1 Version 3.0 Module 7 Ethernet Technologies

2 Version 3.0 Legacy Ethernet 10BASE2 10BASE5 10BASE-T Same Timing Parameters...

3 Version 3.0 Legacy Ethernet 10BASE2 10BASE5 10BASE-T Same Frame Format...

4 Version 3.0 Legacy Ethernet 10BASE2 10BASE5 10BASE-T Same Transmission Process... Manchester Line Encoding

5 Version 3.0 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 Version BASE5 & 10BASE2 10BASE5 Thick Coax cable Inexpensive No configuration 500 m segment length Half-duplex mode 10BASE2 Thin Coax cable 185 m segment length Half-duplex mode

7 Version BASE-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 Version 3.0 Fast Ethernet 100BASE-TX 100BASE-FX Copper UTP Multimode optical fiber

9 Version 3.0 Fast Ethernet 100BASE-TX 100BASE-FX Timing parameters are the same Frame format is the same 2 separate encoding steps –4B/5B –2 nd part specific to the media (copper or fiber)

10 Version 3.0 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 2 4 = 16 different bit patterns. With 5-bit 'packets' there are 2 5 = 32 different bit patterns. This enables clock synchronizations required for reliable data transfer. 4Bit/5Bit Encoding

11 Version 3.0 Fast Ethernet 100BASE-TX 100BASE-FX Two separate transmit-receive paths Full-duplex or half- duplex 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

12 Version 3.0 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 Version 3.0 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 Version 3.0 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 Version 3.0 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 Version BASE-X 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 Version 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 Version 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.Wide Wavelength Division Multiplex (WWDM) Further info No repeater rules defined since half-duplex is not supported

19 Version 3.0 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 Version 3.0 Development of fiber based Ethernet Mostly limited by : –The actual electronics technology itself: Emitters Detectors –And: The manufacturing process itself

21 Version 3.0 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

22 Version 3.0 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

23 Version 3.0 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

24 Version 3.0 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

25 Version 3.0 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

26 Version 3.0 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

27 Version 3.0 Ethernet Frame Preamble (7 bytes) –Establish and maintain clock synchronization; although faster versions are synchronous, Ethernet is asynchronous –Avoid baseline wander –Hexadecimal “ ” –Binary “ … ”

28 Version 3.0 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

29 Version 3.0 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

30 Version 3.0 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

31 Version 3.0 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” indicates an Ethernet II type code –A hexadecimal value of “0800” indicates the frame is carrying an IPv4 packet

32 Version 3.0 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

33 Version 3.0 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)

34 Version 3.0 Module 7 Ethernet Technologies