RFGigabit Ethernet Explained: Standards and Technologies
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Ethernet technology has seen significant advancements, evolving from its initial 10 Mbps to 100 Mbps and then to 1000 Mbps. The 100 Mbps version is often called Fast Ethernet.
Gigabit Ethernet refers to the type of Ethernet that supports data transfer rates of 1000 Mbps, or 1 Gbps, over both fiber optic and copper cables. This high-speed version of Ethernet is widely used and is specified in the IEEE 802.3z and IEEE 802.3ab standards. These are sometimes referred to as 1000Base-X and 1000Base-T, respectively.
Gigabit Ethernet still utilizes the CSMA/CD access method and supports SNMP tools. The traditional Ethernet frame size ranges from 64 to 1518 bytes, while Gigabit Ethernet also supports jumbo frames with sizes ranging from 64 to 9215 bytes. By using jumbo frames, Gigabit Ethernet reduces the Ethernet frame rate delivered to the host PC. This means fewer collisions and shorter waiting periods compared to the older 10 Mbps Ethernet, resulting in faster transmission times.
The following table summarizes different Gigabit Ethernet standards, the maximum cable lengths supported, and the cable types used:
Gigabit Ethernet Standards
| Ethernet Standard | MAC sub-layer specification | Max. cable length | Cable Type supported | Pairs needed |
|---|---|---|---|---|
| 1000Base-SX | 802.3z | 220 to 550 meter | multimode fiber | 1 |
| 1000Base-LX | 802.3z | 3000 meter | single mode OR multimode fiber | 1 |
| 1000Base-CX | 802.3z | 25 meter | Shielded copper | 2 |
| 1000Base-T | 802.3ab | 100 meter | Category 5 UTP (twisted pair) | 2 |
The 802.3z Gigabit Ethernet standard was introduced in 1998, followed by IEEE 802.3ab in 1999. Later, in 2002, the IEEE 802.3ae standard introduced 10 Gigabit Ethernet.
10 Gigabit Ethernet
This Ethernet type, defined in IEEE 802.3ae specifications, was introduced in 2002. It maintains the same frame size, meaning no changes are needed at Layer 3 and higher protocols. 10 Gigabit Ethernet operates in full duplex mode only, using point-to-point links.
The standard defines two physical layer versions: LAN PHY and WAN PHY, each designed for specific network applications. The WAN PHY provides support for connections to circuit-switched SONET networks.
10 Gigabit Ethernet supports the following interfaces:
10 Gigabit Ethernet Interfaces
| Interface | PHY version | Optical wavelength |
|---|---|---|
| 10GBASE-SR | LAN | 850nm (Serial) |
| 10GBASE-LR | LAN | 1310nm (Serial) |
| 10GBASE-ER | LAN | 1550nm (Serial) |
| 10GBASE-LX4 | LAN | 4-Channel course wave division multiplexing (CWDM), 4x1310nm |
| 10GBASE-SW | WAN | 850nm(Serial) |
| 10GBASE-LW | WAN | 1310nm(Serial) |
| 10GBASE-EW | WAN | 1550nm(Serial) |
10GBASE-R uses a 64B/66B encoding system, running at 10.313 Gbps. 10GBASE-X uses 8B/10B encoding and runs at 3.125 Gbps after encoding.
