Jacket, in networking, is the outer covering of cabling that protects it from physical damage. To learn more, read the full article.

What is Jacket (in computer networking)?

The outer covering of cabling that protects it from physical damage. The jacket of a cable protects the wiring from various kinds of damage, including:

• Damage caused by exposure to sun, heat, moisture, dust, and chemicals
• Damage caused by contact with sharp edges of walls, furniture, or plenum ducts; by mechanical vibrations; or by mechanical stresses introduced during the cable installation process

The jacket is usually made of an insulating material, although its primary purpose is not insulation. (This function is provided by the insulation of individual wires within the jacket.) Common materials used for cable jackets include the following:

• Polyvinyl chloride (PVC): This is the most common material used for cable jackets. PVC is a tough, fire-resistant material formed from resins and plastics that can withstand a wide range of temperatures. PVC cables are typically used in vertical rises, but they should not be used in plenums because PVC gives off toxic fumes when burned. 
• Kynar plastic (polyvinylidene fluoride): This material has good fire-retardant qualities, which makes it suitable for installation in plenums, but it is several times more costly than polyvinyl chloride. 
• Flamarrest: This chloride compound has high fire retardance and is suitable for plenum installations. 
• Neoprene: This dark-colored plastic is resistant to moisture and doesn’t degrade in sunlight. It’s a good choice for use in outdoor cable runs. 
• Polyethylene: This soft, moisture-resistant plastic has poor fire retardance and is suitable only for outdoor cable runs.