Cable Types and Length
Cables are the physical medium that transmit optical and electrical signals. Juniper offers a broad variety of high-performance and cost-effective cables. These optical and electrical cables are available in various dimensions, distance ranges, and speeds. Cables offer a wide selection of breakout configurations that enable you to operate at lower Ethernet speeds. It helps to effectively interconnect devices and increase port density. For more information, see Optical and Electrical Cables.
The two broad types of cables are:
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Direct attach copper cables (DAC)
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Active optical cables (AOC)
Direct Attach Copper Cables (DAC)
Made of Twinax copper, the primary type of DAC cable is known as Twinax Cable. It is ideal for ultra short-range connections. DAC supports high-speed connections between servers, switches, and storage devices. DAC cables are lower cost. It is more durable than optical fibers. Also, it is less susceptible to dust and environmental disturbances.
DAC cables can be of two types:
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Passive DAC cables—Passive DAC cables transmit signals without the use of electrical components to boost or regenerate the signal. The network equipment's host handles signal amplification and conditioning. Typically, passive DAC cables are limited to a maximum length of seven meters, as their performance diminishes over longer distances.
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Active DAC cables—Active DAC cables, in contrast, include an additional driving chip that conditions the signal, enhancing transmission quality over longer distances. These cables share the same setup as passive DAC cables but provide signal boosting through built-in electronics. Active DAC cables can typically extend up to 10 meters or more, offering a longer reach in compare with passive DAC cables. By offering both passive and active options, DAC cables provide flexible solutions for various network environments, balancing signal integrity with distance requirements.
Active Optical Cable (AOC)
AOC consists of duplex optical fibers with connectors on both ends. AOC utilizes fiber optic transceivers within the connectors, making it more complex and costly in comparison with DAC cables. Unlike passive cables, AOC requires external power to convert optical signals to electrical signals, and also to convert electrical signals back to optical signals. The use of fiber optics in AOC allows for extended reach, supporting longer distances. It makes AOC an ideal choice for high-performance networking where longer cable runs are necessary.
AOC is lightweight in design in comparison with DAC cables. AOCs are immune to electromagnetic interference. It has higher throughput at longer distances in comparison with DACs. With AOCs, you can select your cabling solution considering a variety of form factors, breakout cables and speed options.
AOC cables can be of two types:
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Single-Mode fiber (SMF)—It has a core diameter of 9 microns and supports higher data rates and longer distances with minimal dispersion. The applications include long-distance communication and high-bandwidth transmission.
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Multimode fiber (MMF)—It has a core diameter of 50 or 62.5 microns. It is easier to install and align but has higher attenuation and dispersion than SMF, making it suitable for shorter distances. The applications include short to medium-distance communication, typically within buildings or campuses.
The AOC cables used along with 800GbE transceivers include:
| OSFP | QDD |
|---|---|
Architecture of AOC and DAC Cables
AOC and DAC each use distinct architectures, resulting in different operational characteristics. DAC cables, both active and passive, use copper wires to transmit electrical signals. Passive DAC cables directly transmit signals without any conditioning. Active DAC cables incorporate a driving chip within the transceivers to enhance and condition the signals.
In contrast, AOC cables transform electrical signals into optical signals using fiber optics, requiring external power for this conversion. The optical signals are then converted back to electrical signals at the receiving end. This architecture enables AOC cables to maintain high signal integrity over longer distances.
Cable Length or Range
Juniper 800GbE transceivers support varying cable lengths to meet specific needs. For more information about the specific distance range of individual transceivers, see Hardware Compatibility Tool.