Difference between Fast Ethernet and Gigabit Ethernet

Fast Ethernet vs Gigabit Ethernet | Standards, physical media specifications, speed and performance

What is Ethernet?

Ethernet in computer networks refers to a set of standards and components that provide support for communicating in a local area network (LAN) between network devices. Different standards have been developed in recent decades. IEEE came with "IEEE 802.3 - Ethernet standard" in the IEEE 802 protocol suite. The original IEEE 802.3 Ethernet standard supports a data rate of 10 megabits per second (Mbps).

With the development of technology, a speed of 10 Mbits / s on the local network was not sufficient. IEEE improved the Ethernet standard “Fast Ethernet” IEEE 802.3u, then came later with the standard “Gigabit Ethernet” IEEE 802.3z.

What is Fast Ethernet ?? 

Fast Ethernet is an improvement on Ethernet, which provides a speed of 100 Mbps. The improvement in speed compared to Ethernet is obtained by reducing the bit time (time required for the transmission of a bit) to 0.01 microseconds. IEEE uses 100BASE-Tx / Rx; as usual, "100" corresponds to the speed of 100 Mbps and "Base" to baseband signals. The following shows the specifications of the physical medium.

Standard Physical environment
100Base-T4 Twisted pair cable - category UTP 3 - maximum segment length 100 m
100Base-TX Twisted pair cable - category 5 UTP or STP - maximum segment length 100 m in full duplex at 100 Mbps
100Base-FX Fiber optic cable - maximum segment length of 2000 m in full duplex at 100 Mbps

100Base-T4 can use four different twisted pairs of Category 3 UTP (unshielded twisted pairs) cables; three pairs back and forth with one pair for CS / CD. It uses 25 MHz signals with 8B / 6T coding. The inter-frame time interval is reduced to 960 nanoseconds, compared to 9.6 microseconds in Ethernet. The maximum distance between two stations is 200 m with the concentrator connected to the center.

100Base-TX uses two pairs of twisted pair cables; one pair for transmission and the other for reception.
100Base-FX is intended for fiber optic support; there are two cables for transmission and reception. It uses FDDI (Fiber Distributed Data Interface) technology to convert the flows of code groups 4B / 5B into NRZI into optical signals at a clock frequency of 125 MHz. 

What is Gigabit Ethernet ?? 

IEEE announced, in February 1997, IEEE 802.3z - Gigabit Ethernet, with other improvements, including Ethernet and Fast Ethernet. Although Gigabit Ethernet uses the same CSMA / CD and Ethernet frame format, there are important differences such as the slot time. As the name suggests, Gigabit Ethernet provides 1000 Mbps full duplex and half duplex transmission. Specifications for the physical medium are listed below. 

Standard Physical environment
1000Base-SX Fiber optic - maximum segment length 550 m, short wavelength
1000Base-LX Fiber optic - maximum segment length 5000 m, long wavelength
1000Base-CX 2 pairs of STP - maximum segment length 25m
1000Base-T 4 pairs of UTP - maximum segment length 100 m

1000Base-SX supports duplex links up to 275 meters, uses a laser wavelength of 850 nm with Fiber Channel technology. This can only be used in multimode fibers with 8B / 10B coding on a 1.25 Gbps line.

1000Base-LX only differs from wavelength greater than 1300nm and more.

1000Base-CX and 1000Base-T use copper wiring and respective distances of 25 to 100 m. 

What is the difference between Fast Ethernet and Gigabit Ethernet ?

  1. The speed of fast Ethernet is 100 Mbits / s, while it is 1000 Mbits / s in Gigabit Ethernet.
  2. We expect better performance and a reduction in bottlenecks thanks to a higher bandwidth in Gigabit Ethernet than in Fast Ethernet. 
  3. Upgrading from Ethernet to Fast Ethernet is simple and less expensive than upgrading Fast Ethernet to Gigabit Ethernet.
  4. Requires specific network devices, capable of supporting a data rate of 1000 Mbps, in Gigabit Ethernet.
  5. Devices connected to Gigabit Ethernet require some manual configuration, while most devices connected to Fast Ethernet configure themselves automatically - negotiate optimal speed and duplex mode.

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