GIGABIT ETHERNET BASICS

GIGABIT ETHERNET BASICS

Ethernet is the world's most pervasive networking technology. Gigabit Ethernet is the latest version of Ethernet. It offers 1000 Mbps ( 1 Gbps ) raw bandwidth, that is 100 times faster than the original Ethernet, yet is compatible with existing Ethernets, as it uses the same access (CSMA/CD) and addressing (MAC) protocols.

Gigabit Standards: Standards ensure interoperability between different manufacturer's products.  There are 3 common gigabit standards to choose from.  The choice of what type of gigabit standard to use is based on several factors:

• Distance: Each standard has different distance limitations.  They are listed in the table below.
• Environment: Locations that have electromagnetic interference (EMI) issues should choose to use fiber cabling for their network installation.
• Legacy Cable Installation: If the customer already has a cabling infrastructure installed, every effort should be made to utilize it.  However, gigabit ethernet distance limitations are much shorter than fast ethernet limitations for the same type of fiber cable, so cable replacement may be needed in some situations.
• Future Growth:  The IEEE is working on a standard for 10G Ethernet.  It is predicted that this standard will only work over fiber cabling.  If a customer feels that they will be implementing 10G across their LAN backbone, only fiber cabling should be installed.  The 10G Ethernet Alliance goal is to provide physical layer specifications that support link distances of at least 100m over installed MMF, 300m over MMF as well as over SMF at 2km, 10km and 40km.

** Requires a mode conditioning patch cable (also called launch cable).

Q: Why are there multiple distance specifications for the same fiber-optic cable?

A: There are two distances because there are two standard 62.5 micron multi-mode fibers in the installed cabling base. Much of the installed base of 62.5 micron multi-mode fiber has labeled bandwidth of 160 MHz per km. A growing portion of the installed base of fiber worldwide has a labeled bandwidth of 200 MHz per km. This multi-mode fiber is included in the current international ISO/IEC specification for building cabling. Because this ISO standard multi-mode fiber has a higher bandwidth, it can carry the signal farther.

Extreme differentiator:  Extreme Networks offers more products that support Gigabit Ethernet than any other vendor and they are the world's leading provider of Layer 3 Gigabit Ethernet ports (Dell'Oro).

Mode-conditioning Fiber Patch Cables from Cables To Go!

A mode-conditioning fiber patch cable (also known as a launch cable) is used when a 1000BLX connection needs to connect to a multi-mode fiber cable.  The mode-conditioning cable allows for proper propagation of the laser light along the multi-mode fiber.  Here is a mode conditioning cable that you can use: 

Want to learn more?

• Gigabit Ethernet Alliance White Papers

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