37 37
that's not going to work. 38 38
Therefore, if you have a device that's no longer working 39 39
and you recently changed out your transceiver, 40 40
you should go back and double-check 41 41
that you're using the right model for your device 42 42
and your associate cabling. 43 43
Next, we can sometimes have issues 44 44
when our transmit and receive ends are being reversed. 45 45
Now, while this may occur 46 46
in a twisted pair network occasionally, 47 47
this is really going to be the biggest issue 48 48
inside your fiber-based networks. 49 49
Remember, most of our fiber connections 50 50
are going to consist of two individual cables, 51 51
one for transmission of data 52 52
and one for receiving that data. 53 53
For example, if you're connecting a switch 54 54
to a workstation using a network interface card 55 55
that has ST connections on it, 56 56
one of those is going to be labeled TX for transmit. 57 57
The other one is going to be RX for receive. 58 58
Now, if you connect the transmit cable 59 59
to the RX connection, 60 60
and the receive cable to the TX connection, 61 61
you're not going to get a valid link 62 62
or connection to that switch. 63 63
If this happens, you can quickly identify and fix this 64 64
by simply disconnecting the TX and RX port cables 65 65
and swapping those cables. 66 66
Then, when you do that, 67 67
you can check the LED link activity lights on your NIC, 68 68
and you're going to see the link is now online and available 69 69
as indicated by a solid orange light 70 70
or a blinking orange light 71 71
if the network is actively communicating again. 72 72
Finally, we have dirty optical cables. 73 73
Dirty fiber optic cables and connectors 74 74
can cause major performance issues 75 75
or connection problems inside your network. 76 76
A dirty fiber just means something is interfering 77 77
with the clear optical connection between the cable, 78 78
the connector, and the connection port 79 79
for the fiber connection. 80 80
Even something as small as some dust, 81 81
or dirt, or your fingerprints 82 82
can really severely block the light 83 83
being sent down that cable. 84 84
Now, remember, multi-mode fibers 85 85
are only 50 to 62 microns in diameter, 86 86
so it really doesn't take much 87 87
to block these connections. 88 88
If you find yourself with a dirty optical cable 89 89
or connector, 90 90
you really just need to clean it 91 91
using a dry cleaning or wet cleaning method. 92 92
Dry cleaning involves simply using light pressure 93 93
while rubbing the end face of a fiber cable 94 94
or connector using a dry cleaning cloth 95 95
in one direction. 96 96
This will usually be used when you need to clean dust 97 97
or dirt off the face of a connector. 98 98
This same technique can be used for a fiber connection port 99 99
on a switch or network interface card too. 100 100
Wet cleaning involves lightly moistening 101 101
a piece of lint-free cloth 102 102
with a fiber optic cleaning solution, 103 103
and then wiping the end face of the cable 104 104
in one direction as well. 105 105
This cleaning solution 106 106
should be 91% or higher isopropanol alcohol 107 107
if you're using a solution. 108 108
Now, wet cleaning is considered more invasive 109 109
than dry cleaning, 110 110
but it is useful when trying to remove oil residues 111 111
or films off those cables and connectors, 112 112
such as if somebody has put their fingerprints on them. 113 113
You're going to have to use wet cleaning 114 114
to get those fingerprints off. 115 115
Now, if you start receiving a large amount of errors 116 116
over a fiber connection, 117 117
or your performance begins to slow down, 118 118
it could be the indication 119 119
that you need to clean a dirty fiber. 120 120
This can also be quantitatively determined 121 121
if you're using a fiber light meter, 122 122
because you can compare the decibel reading 123 123
from your baseline of a clean fiber 124 124
versus this dirty fiber. 125 125
(upbeat music)