Networking Concepts · Topic 6 of 11
Transmission Media and Transceivers
Compare copper categories, fiber types, coax, connectors, SFP transceivers, termination standards, wireless and satellite media for the Network+ exam.
- 5 min
- Twisted pair segments are limited to 100 meters.
- Cat 5e supports 1 Gbps, Cat 6a supports 10 Gbps to 100 meters, and Cat 6 supports 10 Gbps only up to about 55 meters.
- Single mode fiber goes farther than multimode and uses a laser.
What it is
Transmission media is whatever carries the signal: copper cable, fiber optic cable, radio or satellite. Transceivers are the small modules that turn the switch's electrical signal into the signal for the chosen medium.
The exam asks you to match media, connectors and standards to a distance and speed requirement. It also tests the cable ratings and termination standards used in an installation.
How it works
Copper twisted pair
Twisted pair cable has four pairs of wires. Higher categories reduce interference and support more speed.
| Category | Typical maximum speed | Notes |
|---|---|---|
| Cat 5 | 100 Mbps | Old, rarely installed now |
| Cat 5e | 1 Gbps | Enhanced crosstalk performance |
| Cat 6 | 1 Gbps, and 10 Gbps over short runs | Short run limit is about 55 meters |
| Cat 6a | 10 Gbps to 100 meters | Augmented, built for full length 10 Gbps runs |
| Cat 7 | 10 Gbps | Fully shielded design |
| Cat 8 | 25 or 40 Gbps | Short runs only, aimed at data centers |
Standard copper Ethernet limits a segment to 100 meters. Unshielded twisted pair (UTP) is common, and shielded twisted pair (STP) adds protection from electromagnetic interference (EMI).
The Ethernet names follow a pattern. For example, 1000BASE-T means 1 Gbps over twisted pair, and 10GBASE-T means 10 Gbps over twisted pair.
Cable jacket ratings
Plenum cable has a fire retardant jacket that produces little smoke. It is required in air handling spaces such as ceilings used for airflow. Polyvinyl chloride (PVC) cable is cheaper and used in other areas.
Coaxial and twinaxial
Coaxial cable has a center conductor with shielding around it. RG-6 and RG-59 are common types, used for cable television and broadband, and they connect with F-type connectors. Twinaxial cable is a short, cheap copper link used inside a rack or between nearby devices.
A Bayonet Neill-Concelman (BNC) connector is a coax connector that locks with a quarter turn twist. It was used for 10BASE2 thin coax Ethernet and is still common on video and security camera cabling.
Fiber optic
Fiber carries light and is not affected by EMI. Single mode fiber has a very thin core and a laser, and it reaches long distances. Multimode fiber has a wider core, uses cheaper light sources and is meant for shorter runs such as inside a building or campus.
| Connector | Description |
|---|---|
| LC (Lucent Connector) | Small form factor, common on switches and SFPs |
| SC (Subscriber Connector) | Square push pull connector |
| ST (Straight Tip) | Round bayonet style connector, older |
| MPO (Multi fiber Push On) | One connector with many fibers, used for high speed links |
| RJ-45 | Eight pin copper Ethernet connector |
| RJ-11 | Smaller telephone connector |
| F-type | Threaded coax connector |
Transceivers
| Form factor | Typical speed |
|---|---|
| Small Form factor Pluggable (SFP) | 1 Gbps |
| SFP+ | 10 Gbps |
| Quad SFP (QSFP) and QSFP+ | 40 Gbps, built from four lanes |
Fiber standards use letters for reach: SX and SR mean short reach over multimode, while LX and LR mean long reach, normally over single mode (for example 1000BASE-SX and 10GBASE-LR). A media converter joins two media, for example copper Ethernet to fiber.
Transceivers must match the fiber type and the module at the other end. Bidirectional (BiDi) modules send and receive on two wavelengths over a single fiber strand. Wavelength division multiplexing (WDM) carries several wavelengths over one fiber to increase capacity.
Fibre Channel (FC) is a separate protocol from Ethernet, used mainly for storage area networks (SANs) that link servers to storage. FC modules use the same SFP style form factor and come in speeds such as 8, 16 and 32 Gbps. An FC module does not work in an Ethernet port, and an Ethernet module does not work in an FC port.
Termination
Wires in an RJ-45 jack and plug follow either the TIA/EIA-568A or TIA/EIA-568B color order (Telecommunications Industry Association and Electronic Industries Alliance standards). A straight through cable uses the same standard on both ends, and a crossover cable uses A on one end and B on the other.
Cable ends at a patch panel, a 110 block or a 66 block. A 110 block is used for data, and a 66 block is older and used for telephone. A fiber distribution panel terminates fiber runs.
Wireless and satellite media
Wireless media includes 802.11 Wi-Fi, cellular and satellite. Satellite reaches remote areas but adds noticeable delay because the signal travels a long distance.
What to remember for the exam
- Twisted pair segments are limited to 100 meters.
- Cat 5e supports 1 Gbps, Cat 6a supports 10 Gbps to 100 meters, and Cat 6 supports 10 Gbps only up to about 55 meters.
- Single mode fiber goes farther than multimode and uses a laser.
- Fiber is immune to EMI and is the choice for long runs and electrically noisy areas.
- Plenum cable is for air handling spaces and is fire retardant.
- SFP is 1 Gbps, SFP+ is 10 Gbps, and QSFP is 40 Gbps.
- Straight through uses the same standard at both ends. Crossover uses 568A at one end and 568B at the other.
- RG-6 and RG-59 are coax types that use F-type connectors.
When a scenario mentions a distance over 100 meters or heavy EMI, move from copper to fiber. When it says "inside the ceiling air space", think plenum.
Common mistakes
Believing Cat 6 always gives 10 Gbps. It does so only over short distances. Use Cat 6a for a full 100 meter run at 10 Gbps.
Mixing fiber types. A single mode transceiver does not work correctly with multimode fiber, so the module and the cable must match.
Using non plenum cable in an air handling space. Safety codes call for plenum rated jackets there.
Confusing connector names. LC is small, SC is square, and ST is round with a twist lock.
Confusing the 110 block and the 66 block. The 110 block is the modern data termination, and the 66 block is the older voice one.
Copper has a 100 meter limit for each segment. If the run is longer, the answer is a repeater or switch in between, or fiber, not a higher Cat number.
Check yourself
Try these three.
Which fiber type suits a 20 kilometer link?
Single mode fiber, which uses a laser and reaches long distances.
What is the maximum length of a twisted pair Ethernet segment?
100 meters.
Which module form factor normally carries 10 Gbps?
SFP+.
Topic 6 of 11 in Networking Concepts
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