Enormous efforts put on the development of high-performance Ethernet technology that provides gigabit-per-second transmission rates have led to the extension of Gigabit products to include the copper Gigabit Ethernet (GbE) standard: 1000BASE-T. Many papers and articles have been attributed to introducing the fiber-optic GbE standards, such as 1000BASE-SX, 1000BASE-LX, 1000BASE-ZX. And contributions are few about 1000BASE-T. This text just helps you to better understand 1000BASE-T and talks about it: a copper GbE solution.
1000BASE-T is also known as IEEE 802.3ab. Just judging from its name, “1000” here means the transmission speed of 1000Mbps. The “BASE” refers to BASE band signaling, indicating that only Ethernet signals are carried on the medium. The “T” represents twisted-pair copper cable (for example Cat 5). More specifically, 1000BASE-T uses four pairs of Cat 5 unshielded twisted pair (UTP) to achieve the Gigabit data rate and achieves 1000Mbps data rates by sending and receiving a 250Mbps data stream over each of the four pairs simultaneously. The distribution of four-pair Cat 5 cabling extends from the work area to the equipment room and between equipment in the equipment room, thus enabling connectivity to switched and shared gigabit services for both high-bandwidth work area computing and server farms.
1000BASE-T is able to provide half-duplex (CSMA/CD) and full-duplex 1000Mb/s Ethernet service over Cat 5 links as defined by ANSI/TIA/EIA-568-A. Besides GbE applications over Cat 5 copper cabling, 1000BASE-T also supports other specifications. First, it supports the Ethernet MAC (Media Access Control), and is backward compatible with a 10/100 Mbps Ethernet. Second, many 1000BASE-T products support 100/1000 auto-negotiation, and therefore 1000BASE-T can be incrementally deployed in a Fast Ethernet network. Third, 1000BASE-T is a high-performing technology with less than one erroneous bit in 10 billion transmitted bits. (10 is the same error rate as that of 100BASE-T.) Topology rules for 1000BASE-T are the same as those used for 100BASE-T.
Why network designers choose 1000BASE-T as the copper GbE solutions? Or put it in another way, what are the advantages of 1000BASE-T?
- Performance—1000BASE-T scales Ethernet 10/100Mbps performance to 1000Mbps. Compared with 1Gbps, 1000BASE-T is 100 times as fast as the standard Ethernet. It permits the smooth migration of the 10/100 networks to 1000 Mbps-based networks. When 1000BASE-T technology is deployed in transceiver modules, these 1000BASE-T SFP transceivers, such as Fiberstore compatible Cisco SFP-GE-T, make shared gigabit service possible and aggregate one gigabit of server support. This Cisco 1000BASE-T SFP supports 1000BASE-T operation in host systems with a compact RJ-45 connector assembly.
- Cost—Used in conjunction with Full Duplex Repeaters (FDRs), 1000BASE-T can provide highly cost-effective shared gigabit service. FDRs offer the traditional low-cost shared media operation of repeaters, but when coupled with 1000BASE-T, they offer an easy-to-manage, high-burst rate, shared-media solution capable of supporting both end users and server farms. In such a case, to aggregate one gigabit of server support is possible in a cost-effective way.
While realizing a 1000Mb/s data stream over four pairs of Category 5 twisted pair cables meet several challenges may meet several challenges, like signal attenuation, echo, return loss, etc.
- Attenuation is the signal loss of the cabling from the transmitter to the receiver. Attenuation increases with frequency, so designers are challenged to use the lowest possible frequency range that is consistent with the required data rate.
- Echo is a by-product of dual-duplex operation, where both the transmit and receive signal occupy the same wire pair. The residual transmitted signal because of the trans-hybrid loss combines with the cabling return loss to produce an unwanted signal referred to here as echo.
- Return loss is a measure of the amount of power reflected due to cabling impedance mismatches.
1000BASE-T technology is the ideal high-speed solution for these application when 1000BASE-T uplinks from desktop switches to aggregating switches. Many network designers have chosen this copper GbE solution for high network performance in a cost-effective way. Fiberstore supplies many 1000BASE-T SFPs which are fully compatible with major brands, like Cisco GLC-T and SFP-GE-T mentioned above. For more information about 1000BASE-T SFPs, you can visit Fiberstore.