2014年12月22日星期一

Fiber-Based Gigabit Ethernet



The two main laser standards for Gigabit Ethernet over fiber,1000BASE-SX(short wavelength laser) and 1000BASE-LX (long-wavelength laser)
1000BASE-SX
1000BASE-SX operates over multi-mode fiber operating an 850-nm laser, which enables a transmission distance between endpoints of 220 m over 62.5/125-nm fiber.However, consumption of 50/125nm fiber can reliably extend the transmission distance to 500 m, enabling its use like a building backbone.
1000BASE-LX

If their equipment is used at both ends of a connection.When used over multi-mode fiber, a maximum segment length of 550 m is possible, 1000base lx lh sfp represents the long wave laser version of Gigabit Ethernet over fiber.This version of Gigabit Ethernet can be run on single-mode or multi-mode fiber.Single-mode fiber using a 9 um cores and a 1300nm lasers is specified to work over a distance of up to km; however, most vendors support a transmission distance up to 10 to 20km.

Fiber Auto-Negotiation
If the device is 1000BASE-SX or 1000BASE-LX operating in full or half duplex.When auto-negotiation for 1 gaps ethernet occurs, the priority used favors full duplex or either 1000BASE-SX or 1000base-lx over half duplex for either standard, the physical subdivided layers for copper transceiver module , indicating where auto-negotiation is noted in each.This difference results in auto-negotiation capable of being employed at multiple data rates for devices that provide this support; fiber auto-negotiation is limited to negotiation.

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