1. Modern Ethernet
Chapter 5

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

3. Test Specific
100-Megabit Ethernet

4. 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?

5. 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.

6. 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.

7. 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

8. 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!

9. Figure 5.1 Typical 100BaseT NIC

10. Figure 5.2 Auto-negotiation in action

11. 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.

12. Figure 5.3 Typical 100BaseT NIC in Windows 8.1

13. 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.

14. 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.

15. 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

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

17. 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 Full-duplex

18. Figure 5.6 Forcing speed and duplex in Windows 8.1

19. Gigabit Ethernet

20. 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.

21. 1000BaseCX Twinaxial cable This standard made little progress
Shielded 150-ohm
Maximum length of 25 meters
This standard made little progress

22. Figure 5.7 Twinaxial cable

23. 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?

24. 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

25. 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

26. 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

27. Figure 5.8 MT-RJ connector

28. Figure 5.9 LC-type connector

30. 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

31. 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

32. 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

33. 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.

34. 10 Gigabit Ethernet

35. 10 Gigabit Ethernet (10 GbE)
Showing up in high-level LANs
A number of fiber standards and two copper standards

36. 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.

37. 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

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

39. 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.

40. 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.

41. 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

43. 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

44. 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 XENPAK module

45. 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

46. Figure 5.11 Typical network configuration showing backbone

47. 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 Switches with dedicated, high-speed ports

48. Beyond Network+

49. 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