In-depth description of Gigabit Ethernet Switching Technology

The Gigabit Ethernet technology is gradually being upgraded. In addition to its original compatibility, broadband, low cost, and good support for IP addresses, it also features reliability and scalability, there are also many price issues that people are most concerned about, all having a qualitative leap.

Currently, Radio and Television Broadband man hosts IP-based services. The platforms that carry IP addresses mainly include four technologies: ATM, Gigabit Ethernet, POS, and DPT. This article will not compare the IP addresses hosted by ATM and Gigabit Ethernet, but will discuss this topic in another article. POS was originally used to carry IP addresses on SDH over a WAN. It can also be used to explore optical fiber networks in man networks. DPT is CISCO's proprietary man technology.

Ethernet: 802.3 defines a 10 Mbps Ethernet standard and uses the carrier listener and Conflict Detection CSMA/CD protocol to run in half duplex mode. Since the end of 1980s, Ethernet has achieved great success. 10BaseT is an Ethernet running on 3 or higher categories of twisted pair wires.

10Base2/5 is the Ethernet that runs on the coaxial cable, and 10BaseFL is the Ethernet that runs on the optical fiber. Because the protocol for conflict detection requires a 512-bit time slot to ensure that no conflict is detected, the Ethernet distance coverage is limited. The maximum coverage distance of 10 basefl is 2 km, the maximum coverage distance of 10BaseT in a network segment is 100 m.

Fast Ethernet: 802.3u defines a Mbps Fast Ethernet standard. It can run the CSMA/CD protocol in half duplex mode or in full duplex mode. Due to the backward compatibility of Fast Ethernet to Ethernet, in the middle and late 1990s S, Fast Ethernet became the mainstream technology in LAN.

100BaseTX is a fast Ethernet running on Category 5 twisted pair wires, and 100BaseFX is a fast Ethernet running on optical fibers. For Fast Ethernet that runs in half duplex mode, there is also a limit on the distance to the coverage, and because of the Fast Ethernet operates at a rate of Mbps.

The length of the time slot is also 512 bits, so its maximum distance is 1/10 m of Ethernet. However, in theory, there is no longer a limit on the full-duplex Fast Ethernet, but it is actually limited by the attenuation of electrical or optical signals. The full-duplex Fast Ethernet of 100 BasFX SMF running on a single-mode optical fiber can reach a maximum coverage distance of more than 20km.

The efficiency of half-duplex Ethernet has always been a weakness. After the number of workstations such as computers in a half-duplex Ethernet is increased to a certain threshold value, even though each workstation sends data at a rate of 10 Mbps, however, the conflict increases.

Each workstation has to wait a long time before it can send data, so the average available bandwidth of each workstation is greatly reduced. In full-duplex switched Ethernet, the CD conflict detection mechanism in the CSMA/CD protocol is no longer needed, and each workstation can obtain an exclusive bandwidth. Therefore, the efficiency of full-duplex switched Ethernet is not determined by the number of workstations in the network, but by the length of the Ethernet frame.

Multiple Gigabit Ethernet key channels in Port aggregation can achieve load balancing. Even if the optical fiber of one of the links fails, the logical link will continue to work normally. Port gathering requires a large amount of optical fiber. The aggregation of two ports requires four optical fiber cables, and the aggregation of three ports requires six optical fiber cables, eight optical fiber cables are required for the gathering of four ports.

1.4.2 The same 1 + 1 backup of Gigabit Ethernet is similar to the 1 + 1 backup of the physical link of the ATM implemented by many ATM switches. The Gigabit Ethernet can also achieve 1-10 backup, that is, the interface module of a gigabit route switch corresponds to a Gigabit Ethernet key. Actually, two Gigabit Ethernet links are used for connection, and one gigabit Ethernet link is used as the primary key, the other is used as the backup Key Path.

When the optical fiber of the active link fails, the Gigabit route switch can switch data to the optical fiber of the standby Key Path for transmission within 1 ms. In this 1 + 1 backup mode, four optical fiber cables are required for 1 Gbps transmission bandwidth. Each Gigabit Ethernet link requires one optical fiber and one optical fiber.

If Gigabit Ethernet is used to carry IP services, the convergence feature of IP routing protocol can be applied to ensure the reliability of man. With IP routing, the network topology can be a star, ring, or mesh network, or a combination of them.

Here, we can point out that if IP routing is not used, because of the function of the SPanning Tree Protocol SPanning Tree), Gigabit Networks form a ring or mesh even on physical keys, the actual Ethernet data exchange on the switch cannot constitute a ring or a mesh network.

In the topology of the ring and mesh networks, even if a link or a network node fails, the entire network will not be paralyzed due to the existence of a roundabout route. The most typical IP routing protocol in Man is OSPF. Routers running OSPF use Hello messages to periodically transmit the router status.

When a neighboring node is found to be faulty, the router recalculates the route and automatically finds a roundabout route to ensure that the Network is working properly. This process is called routing convergence. Generally, the OSPF protocol has a convergence time greater than 10 seconds. Compared with the 1-gigabit Ethernet 1 + 1 backup mode, the OSPF protocol takes a long time to recover from faults.

1. Correct Interpretation and test of vswitch Port
2. Summarize the market status of high-end Switches
3. Resolve core layer switch faults
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5. Let's talk about the stacking of Ethernet switches.