1. Chapter 13 Wired LANs: Ethernet
Topics:
1 – IEEE Standard (Project 802).
2 – Ethernet LANs.
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2. Topics discussed in this section:
IEEE STANDARDS
In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards to enable intercommunication among equipment from a variety of manufacturers. Project 802 is a way of specifying functions of the physical layer and the data link layer of major LAN protocols.
Topics discussed in this section:
Data Link Layer Physical Layer

3. Figure 13.1 IEEE standard for LANs
In IEEE LLC deals with flow control, error control, and part of framing
MAC defines the specific access method for each LAN (e.g. CSMA/CD for Ethernet LANs and the token passing method for Token Ring and Token Bus.)
The LLC Provides one single data link control protocol for all IEEE LANs.
The MAC provides different protocols for different LANs.

4. Topics discussed in this section:
STANDARD ETHERNET
The original Ethernet was created in 1976 at Xerox’s Palo Alto Research Center (PARC). Since then, it has gone through four generations. We briefly discuss the Standard (or traditional) Ethernet in this section.
Topics discussed in this section:
MAC Sublayer Physical Layer

5. Figure 13.3 Ethernet evolution through four generations

6. Figure MAC frame

7. Figure 13.5 Minimum and maximum lengths
CRC - Cyclic Redundancy check for error detection information.
The Maximum length restriction has two reasons:
1 – memory was very expensive when Ethernet was designed.
2 – to prevent one station from monopolizing the shared medium.

8. Figure 13.6 Example of an Ethernet address in hexadecimal notation
Each station on Ethernet network has its own Network Interface Card (NIC), NIC fit inside the station and provide the station with a 6-byte physical address (it is the MAC Address).

9. Figure 13.8 Categories of Standard Ethernet
Four Physical layer implementations

10. Figure 13.10 10Base5 implementation
10Base5, also called thick Ethernet or Thicknet

11. Figure 13.11 10Base2 implementation
10Base2, thin Ethernet, or Cheapernet

12. Figure 13.12 10Base-T implementation
10Base-T, twisted-pair Ethernet

13. Figure 13.13 10Base-F implementation

14. Table 13.1 Summary of Standard Ethernet implementations

15. Topics discussed in this section:
CHANGES IN THE STANDARD
The 10-Mbps Standard Ethernet has gone through several changes before moving to the higher data rates. These changes actually opened the road to the evolution of the Ethernet to become compatible with other high-data-rate LANs.
Topics discussed in this section:
Bridged Ethernet Switched Ethernet Full-Duplex Ethernet

16. Figure 13.14 Sharing bandwidth
10 Mbps is shared among all stations, the stations share the bandwidth of the network.
If only one station has frames to send, it benefits from the total capacity (10 Mbps).
If two stations have a lot of frames to send, they probably alternate un usage, each station on average, sends at rate of 5 Mbps.

17. Figure 13.15 A network with and without a bridge
Bridge’s advantages:
1 – raising the bandwidth
2 – Separation of the Collision Domain

18. Figure 13.16 Collision domains in an unbridged network and a bridged network

19. Figure 13.17 Switched Ethernet
A Switch is a multiple-port bridge

20. Figure 13.18 Full-duplex switched Ethernet
10Base5 and 10Base2 have a limitation which is the communication is half-duplex.
So there is a need to move from switched Ethernet to Full-Duplex switched Ethernet.
Full-Duplex means increase the capacity of each domain from 10 to 20 Mbps.
In case of Full-Duplex there is no need for the CSMA/CD method. Each station has two links one for transmission and one for receiving.

21. Topics discussed in this section:
FAST ETHERNET
Fast Ethernet was designed to compete with LAN protocols such as FDDI or Fiber Channel. IEEE created Fast Ethernet under the name 802.3u. Fast Ethernet is backward-compatible with Standard Ethernet, but it can transmit data 10 times faster at a rate of 100 Mbps.
Topics discussed in this section:
MAC Sublayer Physical Layer

22. Figure 13.19 Fast Ethernet topology
No Bus topologies.

23. Figure 13.20 Fast Ethernet implementations

24. Table 13.2 Summary of Fast Ethernet implementations

25. Topics discussed in this section:
GIGABIT ETHERNET
The need for an even higher data rate resulted in the design of the Gigabit Ethernet protocol (1000 Mbps). The IEEE committee calls the standard 802.3z.
Topics discussed in this section:
MAC Sublayer Physical Layer
Ten-Gigabit Ethernet

26. Figure 13.22 Topologies of Gigabit Ethernet

27. Figure 13.23 Gigabit Ethernet implementations

28. Table 13.3 Summary of Gigabit Ethernet implementations

29. Table 13.4 Summary of Ten-Gigabit Ethernet implementations