Modern Ethernet Chapter 5

Objectives Describe the varieties of 100-megabit Ethernet Discuss copper- and fiber-based Gigabit Ethernet Discover and describe Ethernet varieties beyond Gigabit

Test Specific 100-Megabit Ethernet

100-Megabit Ethernet The quest to break 10-Mbps network speeds in Ethernet started in the early 1990s Goal: create new speed standard with no change to Ethernet frames themselves Two defining characteristics of Ethernet remain the same as speed increases Frame size and elements Method of sharing access to the bus Exam Tip (p. 85): CompTIA uses some seemingly sloppy language to describe CDMA in the competencies, calling it carrier detect/sense. You know what the technology means, so don’t miss this stuff on the exam. Cross Check: Interconnecting Ethernet Networks (p. 85) You learned about the devices used to connect different types of Ethernet networks—hubs and switches—in Chapter 3. Check your memory now. What’s the difference between the two devices? Which would you prefer for connections and why?

100BaseT 100BaseT4 100BaseTX CAT 3 or better cabling Uses all four pair of wires Disappeared after 100BaseTX was accepted 100BaseTX CAT 5 cabling Dominant 100-megabit standard by the late 1990s The term “100BaseT” now applies to this standard Note (p. 85): 100BaseT was at one time called Fast Ethernet. The term still sticks to the 100-Mbps standards even though there are now much faster versions of Ethernet.

100BaseTX (100BaseT) Summary Speed: 100 Mbps Signal type: Baseband Distance: 100 meters between hub and node Node limit: 1024 nodes per hub Topology: Star-bus topology: physical star, logical bus Cable type: CAT5(e) or better; UTP or STP cabling with RJ-45 connectors Exam Tip (p. 86): A baseband network means that only a single signal travels over the wires of the network at one time, occupying the lowest frequencies. Ethernet networks are baseband. Contrast this with broadband, where you can get multiple signals to flow over the same wire at the same time, modulating to higher frequencies. This is how cable television and cable Internet works.

Upgrading the Network Upgrading 10BaseT network to 100BaseT CAT 5 cable or better Replace old 10BaseT NICs with 100BaseT NICs Replace 10BaseT hub or switch with 100BaseT hub or switch Multispeed, auto-sending NICs and hubs/switches ease the upgrade

Lingo Multispeed, auto-sensing 100BaseT NIC: 10/100 When first connected, it negotiates automatically with the hub or switch to determine other device’s highest speed Operates at lowest speed both can handle Tech Tip: Lingo (p. 86) If you want to sound like a proper tech, you need to use the right words. Techs don’t actually say, “multispeed, auto-sensing,” but rather “10/100.” As in, “Hey, is that a 10/100 NIC you got there?” Now you’re talking the talk!

Figure 5.1 Typical 100BaseT NIC

Figure 5.2 Auto-negotiation in action

10BaseT versus 100BaseT Distinguishing 10BaseT NIC from 100BaseT NIC Look for something indicating the card’s speed Some NICs have extra link lights to indicate speed Install card, and see what the operating system recognizes All modern NICs are multispeed and auto-sensing Exam Tip (p. 87): There’s no scenario where you’d deploy any 10-megabit networking hardware today, including 10Base2 or 10BaseT. Not sure why the Network+ competencies reference such old technologies in such a fashion.

Figure 5.3 Typical 100BaseT NIC in Windows 8.1

100BaseFX Combined the high speed of 100-megabit Ethernet with fiber optic reliability UTP versus fiber-optic UTP cannot meet the needs of every organization 100-meter distance limit is inadequate for large buildings and campuses Lack of electrical shielding Easy to tap Offers improved data speeds over 10BaseFL Tech Tip: Shielded Twisted Pair (p. 87) Installing networks in areas of high electrical interference used to require the use of shielded twisted-pair (STP) cabling rather than UTP. Even though you can still get STP cabling, its use is rare today. Most installations use fiber-optic cable in situations where UTP won’t cut it. The exception to this rule is with relatively short cable runs through high-noise areas, like in a workshop. Swapping out a UTP cable with an STP cable is simpler and much less expensive than running fiber and changing NICs as well.

100BaseFX Summary Speed: 100 Mbps Signal type: Baseband Distance: Two kilometers between hub and node Node limit: 1024 nodes per hub Topology: Star-bus topology: physical star, logical bus Cable type: Multimode fiber-topic cabling with ST or SC connectors Note (p. 87): The Fiber Distributed Data Interface (FDDI) flourished on college campuses during the 1990s because it could cover long distances and transfer data at the (then) blazing speed of 100 Mbps. FDDI used fiber optic cables with a token bus network protocol over a ring topology. Fast Ethernet over UTP offered a much cheaper alternative when it became available, plus it was completely compatible with 10BaseT, so FDDI faded away.

Full-Duplex Ethernet Early 100BaseT NICs were half-duplex Could send and receive data but not at the same time IEEE added full-duplex to the standard Device sends and receives at the same time By late 1990s, most 100BaseT cards could auto-negotiate for full-duplex Almost all NICs today support full-duplex

Figure 5.4 Half-duplex: sending at the top, receiving at the bottom

Note (p. 88): Full-duplex doesn’t increase network speed directly, but it doubles network bandwidth. Imagine a one-lane road expanded to two lanes while keeping the speed limit the same. And if you recall from the previous chapter, going full-duplex disables CSMA/CD and eliminates collisions. Figure 5.5 Full-duplex

Figure 5.6 Forcing speed and duplex in Windows 8.1

Gigabit Ethernet

Gigabit Ethernet Most common Ethernet type found on new NICs 1000BaseT Most widely implemented solution Four-pair UTP or STP cabling Maximum cable length 100 meters per segment Connectors and ports look exactly like 10BaseT and 100BaseT Exam Tip (p. 88): The TIA/EIA published the 1000BaseTX standard in 2001 to compete with 1000BaseT. Although simpler to implement, it required CAT 6 cabling, which was wildly expensive compared to CAT 5e at that time. 1000BaseTX died an early death, but still lives on, zombie like, on the CompTIA Network+ exam. Note (p. 89): The term Gigabit Ethernet is more commonly used than 1000BaseT.

1000BaseCX Twinaxial cable This standard made little progress Shielded 150-ohm Maximum length of 25 meters This standard made little progress

Figure 5.7 Twinaxial cable

1000BaseSX More common Multimode fiber-optic cable Maximum cable length 220 to 500 meters, depending on manufacturer Uses 850-nm wavelength LED Devices look similar to 100BaseFX products LC is the most common type of connection Exam Tip (p. 89): The wavelength of a particular signal (laser, in this case) refers to the distance the signal has to travel before it completes its particular shape and starts to repeat. The different colors of the laser signals feature different wavelengths. Cross Check: SC and ST (p. 89) You learned about the common fiber-optic cable SC and ST connectors way back in Chapter 3, so cross-check your knowledge here. What distinguishes the two connectors? Can 100BaseFX NICs use either one? Which do you need to twist like a bayonet?

1000BaseLX Long-distance carrier Single-mode (laser) cables Maximum cable length 5 kilometers Special repeaters increase distance to 70 kilometers Positioned as Ethernet backbone of the future Connectors look like 100BaseSX connectors

Problems with ST and SC Connectors ST connectors are relatively large, twist-on Installer must twist cable—danger of fracturing fibers Techs have trouble getting fingers around closely packed connectors SC connectors snap in/out but are also large Manufacturers wanted smaller connectors for more ports

SFF Connectors Mechanical Transfer Registered Jack (MT-RJ) Local Connector (LC) Very popular, especially in United States Considered the predominant fiber connector Other fiber connectors exist (ST/SC standards) Fiber equipment manufacturers may have different connections

Figure 5.8 MT-RJ connector

Figure 5.9 LC-type connector

Mechanical Connection Variations Fiber connectors vary at the connection point Physical Contact (PC) connector Standard connector type today Two pieces of fiber touch when inserted Reduces signal loss at connection point Replaces older flat-surface connector

UPC and APC Connectors Ultra Physical Contact (UPC) connectors Extensively polished to significantly reduce signal loss Angled Physical Contact (APC) connectors Eight-degree angle on the curved end lowers signal loss further Connection does not degrade from multiple insertions

Implementing Multiple Types of Gigabit Ethernet Devices often capable of supporting more than one type of Ethernet Media converters can connect different types of Ethernet cabling together Single-mode fiber (SMF) to UTP/STP Multimode fiber (MMF) to UTP/STP Fiber to coaxial SMF to MMF Exam Tip (p. 91): The CompTIA Network+ exam competencies erroneously describe some media converters as single-mode fiber to Ethernet and multimode fiber to Ethernet. It’s all Ethernet! Don’t be surprised if you get one of those terms on the exam, however. Now you’ll know what they mean

GBICs and SFPs Gigabit interface converter (GBIC) Modular port Use example: replace an RJ-45 port GBIC with an SC GBIC Small form-factor pluggable (SFP) Smaller modular connector Used on current-era switches and other network equipment Hot swappable Note (p. 91): Interestingly, the CompTIA Network+ objectives mention SFPs and GBICs, but only when troubleshooting failed ones. I’ll cover them in a little more detail, therefore, in the network troubleshooting chapter.

10 Gigabit Ethernet

10 Gigabit Ethernet (10 GbE) Showing up in high-level LANs A number of fiber standards and two copper standards

Fiber-Based 10GbE Challenges Maintain integrity of the Ethernet frame How to transfer frames at high speeds Could use traditional Ethernet physical layer mechanisms Already a usable ~10 GbE fiber network (SONET) used for WANs Note (p. 92): Chapter 14 covers SONET in great detail. For now, think of it as a data transmission standard that’s different from the LAN Ethernet standard.

Fiber-Based 10 GbE Standards Defined by: Type of fiber used Laser wavelength Physical layer signaling type IEEE standard names in format 10GBasexy x represents type of fiber and wavelength y represents physical layer signaling standard Either R for LAN-based signaling or W for SONET/WAN

Fiber-Based 10GBaseSy Summary 10GBaseSy uses a short-wavelength (850 nm) signal over multimode

Fiber-Based 10GBaseLy Summary 10GBaseLy uses a long-wavelength (1310 nm) signal over single-mode Exam Tip (p. 92): The 10GBaseLRM specification offers similar speeds and specs as other 10GBaseLy options, but uses multimode rather than single-mode fiber. This drops the distances down to 220 meters for most variations.

Fiber-based 10GBaseEy Summary 10GBaseEy uses an extra-long-wave-length (1550 nm) signal over single-mode fiber Tech Tip: The Other 10 Gigabit Ethernet Fiber Standards (p. 93) Manufacturers have shown both creativity and innovation in taking advantage of both existing fiber and the most cost-effective equipment. This has led to a variety of standards that are not covered by the CompTIA Network+ competencies, but that you should know about nevertheless. The top three as of this writing are 10GBaseL4, 10GBaseRM, and 10GBaseZR. The 10GBaseL4 standard uses four lasers at a 1300-nanometer wavelength over legacy fiber. On FDDI-grade multimode cable, 10GBaseL4 can support up to 300-meter transmissions. The range increases to 10 kilometers over single-mode fiber. The 10GBaseLRM standard uses the long wavelength signal of 10GBaseLR but over legacy multimode fiber. The standard can achieve a range of up to 220 meters, depending on the grade of fiber cable. Finally, some manufacturers have adopted the 10GBaseZR “standard,” which isn’t part of the IEEE standards at all (unlike 10GBaseL4 and 10GBaseLRM). Instead, the manufacturers have created their own set of specifications. 10GBaseZR networks use a 1550-nanometer wavelength over single-mode fiber to achieve a range of a whopping 80 kilometers. The standard can work with both Ethernet LAN and SONET/WAN infrastructure.

Copper-Based 10 GbE (10GBaseT) 2006: IEEE standard for 10 GbE running on UTP Looks and works like slower versions of UTP Ethernet Downside: 10GBaseT running on CAT 6 has maximum cable length of only 55 meters 10GBaseT running on CAT 6a can go to 100 meters

10 GbE Physical Connections Hodgepodge of 10 GbE types Problem: single router may need to support several types of physical media and connector Solution: multisource agreements (MSAs) MSA transceiver plugs into 10 GbE equipment Converts between media types 10 GbE equipment is the exclusive domain of high-bandwidth LANs and WANs

Exam Tip (p. 94): One of the currently most popular transceivers used in 10 GbE is called the enhanced small form-factor pluggable (SFP+). But you won’t see it on the current Network+ exam. Figure 5.10 XENPAK module

Backbones Multispeed Ethernet works best for many situations Series of high-speed switches create a backbone No computers (except maybe servers) attach directly to the backbone Each floor has its own switch connecting to every node on floor, and a separate high-speed connection to a main switch

Figure 5.11 Typical network configuration showing backbone

Figure 5.12 Switches with dedicated, high-speed ports Try This! Shopping for Switches (p. 95) Cisco, one of the industry leaders for Ethernet switches, has a great Web site for its products. Imagine that you are setting up a network for your school or business (keep it simple and pick a single building if you’re in a large organization). Decide what type of switches you’d like to use, including both the backbone and local switches. If you’re really motivated, decide where to locate the switches physically. Don’t be afraid to try a fiber backbone—almost every Cisco switch comes with special ports to enable you to pick the type of Ethernet you want to use for your backbone. Figure 5.12 Switches with dedicated, high-speed ports

Beyond Network+

IEEE 802.3ba Committee approved standards for 40-Gb and 100-Gb Ethernet in 2010 Use the same frame as earlier versions of Ethernet Primarily implemented in backbones and machine-to-machine connections