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Multi-Gigabit Ethernet

Multi-Gigabit Ethernet, defined in IEEE 802.3bz, is one of the latest Ethernet technologies. It is one of the latest Ethernet technologies. It aims to provide higher bandwidth than 1 Gbit/s, but still allows the use of the existing Cat5e/Cat6 cable infrastructure to meet the requirements of modern enterprise networks for higher bandwidth.

Why Is Multi-Gigabit Ethernet Required?

Since the birth of Ethernet in the 1970s, driven by market demands, the Institute of Electrical and Electronics Engineers (IEEE) has quickly promoted the establishment of Ethernet standards such as Fast Ethernet (100 Mbit/s), Gigabit Ethernet (1000 Mbit/s), 10 Gigabit Ethernet (10 Gbit/s), and 100 Gigabit Ethernet (100 Gbit/s).

With the rapid development of network technologies, enterprise networks and even home networks have increasing requirements on data transmission rates. The popularity of WLANs and smart terminals has also increased the usage of smartphones, tablets, and IoT devices. With the continuous usage of powerful mobile devices and the transmission of rich content (such as HD videos) by cloud-based applications, the mainstream Gigabit Ethernet is rapidly becoming a bottleneck for enterprise and home networks. The most effective solution is to upgrade the Ethernet bandwidth to 10 Gbit/s.

However, Cat5e and Cat6 twisted pair cables are deployed in most enterprise network environments, and cannot support a transmission rate of 10 Gbit/s. If the Ethernet bandwidth is upgraded to 10 Gbit/s, the cables need to be upgraded at the same time. As a result, the network reconstruction cost is high.

Table 1-1 Rate specifications supported by different cables

Cable Type

Maximum Transmission Rate at 100 m

Cat5

1 Gbit/s

Cat5e

2.5 Gbit/s

Cat6

5 Gbit/s

Cat6a

10 Gbit/s

To solve the preceding problems, the Multi-Gigabit Ethernet standard IEEE 802.3bz emerges and provides two rate specifications: 2.5 Gbit/s and 5 Gbit/s. Multi-Gigabit Ethernet complies with the bandwidth features of Cat5e and Cat6 cables. In this way, Multi-Gigabit Ethernet is compatible with mainstream Cat5e and Cat6 cables on the existing network during a network upgrade, making Multi-Gigabit Ethernet an important technology.

Birth and Key Technologies of Multi-Gigabit Ethernet

Birth of Multi-Gigabit Ethernet

The IEEE 802.3an-2006 standard defines the 10GBASE-T Ethernet standard to specify the network technology required to support transmission at a rate of up to 10 Gbit/s. The launch of 10GBASE-T is more gradual than previous Ethernet revisions, partially because of the relatively high cost per port of the new technology, but mainly because the Cat5e/Cat6 cable infrastructure cannot fully support the standard. 10GBASE-T requires the adoption of an upgraded cable standard Cat6a, which means that enterprises will face huge costs when it comes to replacing existing cable infrastructure.

To solve this problem, many industry companies, including Cisco, Aquantia, NXP, and Intel, established the NBASE-T alliance in 2014 to launch two specifications for intermediate transmission rates: 2.5GBASE-T and 5GBASE-T.

The NBASE-T specifications have been ratified by the IEEE and released in the new standard IEEE 802.3bz. This new standard enables enterprises to leverage existing cable investments and replace devices at both ends of cables with new devices that comply with the IEEE 802.3bz standard. In this way, enterprises can continue to use Cat5e and Cat6 cables while increasing bandwidth by up to five times.

MIMO Technology of Multi-Gigabit Ethernet

Multi-Gigabit Ethernet increases bandwidth by adding more data channels to existing Ethernet hardware. Each channel can transmit data independently, which increases the overall data transmission rate. In Ethernet technologies, these channels are called multiple-input multiple-output (MIMO) channels.

Multi-Gigabit Ethernet also uses more advanced modulation technologies, such as pulse-amplitude modulation with 16 discrete levels (PAM-16), to allow more data to be transmitted on each channel. The use of this technology enables Multi-Gigabit Ethernet to provide a higher rate than traditional Ethernet on the same physical cabling.

PHY Technology of Multi-Gigabit Ethernet

Compared with Gigabit Ethernet, Multi-Gigabit Ethernet needs to provide higher rates on network cables and resist higher signal loss and interference. This requires more complex digital signal processing algorithms and analog front-end technologies with higher bandwidth and linearity.

The low-density parity check (LDPC) error correction code algorithm used by PHY technology of Multi-Gigabit Ethernet is one of the commercially available physical-layer error correction code algorithms with the highest coding gain in the world. The LDPC error correction code algorithm can reduce the bit error rate at the physical layer to a value lower than 1E-12. In this way, the link is highly reliable and no packet loss occurs for a long time. In addition, to avoid the bit error propagation problem of the traditional decision feedback equalizer (DFE), the Tomlinson-Harashima precoding (THP) and soft decision method is used to further reduce the bit error rate.

To transmit more data over the limited bandwidth of network cables, 2.5 Gbit/s and 5 Gbit/s Ethernet networks use PAM-16 higher-order modulation, compared with PAM-5 modulation of Gigabit Ethernet. Higher-order modulation can carry more bits in the frequency bandwidth per Hz, but this also poses higher requirements on the linearity and system noise of the analog front end.

In addition, to improve the bandwidth utilization of the four pairs of network cables, PHY technology of Multi-Gigabit Ethernet uses co-frequency co-time full duplex (CCFD) technology. That is, the master-slave and slave-master signals are transmitted on the same pair of differential cables at the same time and at the same frequency. Compared with the traditional time division system or frequency division system, this transmission mode has about twice the information transmission efficiency.

In addition to data transmission, PHY technology of Multi-Gigabit Ethernet also provides mechanisms such as anti-electromagnetic interference, fast retrain (FR), and adaptive rate negotiation to enable devices to work in more diversified environments.

PoE Power Supply of Multi-Gigabit Ethernet

One of the main application scenarios of Multi-Gigabit Ethernet is the backhaul of WLAN AP data. In actual device deployment, APs need to be powered on. However, APs are often deployed on ceilings or walls, and it is difficult to provide power to them. If separate power cables are connected to APs, the construction and maintenance costs of campus networks will increase. Therefore, power supply to devices over Ethernet is particularly important.

Power over Ethernet (PoE) technology allows a network cable to provide power to a device while transmitting data, without affecting normal data transmission. Currently, there are three PoE standards: IEEE 802.3af (PoE), IEEE 802.3at (PoE+), and IEEE 802.3bt (PoE++).

The Multi-Gigabit Ethernet standard IEEE 802.3bz supports PoE, PoE+, and PoE++ at all data rates, minimizing costs and improving network flexibility.

Huawei Multi-Gigabit Ethernet Switches

Currently, Multi-Gigabit Ethernet has become the best choice for the transition from Gigabit Ethernet to 10 Gigabit Ethernet, and is developing rapidly.

Therefore, Huawei has launched dozens of switches that support the Multi-Gigabit Ethernet standard, such as CloudEngine S5735-S-V2, CloudEngine S5755-H, and CloudEngine S5732-H-V2 series switches. These switches help enterprises upgrade bandwidth without replacing their cable infrastructure. In addition, Huawei Multi-Gigabit Ethernet switches are compatible with multiple IEEE 802.3 Ethernet standards and support Ethernet ports such as 100M/GE/2.5GE/5GE/10GE Base-T ports, implementing flexible rate switching from 100 Mbit/s to 10 Gbit/s.

  • CloudEngine S5735-L-V2 series switches: Based on the next-generation high-performance hardware and software platform, CloudEngine S5735-L-V2 series switches stand out with features including intelligent stack (iStack), flexible Ethernet networking, and diversified security control. These switches support multiple Layer 3 routing protocols and provide higher performance and more powerful service processing capabilities. They are widely used in scenarios such as enterprise campus network access and 2.5GE to the desktop. For more information, see CloudEngine S5735-L-V2 Series 2.5GE Switches.
    CloudEngine S5735-L-V2 <a href='https://info.support.huawei.com/info-finder/encyclopedia/en/Switch.html' title='Switch' rel='noopener noreferrer' data-title='What Is a Switch? What Is It Used for?' data-abstract='A switch enables network communication for connected IT devices. Switches fall into different categories from different perspectives, including Ethernet switches, Layer 3 switches, campus switches, data center switches, core switches, aggregation switches, access switches, fixed switches, and modular switches.'>switch</a>
    CloudEngine S5735-L-V2 switch
  • CloudEngine S5735-S-V2 series switches: Based on the next-generation high-performance hardware and Huawei's unified software platform, CloudEngine S5735-S-V2 series switches provide enhanced Layer 3 features, easy O&M, flexible Ethernet networking, and mature IPv6 features. They are widely used as access and aggregation switches on enterprise campus networks and access switches on data center networks. For more information, see CloudEngine S5735-S-V2 Series 2.5GE Switches.
    CloudEngine S5735-S-V2 switch
    CloudEngine S5735-S-V2 switch
  • CloudEngine S5755-H series switches: Based on the unified Huawei-developed software platform, CloudEngine S5755-H series next-generation high-quality access switches support VXLAN to implement campus network virtualization and multi-purpose network, and provide free mobility to ensure consistent user experience. A switch provides a maximum of 48 downlink ports and supports MACsec on all ports. They are the best choice of access switches for WLAN APs in the Wi-Fi 6 and Wi-Fi 7 era, and are widely used in healthcare, retail, mining, and Internet industries. For more information, see CloudEngine S5755-H Series High-Quality 2.5GE Switches.
    CloudEngine S5755-H switch
    CloudEngine S5755-H switch

    For details about the configuration and maintenance of Multi-Gigabit Ethernet switches, see CloudEngine S5700 and S6700 Product Documentation.

About This Topic
  • Author: Zhang Qimin
  • Updated on: 2024-08-07
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