Ethernet LAN Overview
Ethernet LAN Overview and Types of Ethernet LAN The term Ethernet refers to a family of LAN standards that together define the physical and data link layers of the world’s most popular wired LAN technology. The standards, defined by the Institute of Electrical and Electronics Engineers (IEEE), define the cabling, the connectors on the ends of the cables, the protocol rules, and everything else required to make an Ethernet LAN.
Types of Ethernet LAN
- Typical SOHO LANs
- Typical Enterprise LANs
Typical SOHO LANs
To begin, first think about a small office/home office (SOHO) LAN today, specifically a LAN that uses only Ethernet LAN technology. First, the LAN needs a tool called an Ethernet LAN switch, which provides many physical ports into which cables are often connected. An Ethernet uses Ethernet cables, which may be a general reference to any cable that conforms to any of several Ethernet standards. The LAN uses Ethernet cables to attach different Ethernet devices or nodes to at least one of the switch’s Ethernet ports. Figure 2-1 shows a drawing of a SOHO Ethernet LAN. The figure shows one LAN switch, five cables, and five other Ethernet nodes: three PCs, a printer, and one network device called a router. (The router connects the LAN to the WAN, during this case to the web .)
Although Figure 2-1 shows an easy Ethernet LAN, many SOHO Ethernet LANs today combine the router and switch into one device. Vendors sell consumer-grade integrated networking devices that work as a router and Ethernet switch, also as doing other functions. These devices typically have “router” on the packaging, but many models even have four-port or eight-port Ethernet LAN switch ports inbuilt to the device. Typical SOHO LANs today also support wireless LAN connections. Ethernet defines wired LAN technology only; in other words, Ethernet LANs use cables. However, you’ll build one LAN that uses both Ethernet LAN technology also as wireless LAN technology, which is additionally defined by the IEEE. Wireless LANs, defined by the IEEE using standards that begin with 802.11, use radio waves to send the bits from one node to the next. Most wireless LANs rely on yet one more networking device: a wireless LAN access point (AP). The AP acts somewhat like an Ethernet switch, therein all the wireless LAN nodes communicate with the Ethernet switch by sending and receiving data with the wireless AP. Of course, as a wireless device, the AP doesn’t need Ethernet ports for cables, other than for one Ethernet link to attach the AP to the Ethernet LAN, as shown in Figure 2-2.
Note that this drawing shows the router, Ethernet switch, and wireless LAN access point as three separate devices so that you’ll better understand the various roles. However, most SOHO networks today would use one device, often labeled as a “wireless router,” that does of these functions.
Typical Enterprise LANs
Enterprise networks have similar needs compared to a SOHO network, but on a much larger scale. for instance , enterprise Ethernet LANs begin with LAN switches installed during a wiring closet behind a locked door on each floor of a building. The electricians install the Ethernet cabling from that wiring closet to cubicles and conference rooms where devices might got to connect to the LAN. At the same time, most enterprises also support wireless LANs in the same space, to permit people to roam around and still work and to support a growing number of devices that don’t have an Ethernet LAN interface. Figure 2-3 shows a conceptual view of a typical enterprise LAN during a three-story building. Each floor has an Ethernet LAN switch and a wireless LAN AP. to permit communication between floors, each per-floor switch connects to one centralized distribution switch. for instance , PC3 can send data to PC2, but it might first flow through switch SW3 to the primary floor to the distribution switch (SWD) then back up through switch SW2 on the second floor.
The figure also shows the typical way to connect a LAN to a WAN using a router. LAN switches and wireless access points work to make the LAN itself. Routers connect to both the LAN and therefore the WAN. to attach to the LAN, the router simply uses an Ethernet LAN interface and an ethernet cable, as shown on the lower right of Figure 2-3.
The rest of this chapter focuses on Ethernet in particular.
The Variety of Ethernet Physical Layer Standards
The term Ethernet refers to a whole family of standards. Some standards define the specifics of how to send data over a particular sort of cabling, and at a particular speed. Other standards define protocols, or rules, that the Ethernet nodes must follow to be a part of an Ethernet LAN. of these Ethernet standards come from the IEEE and include the number 802.3 because the beginning a part of the standard name.
Ethernet supports a large sort of options for physical Ethernet links given its long history over the last 40 approximately years. Today, Ethernet includes many standards for various sorts of optical and copper cabling, and for speeds from 10 megabits per second (Mbps) up to 100 gigabits per second (Gbps). The standards also differ as far because the sorts of cabling and therefore the allowed length of the cabling.
The most fundamental cabling choice has got to do with the materials used inside the cable for the physical transmission of bits: either copper wires or glass fibers. the use of unshielded twisted-pair (UTP) cabling saves money compared to optical fibers, with Ethernet nodes using the wires inside the cable to send data over electrical circuits. Fiber-optic cabling, the more expensive alternative, allows Ethernet nodes to send light over glass fibers within the center of the cable. Although more expensive, optical cables typically allow longer cabling distances between nodes.
Also Read:- Overview of the TCP/IP Networking Model
To be able to choose the products to purchase for a new Ethernet LAN, a network engineer must know the names and features of the various Ethernet standards supported in Ethernet products. The IEEE defines Ethernet physical layer standards using a couple of naming conventions. The formal name begins with 802.3 followed by some suffix letters. The IEEE also uses more meaningful shortcut names that identify the speed, also as a clue about whether the cabling is UTP (with a suffix that includes T) or fiber (with a suffix that includes X). Table 2-2 lists a few Ethernet physical layer standards. First, the table lists enough names so that you get a sense of the IEEE naming conventions. It also lists the four commonest standards that use UTP cabling, because this book’s discussion of Ethernet focuses mainly on the UTP options
Consistent Behavior over All Links Using the Ethernet data link Layer
Although Ethernet includes many physical layer standards, Ethernet acts sort of a single LAN technology because it uses an equivalent data link layer standard over all kinds of Ethernet physical links. That standard defines a common Ethernet header and trailer. (As a reminder, the header and trailer are bytes of overhead data that Ethernet uses to try to to its job of sending data over a LAN.) regardless of whether the data flows over a UTP cable or any quite fiber cable, and regardless of the speed, the data-link header and trailer use an equivalent format. While the physical layer standards focus on sending bits over a cable, the Ethernet data-link protocols focus on sending an Ethernet frame from source to destination Ethernet node. From a data-link perspective, nodes build and forward frames. As first defined in Chapter 1, “Introduction to TCP/IP Networking,” the term frame specifically refers to the header and trailer of a data-link protocol, plus the data encapsulated inside that header and trailer. the various Ethernet nodes simply forward the frame, over all the specified links, to deliver the frame to the right destination. Figure 2-4 shows an example of the method . during this case, PC1 sends an Ethernet frame to PC3. The frame travels over a UTP link to Ethernet switch SW1, then over fiber links to Ethernet switches SW2 and SW3, and eventually over another UTP link to PC3. Note that the bits actually travel at four different speeds during this example: 10 Mbps, 1 Gbps, 10 Gbps, and 100 Mbps, respectively.
So, what’s an Ethernet LAN? it’s a combination of user devices, LAN switches, and different sorts of cabling. Each link can use differing types of cables, at different speeds. However, all of them work together to deliver Ethernet frames from the one device on the LAN to another device.
Ethernet LAN Overview and Types of Ethernet LAN The rest of this chapter takes these concepts a little deeper, first looking at the small print of building the physical Ethernet network, followed by some discussion of the principles for forwarding frames through an Ethernet LAN.
Questions related to this topic
- What is the protocol used in Ethernet?
- What is Ethernet and its standards?
- What is an Ethernet explain the different types of Ethernet networks and Ethernet cables?
- How does Ethernet cable transmit data?
- Explain Ethernet LAN Overview and Types of Ethernet LAN?
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