1. Modern Ethernet
Chapter 5

2. Objectives
• Describe the varieties of 100-megabit
Ethernet
• Discuss copper- and fiber-based Gigabit
Ethernet
• Compare the competing varieties of 10-
Gigabit Ethernet

3. Overview

4. Three Parts to Chapter 5
• 100-megabit Ethernet standards
• Gigabit Ethernet standards
• 10-Gigabit Ethernet standards

5. Ethernet Facts
• There are only four Ethernet speeds: 10 mega-
bit, 100 megabit, 1 gigabit, and 10 gigabit
• Every version of Ethernet uses either unshield-
ed twisted pair (UTP) or fiber-optic. (With a few,
rare exceptions)
• Every version of Ethernet uses a hub or switch,
although hubs are incredibly rare today.

6. Ethernet Facts (continued)
• Only 10- and 100-megabit Ethernet may use a
hub. Gigabit and 10-Gigabit Ethernet networks
must use a switch.
• Every version of Ethernet has a limit of 1024
nodes.
• Every UTP version of Ethernet has a maximum
distance from the switch or hub to the node of
100 meters.

7. 100-Megabit Ethernet

8. • 100BaseT
– 100BaseT4
• CAT 3 or better cabling
• Uses all four pair of wires
• Disappeared from the market after 100BaseTX
generally accepted
– 100BaseTX
• Dominant 100-megabit standard by the late 1990s
• The term “100BaseT” now applies to this standard

9. • 100BaseTX Summary
– Speed: 100 Mbps
– Signal type: Baseband
– Distance: 100 meters between the hub and the
node
– Node limit: No more than 1,024 nodes per hub
– Topology: Star bus topology: physical star, logical
bus
– Cable type: Uses CAT5(e) or better UTP cabling with
RJ-45 connectors

10. • Upgrading 10BaseT network to 100BaseT
– CAT 5 cable or better
– Replace all old 10BaseT NICs with 100BaseT NICs
– Replace 10BaseT hubs or switches with 100BaseT
hubs or switches
– Multispeed, auto-sending NICs and
hubs/switches ease the upgrade

11. • Multispeed, autosensing NIC
– When first connected, it negotiates automatically
with the hub or switch
– If both do 100BaseT, they will use that mode
– If the hub/switch only does 10BaseT, NIC does
10BaseT

12. Figure 5.1 Typical 100BaseT NIC

13. Figure 5.2 Auto-negotiation in action

14. • Distinguishing 10BaseT NIC from 100BaseT NIC
– Inspect closely
– Look for something indicating the card’s speed
– All modern NICs are multispeed and auto-sensing

15. Figure 5.3 Typical 100BaseT NIC in Vista

16. • 100BaseFX
– UTP versus fiber-optic
• UTP cannot meet the needs of every organization
– 100-meter distance limit inadequate for
large buildings and campuses
– Lack of electrical shielding
– Easy to tap
– Fast Ethernet refers to all the 100-Mbps Ethernet
standards

17. • 100BaseFX Summary
– Speed: 100 Mbps
– Signal type: Baseband
– Distance: Two kilometers between hub and
node
– Node limit: No more than 1,024 nodes per hub
– Topology: Star bus topology: physical star,
logical bus
– Cable type: Uses multimode fiber cabling with
ST or SC connectors

18. • Full-Duplex Ethernet
– Early 100BaseT NICs were half-duplex
• Could both 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
– NIC and hub/switch determine full-or-half
duplex
– Setting can be forced through the operating
system

19. Figure 5.4 Half-duplex; sending at the top,
receiving at the bottom

20. Figure 5.5 Full-duplex

21. Figure 5.6 Forcing speed and duplex in Windows Vista

22. Gigabit Ethernet

23. • IEEE 802.3ab called 1000BaseT
– Most dominant Gigabit Ethernet
– Four-pair UTP
– Maximum cable length 100 meters
– Connectors and ports look exactly like 10BaseT,
100BaseT

24. • IEEE 802.3z known as 1000BaseX
– 1000BaseCX
• Twinaxial cable
– Shielded 150-Ohm
– Maximum length of 25 meters
• This standard made little progress

25. Figure 5.7 Twinaxial
cable

26. • IEEE 802.3z (continued)
– 1000BaseSX
• More common
• Multimode fiber-optic cable
• Maximum cable length 200 to 500 meters,
depending on manufacturer
• Uses 850-nm wavelength LED
• Devices look exactly like 100BaseFX products
• SC is the most common type of connection

27. • IEEE 802.3z (continued)
– 1000BaseLX
• Long distance carrier
• Single-mode (laser) cables
• Maximum cable length 5 kilometers
• Special repeaters increase distance to 70
kilometers!
• Positioned as the Ethernet backbone of the future
• Connectors look like 100BaseSX connectors

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

29. • New Fiber Connectors (continued)
– Solution: Small Form Factor (SFF)
connectors
• Mechanical Transfer Registered Jack (MT-RJ)
• Local Connector (LC)
– Very popular
– Considered the predominant fiber connector
• Other fiber connectors exist
• Only standards are ST and SC
• Manufacturers have different connectors

30. Figure 5.8 MT-RJ connector

31. Figure 5.9 LC-type connector

32. Table 5.1 Gigabit Ethernet Summary
Standard Cabling Cable Details Connectors Length
1000BaseCX Copper Twinax Twinax 25 m
1000BaseSX Multimode 850 nm Variable – 220 – 500 m
fiber SC is
common
1000BaseLX Single- 1,300 nm Variable – 5 km
mode fiber LC, SC are
common
1000BaseT CAT 5e/6 Four-pair / RJ-45 100 m
UTP full-duplex

33. 10-Gigabit Ethernet

34. • Introduction to 10-Gigabit Ethernet (10-
GbE)
– Showing up in high-level LANs
– Expected to trickle down to the desktops
in near future
– New technology
– Large number of fiber standards
– Two copper standards
– 10-GbE copper product available only
since 2008

35. • Fiber-base 10-GbE
– IEEE challenge
• Maintain the integrity of 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

36. • Fiber-base 10 GbE (continued)
– IEEE Actions
• A set of 10GbE standards using traditional LAN
Physical-layer mechanisms
• A set of 10 GbE standards using SONET
infrastructure over WAN fiber
• Recognized need for different networking
situations

37. • IEEE created several standards defined
by
– The type of fiber used
– The wavelength of the laser or lasers
– The Physical layer signaling type
– Maximum signal distance (defined by
previous factors)

38. • Naming convention begins with
10GBasexy
– x = type of fiber (usually) and the signal
wavelength
– y = Physical layer signaling standard
• R for LAN-based signaling
• W for SONET/WAN-based signaling

39. • 10GBaseSy uses a short-wavelength
(850 nm) signal over multimode
Standard Fiber Type Wavelength Physical Maximum
Layer Signal
Signaling Length
10GBaseSR Multimode 850 nm LAN 26-300 m
10GBaseSW Multimode 850 nm SONET/WAN 26-300 m
Fiber-based 10GBaseSy Summary

40. Figure 5.10 A 10GBaseSR NIC
(photo courtesy of Intel Corporation)

41. • 10GBaseLy uses a long-wavelength
(1310 nm) signal over single-mode
Standard Fiber Type Wavelength Physical Maximum
Layer Signal
Signaling Length
10GBaseLR Single-mode 1310 nm LAN 10 km
10GBaseLW Single-mode 1310 nm SONET/WAN 10 km
Fiber-based 10GBaseLy Summary

42. • 10GBaseEy uses an extra-long-wave-
length (1550 nm) signal over single-
mode fiber
Standard Fiber Type Wavelength Physical Maximum
Layer Signal
Signaling Length
10GBaseER Single-mode 1550nm LAN 40 km
10GBaseEW Single-mode 1550 nm SONET/WAN 40 km
Fiber-based 10GBaseEy Summary

43. • 10 GbE connectors
– Standards do not define the type of
connector
– Manufacturers determine connectors

44. • Copper-based 10GbE (10GBaseT)
– 2006: IEEE standard for 10GbE 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 to go to
100 meters

45. Table 5.2 10-GbE Summary
Wavelength /
Standard Cabling Cable Details Connectors Length
10GBaseSR Multimode 850 nm Not defined 26 – 300 m
/SW fiber
10GBaseLR Single- 1310 nm Variable – LC 10 km
/LW mode fiber is common
10GBaseER Single- 1550 nm Variable – LC, 40 km
mode fiber SC are
common
10GBaseT CAT 6/6a Four-pair / RJ-45 55 – 100 m
UTP full-duplex

46. • 10-GbE Physical Connections
– Hodgepodge of 10-GbE types
– Problem: single router may need to support
several connector types
– Solution: multisource agreement (MSA)
• Modular transceiver plugs into10-GbE equipment
• Converts between media types
• Many competing media types recently
– 10-GbE equipment exclusive domain of high-
bandwidth LANs and WANs, including the Internet

47. Figure 5.11 XENPAK MSA

48. • Backbones
– Multispeed network works best for many
situations
– Series of high-speed switches create a
backbone
• No computers (except maybe servers) on the backbone
• Each floor has its own switch connecting to every node
on floor
• Each floor switch has a separate high-speed
connection to a main switch

49. Figure 5.12 Typical network configuration
showing backbone

50. Figure 5.13 Switches with dedicated, high-speed
add-on ports

51. • Know Your Ethernets!
– Know details of the Ethernet versions
– Use summaries and tables
– So far in the text, only the functions of a
basic switch have been explained
– More to see in terms of capabilities of
switches