1. Ethernet Technologies
Module 7
Ethernet
Technologies

2. Legacy Ethernet
10BASE BASE BASE-T
Same Timing Parameters. . .

3. Legacy Ethernet
10BASE BASE BASE-T
Same Frame Format. . .

4. Legacy Ethernet Manchester Line Encoding 10BASE2 10BASE5 10BASE-T
Same Transmission Process. . .
Manchester
Line
Encoding

5. Legacy Ethernet 10BASE2 10BASE5 10BASE-T
Same Basic Design Rule or common architectural features. . .
5 segments connected on the network
4 repeaters
3 segments of the 5 segments can have stations connected. The other two segments must be inter-repeater link segments with no stations connected.

6. 10BASE5 & 10BASE2 10BASE5 10BASE2 Thick Coax cable Thin Coax cable
Inexpensive
No configuration
500 m segment length
Half-duplex mode
10BASE2
Thin Coax cable
185 m segment length
Half-duplex mode

7. 10BASE-T Cheaper & easier to install Used Category 3 UTP at first
Can also use Category 5 or 5e UTP
RJ-45 connectors
Star or extended star topology
Shared bus device (hub)
Transmit pair on the receiving side are connected to the receiving pair
Half (10 Mbps) or Full (20 Mbps) Duplex
100 m segment length

8. Fast Ethernet
100BASE-TX
100BASE-FX
Copper UTP
Multimode optical fiber

9. Fast Ethernet 100BASE-TX 100BASE-FX Timing parameters are the same
Frame format is the same
2 separate encoding steps
4B/5B
2nd part specific to the media (copper or fiber)

10. 4Bit/5Bit Encoding
4B/5B encoding is sometimes called 'Block coding'. Each 4-bit 'nibble' of received data has an extra 5th bit added. If input data is dealt with in 4-bit nibbles there are 24 = 16 different bit patterns. With 5-bit 'packets' there are 25 = 32 different bit patterns. This enables clock synchronizations required for reliable data transfer.

11. Fast Ethernet 100BASE-TX 100BASE-FX
Could be used for backbone applications, connections between floors and buildings where copper is less desirable (inter-building backbone), and also in high noise environments.
Never really accepted because Gigabit Ethernet came into the picture
First designed for inter-building backbone connectivity
Two separate transmit-receive paths
Full-duplex or half-duplex

12. Class I Repeater
Can use between media segments with different signaling techniques (100BASE-TX to 100BASE-FX)
Only 1 Class I Repeater to be used per collision domain

13. Class II Repeater
Used between segment types that use the same signaling techniques (100BASE-TX to 100BASE-TX)
May only use 2 with maximum cable lengths
Cannot mix 2 different segments (100BASE-TX to 100BASE-FX)

14. Gigabit Ethernet (1000BASE-X) (1000 Mbps or 1 Gbps)
General infrastructure needs
High-speed cross-connects
Backbone installations
IEEE 802.3z specifies 1Gbps full duplex over optical fiber
More complex encoding needed because of the timing

15. Gigabit Ethernet Gave more speed for intra-building backbones
Inter-switch links
Must be interoperable with 10BASE-T and 100BASE-TX
All 4 pairs of wires used at the same time, full-duplex
Transmission and reception of data happens in both directions on the same wire at the same time
All versions of Gigabit Ethernet share the same timing, frame format, and transmission

16. 1000BASE-X Short wavelength Long wavelength 1000BASE-SX 1000BASE-LX
Uses NRZ line encoding
the determination of whether a bit is a zero or a one is made by the level of the signal rather than when the signal changes levels.
The NRZ signals are then pulsed into the fiber using either short-wavelength or long-wavelength light sources
Short wavelength
1000BASE-SX
Long wavelength
1000BASE-LX

17. 10 Gigabit (GbE) Ethernet
10 Gbps full duplex over fiber only (802.3ae)
Frame format is same as all Ethernet
CMSA/CD no longer a consideration

18. 10 Gigabit (GbE) Ethernet
Each data bit duration is now 0.1 nanoseconds (1,000 GbE data bits in the same bit time as one data bit in a 10-Mbps Ethernet data stream)
Uses 2 separate encoding steps
10GBASE-LX4 uses Wide Wavelength Division Multiplex (WWDM) to multiplex four bit simultaneous bit streams as four wavelengths of light launched into the fiber at one time.
Further info
No repeater rules defined since half-duplex is not supported

19. Wide Wavelength Division Multiplexing
Wide wavelengths are diffracted into a fiber and then diffracted out the other end
When the light propagation is reversed, the multiplexer becomes the demultiplexer.

20. Development of fiber based Ethernet
Mostly limited by :
The actual electronics technology itself:
Emitters
Detectors
And:
The manufacturing process itself

21. Data Encapsulation Process
To prepare for Lab 7.1.2

22. Data Encapsulation Process
Application Layer
FTP (File Transfer Protocol) client PC sending a text document to an FTP server PC
Presentation Layer
Text is coded in ASCII (American Standard Code for Information Interchange)
Session Layer
Coordinates dialog between the two PCs

23. Data Encapsulation Process
Transport Layer
Segments the data stream from upper layers
Builds a virtual circuit between the two PCs
FTP is handled by TCP (Transmission Control Protocol) at this layer
TCP tracks the conversation using destination and source port numbers
FTP server ports are 20 for Data and 21 for Control
FTP client port is dynamically set by client PC using IANA (Internet Assigned Numbers Authority) specified range of to 65535; each communication session referenced by a different port

24. Data Encapsulation Process
Network Layer
Places TCP segments into IP (Internet Protocol) packets
Enables end-to-end routing from the source network, over intermediate networks, to the destination network
IP identifies TCP as its payload by placing a “6” in its protocol field

25. Data Encapsulation Process
Data Link Layer
Prepares IP packet for transmission on its directly attached network, in this case an Ethernet LAN
The IP packet is placed in an Ethernet frame which accesses the network using Ethernet’s CSMA/CD protocol
The frame identifies its payload as IPv4 by placing a value of “0x0800” in its type field
As the MAC sublayer transfers each individual octet of the frame to the Physical Layer, it reorders all but the FCS for encoding least-significant bit first

26. Data Encapsulation Process
Physical Layer
Encodes the Ethernet frame onto the physical medium
Ethernet utilizes Manchester encoding scheme
Binary value is determined by the direction of the edge transition in the middle of the timing window
Ones are represented by a rise in voltage (copper medium) or power level (fiber medium)
Zeroes are represented by a drop in voltage or power level

27. Data Encapsulation Process
Data Link Layer / Physical Layer
Framing and encoding is changed at each router hop as appropriate to the Layer 2 / Layer 1 protocols in use by the next network along the path to the destination

28. Ethernet Frame Preamble (7 bytes)
Establish and maintain clock synchronization; although faster versions are synchronous, Ethernet is asynchronous
Avoid baseline wander
Hexadecimal “ ”
Binary “ … ”

29. Ethernet Frame Start of Frame Delimiter (1 byte) Hexadecimal “D5”
Binary “ ”
When reordered for Physical Layer encoding, it reads “ ”
The two consecutive one’s mark the boundary between the Preamble and the frame’s Destination Address

30. Ethernet Frame Destination Address (6 bytes)
MAC (Media Access Control) address of destination computer
The destination exists on the same LAN as the source computer
It may belong to the LAN’s router if the packet’s destination is on another network
48 bits in length, written as 12 hexadecimal digits
First 6 hexadecimal digits represent the OUI (Organizational Unique Identifier) for the equipment manufacturer; the IEEE administers OUI assignments
Last 6 hexadecimal digits indicate the serial number assigned by the manufacturer

31. Ethernet Frame Source Address (6 bytes)
MAC (Media Access Control) address of source computer
The source exists on the same LAN as the destination computer
It may belongs to the LAN’s router if the packet’s source is on another network
48 bits in length, written as 12 hexadecimal digits
First 6 hexadecimal digits represent the OUI (Organizational Unique Identifier) for the equipment manufacturer; the IEEE administers OUI assignments
Last 6 hexadecimal digits indicate the serial number assigned by the equipment manufacturer

32. Ethernet Frame Length/Type (2 bytes)
Early IEEE versions of Ethernet used this field to indicate the number of bytes in the data field
Later IEEE versions of Ethernet allow this field to indicate either the length of the data field or the Layer 3 protocol type being transported
This allows compatibility between IEEE and Ethernet version 2 developed by DIX (DEC, Intel, Xerox)
A hexadecimal value < “0600” (decimal 1536) indicates length, while >= “0600” indicates an Ethernet II type code
A hexadecimal value of “0800” indicates the frame is carrying an IPv4 packet

33. Ethernet Frame Data / Padding (46 to 1500 bytes)
The Network Layer packet
Less than 46 bytes will result in an Ethernet “runt” which could lead to an undetected collision
Greater than 1500 bytes will result in an Ethernet “giant” which exceeds maximum frame length
For frames with a length/type < 0x0600, this field includes the LLC (Logical Link Control) sublayer header to indicate the packet’s Layer 3 protocol

34. Ethernet Frame Frame Check Sequence (4 bytes)
Used to ensure frames received without errors
Consists of a CRC (Cyclic Redundancy Check) ran against the Destination Address, Source Address, Length/Type and Data fields
Calculated by the source, value attached to frame
Calculated by the recipient and compared to source’s calculation (= good / != bad)

35. Lab 7.1.2 Decoding an Ethernet Waveform
Locate Start of Frame Delimiter (SFD)
Immediately following the Preamble, there should be a binary sequence of “ ”
This sequence is the SFD
The Destination Address follows immediately after the “11”

36. Lab 7.1.2 Decoding an Ethernet Waveform
Group binary values into octets starting with SFD
Place a marker around each binary octet working backward and forward from the SFD
Grouping each octet simplifies the next step in which you reorder the octet binaries from their Layer 1 “least-significant bit first” orderings into their Layer 2 “most-significant bit first” orderings

37. Lab 7.1.2 Decoding an Ethernet Waveform
Reorder octets into Layer 2 sequence
Write down the reverse bit order of each octet
This new ordering provides the actual Layer 2 frame

38. Lab 7.1.2 Decoding an Ethernet Waveform
Convert octets into hexadecimal digits
Each octet is represented by two hexadecimal digits
For example, the Preamble’s Layer 2 binary pattern of “ ” is represented by the hex value “55”

39. Lab 7.1.2 Decoding an Ethernet Waveform
Use hex values to identify destination and source Organizational Unique Identifier (OUI), length/type, and initial portion of IP header
For the public OUI listing, reference
For the EtherTypes listing, reference the RFC Index at
Enter a search for “Assigned Numbers”
Locate the latest version of document
Search the document for “EtherTypes”
For the IP header format, reference RFC 791 page 10

40. Ethernet Technologies
Module 7
Ethernet
Technologies