What you will learn on this page

Starting at the bottom. The hardware layer. Connectors, cables, patching, and cable management systems.

Key Changes and Emphases in the OSI Stack

Cable Types

Cat 5e should be used instead. Cat5e Uses 4 pairs of unshielded twisted pair. Good for 1 Gbps (1000BASE-T) over 100 meters, with a bandwidth of 100 MHz (enhanced for reduced crosstalk). It's the minimum standard for Gigabit Ethernet. The "e" in Cat 5e stands for enhanced. This cable is capable of handling disturbances on all pairs caused by transmitting on all 4 pairs simultaneously. Cat 5e was generally the same price as Cat 5, but now has been phased out.

Cat6 Uses 4 pairs of unshielded twisted pair. Good for data rates up to 1 Gbps (250 MHz). Length limit = 328 ft. It can support 10 Gbps over shorter distances (up to 55m) It should at least be used for "riser" cables (between floors). Obviously not of much use within a truck but might be necessary for a compound. It should be kept in mind that “yanking” on cable can change the cable’s bandwidth or throughput because of changes to the twist and spacing of the various pairs in the cable.

Typical punch down block and the tool required to insert wires into the block

Cable Termination

Often, for maximum flexibility, you don’t run cables straight from one node to the next, but to what is known as punch down blocks; the solid copper wires are "punched down" into short open-ended slots.

The most common type of block is known as a 110 block. 110 blocks are typically for terminating wires (e.g., in telco or data closets). These blocks are sized to handle from 25 to over 500 pairs. It can pass 1 Gbps traffic using Cat 6 cable, but Cat 6 cable is difficult to work with due to its size.

Speed/Bandwidth

Originally a single coax cable was used to connect all nodes on a segment together, and the cable was actually tapped, outer shield and inner conductor “bit into”, so an AUI (Attachment Unit Interface) could be added that actually connected to the node.

Original Ethernet connectivity

Faster 10/100BaseT devices followed (10 and 100 Mbps speed) that no longer used coax but rather Cat 3, 4, or 5 cable. Devices or nodes today sense what bandwidths are available from other nodes and what the cable path will support; they can automatically sense the speed of the node it is connected to and will connect accordingly. Today many paths, especially if handling video data, are 1000 Mbps or 1 Gbps.

In 2110, 10 GbE is typically carrying high, constant-rate RTP streams (often multiple flows per endpoint). That makes link quality and error performance more critical than in bursty IT traffic. Cat5e: not a reliable 10GBASE-T medium (generally not acceptable for 10G planning). Cat6 can work for 10GBASE-T, but it is distance-limited: Typical guidance: ~55 m (180 ft) in many real-world installations (depends heavily on alien crosstalk environment, bundling, and terminations).

Some terminalogy here: such as 10GBASE-T 10G: First part indicates speed.The speed (10 Gigabits).
The second part BASE: indicates "Baseband" signaling, meaning the medium carries only one signal at a time.
Next -T: "Twisted-pair," referring to the standard copper Ethernet cables you likely use at home or in the office (like Cat6a).

Sometimes PHY follows (10GBASE-T 10G PHY).
What is a PHY? PHY is short for the Physical Layer. It is the actual electronic chip (transceiver) inside a network card or switch that translates digital data from your computer into the electrical signals sent over the wire.

Today the way signals are inserted and recovered from this layer are significantly more complex than older versions. The Drivers/receivers at each end of the path now use Digital Signal Processing (DSP) to perform massive amounts of "math" in real-time to keep the signal clean over a copper wire. It constantly cancels out "echoes" and electrical noise (crosstalk) from the other wires inside the cable. It uses a modulation technique called PAM-16 to pack more data into each electrical pulse. Because of all this processing, 10GBASE-T PHYs consume more power (typically 2.5W to 5W per port) and generate more heat than fiber-optic or lower-speed copper equivalents. It also adds a bit more latency (approx. 2.5 to 3 microseconds).

Many modern 10GBASE-T PHYs include a "Short-Reach" or "Low Power" mode. The PHY automatically detects if the cable is short and scales down its processing to save energy and reduce heat. The distance is typically limited to under 30 meters. Benefit: Power consumption can drop from ~5W per port to ~2.5W, which is critical for SFP+ transceivers that have strict thermal limits.

What are SFP (Small Form-factor Pluggable) transceivers? Think of an SFP port as a "universal socket." Instead of buying a switch with permanent fiber or copper ports, you buy one with empty SFP slots and plug in the specific transceiver needed for your cable type and distance. SFP is a 1G capable unit, while SFP+ is 10G capable, and it is considered a 2110 edge capable adapter.. There is also a SFP28 designation. It handles 25G.It is considered a high density edge connection.

Now there are QSFP+ adaptors (Quad Small Form-factor Pluggable Plus) which handle 40G aggregation duties. Finally, for now, there is the QSFP28 adaptor which handles up to 100G.

To recap, SFP+/SFP28 are common at endpoints (cameras, multiviewers, gateways). QSFP+/QSFP28 are common in the switch fabric (leaf/spine). Breakout cables allow you turn one high-capacity port into multiple 10G/25G ports, which is how dense 2110 networks stay cost-effective.

Direct Attach Copper(DAC) cable

QSFP to SFP breakout cable cable
We will cover connections, and interfacing in greater detail in the NIC section.

Instead of cables connecting to a SFP via RJ-45s a Direct Attach Copper (DAC) adapter could be used. Direct Attach Copper (DAC) is a high-speed, factory-terminated cable assembly that connects networking devices (like switches, routers, and servers) directly, typically within the same equipment rack. Instead of using separate fiber-optic cables and transceivers, a DAC cable integrates the "transceiver" connectors directly onto both ends of a shielded twinaxial (Twinax) copper cable. This creates a "plug-and-play" solution that is significantly cheaper and more energy-efficient than fiber. Generally latency, power consumption, and the costs are lower.

Fiber

Fiber is now a common physical path. Fiber is divided into single mode and multimode. Contrary to what you would think, single mode is better, and can carry coherent information longer than multimode fiber. Single mode has a glass optic path that is narrow enough that light is directed down that path without reflecting off the outside surface of the glass stand. Multimode means that light is repeatedly reflecting off the sides at various rates. The more reflections a beam of light undergoes mean a longer total path than light that sticks to the center of the glass. Some wavelengths and light rays encounter more reflections than others. This means that over long distances, packets of light can become compressed together, making it impossible to discern the data patterns that the light represents.

Fiber Modes

• Multimode fiber has a maximum distance of up to 3000 feet. This is actually an oversimplication, and a bit inaccurate; Distances vary by fiber type (e.g., OM1: 275m for 1 Gbps; OM4: 400m for 10 Gbps) and speed. It's not a fixed 3000 feet across all scenarios.
• Single Mode Fiber has a maximum distance of up to 25 miles (40Km).
 Glass has greater distance, but copper is less expensive. Again, the distance statment is a bit of a oversimplication. It can exceed 100 km with proper amplification, depending on wavelength (e.g., 1310nm or 1550nm) and the equipment used.

SMPTE 304M connector is a hybrid connector that includes both fiber, power, and low voltage control signal all in one

Hybrid Fiber Coaxial (HFC) is a telecommunications industry term for a network that incorporates both optical fiber and coaxial cable to create a bandwidth network. called 10baseT, which was half duplex. This meant only one node at either end of the line could send at once, the other had to listen. This made available bandwidth use only 30 to 40% efficient, which meant that only 3 to 4 Mbps could be passed back and forth per second. Half duplex is not common today.

Historically a large chunk of what people in the field dealt with daily was camera cable. IT has evolved greatly over the last 15 years.

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Fiber also has four common connector types:

• ST (Straight Tip) Connector—Developed by AT&T, this uses a BNC attachment mechanism which is popular, but mainly for multimode fiber. Early LANs (10Base-F), fiber patch panels. Easy to insert and remove, low cost. Disadvantage: Exposed ferrule Ferrules are any sort of ring used to either reinforce a shaft or bind together strands of a material. In the context of wiring, a ferrule is a small deformable metal tube, generally made out of tin plated copper. This short tube (or long ring) is placed over a section of stranded wire extending from stripped insulation, then compressed with a crimping tool to hold the strands together. Ferrules discussed here also feature a flared portion on one end, which serves to guide the strands into the main crimped section and provide strain relief. makes it more fragile and prone to dust.

• SC (Subscriber or Square) Connector—Connectors are push-pull latch mechanism, so this works for either SMF or MMF. Good mechanical stability, inexpensive. Good for 1000 matings. Common in switches, routers, and GBIC transceivers. Disadvantages: Can disconnect if pulled sharply, larger footprint compared to LC.

• FC Fiber Connector (Ferrule Connector)
Round, metal body with screw-threaded connection. Applications: Telecom systems, ODF frames, long-haul networks. Rugged, dust-resistant, highly reliable under vibration. Disadvantages: Slower to install due to threaded coupling.

Another type:
• LC (Local Connector)—Small form factor, RJ-style latch. Popular for Fibre-Channel and Gigabit Ethernet adapters. This connector is replacing SC connectors because of its smaller form factor.Dominant in SFP/SFP+ modules, modern data centers, high-density panels. Compact size, high port density, reliable performance. Disadvantages: Smaller size makes it harder to handle without tools.

Many connectors are Angle-Polished Connectors (APC). These are generally distinguished by some green on the connector. They have the fiber end face polished at an angle that prevents light reflecting back from its surface of the fiber strand it is facing to reverse back down the fiber strand it just traveled. This is known as insertion loss. Any optical reflections can reduce the distance that the light can travel.

Fiber Connector Polishing Types: PC, UPC, and APC

The end-face geometry of a connector ferrule greatly affects return loss.


• PC (Physical Contact): Flat or slightly curved surface. Standard in many networks.
• UPC (Ultra Physical Contact): Improved polish with tighter tolerances, lower insertion and return loss.
• APC (Angled Physical Contact): 8° angled end-face; minimizes back reflection, critical in analog and RF-over-fiber systems like CATV