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Wired LANs and Ethernet

Wired LANs and Ethernet. Semester: 131 Course: CSET 221 Computer Networking Instructor: Farhan Khan Computer Science & Engineering Technology Unit Hafr Al-Batin Community College. Outline. IEEE standards for LAN/MAN/WAN Standard Ethernet Unicast and multicast addresses Fast Ethernet

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Wired LANs and Ethernet

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  1. Wired LANs and Ethernet Semester: 131 Course: CSET 221 Computer Networking Instructor: Farhan Khan Computer Science & Engineering Technology Unit Hafr Al-Batin Community College

  2. Outline • IEEE standards for LAN/MAN/WAN • Standard Ethernet • Unicast and multicast addresses • Fast Ethernet • Gigabit Ethernet • Ten-Gigabit Ethernet

  3. IEEE Standards • Project 802  standards for enabling intercommunication among equipment from a variety of manufacturers • E.g., • IEEE 802.3  Ethernet • IEEE 802.5  Token Ring • IEEE 802.11  Wireless LAN (Wi-Fi) • IEEE 802.15  Wireless PAN (Bluetooth, etc) • http://en.wikipedia.org/wiki/IEEE_802

  4. IEEE Standards for LANs

  5. Logical Link Control Sublayer • Provides flow and error control for upper layer protocols • Most upper layer protocols (such as IP) do not require such services DSAP – Destination ServiceAccess Point SSAP – Source ServiceAccess Point (Similar to TCP/IP ports)

  6. Wired Ethernet • "Traditional" or "Original" Ethernet created at Xerox's Palo Alto Research Center (PARC) in 1976 • Ethernet standards are set by IEEE 802.3 working group

  7. Evolution of Ethernet Ethernet Evolution Standard Ethernet(10 Mbps) Fast Ethernet(100 Mbps) Gigabit Ethernet Ten-Gigabit Ethernet 100-Gigabit Ethernet

  8. Standard Ethernet

  9. Standard Ethernet • Data link layer is divided into • logical link control (LLC) sublayer and • media access control (MAC) sublayer. • MAC Sublayer • Access Method: CSMA/CD • Frame contains destination and source physical address. • No acknowledgment procedure and thus known as unreliable.

  10. IEEE 802.3 MAC Frame • Preamble: Alternating 0s and 1s; used for synchronizing; 7bytes (56 bits). • Start Frame Delimiter (SFD): 10101011 indicates the start of the frame. Last two bits alerts that the next field is destination address. • Destination Address (DA): 6 bytes (48 bits) physical address of destination station(s) • Source Address (SA): 6 bytes (48 bits) physical address of sender • Length/Type: if less than 1500, it indicates the length of data field. If greater than 1536, it indicates the type of PDU. • Data: 46 to 1500 bytes; • CRC:CRC-32 for error detection

  11. IEEE 802.3 MAC Frame

  12. Min and Max Frame Length

  13. Frame length: Minimum: 64 bytes (512 bits) Maximum: 1518 bytes (12,144 bits)

  14. Ethernet Addresses • 48 bits (6 bytes) in length • Uniquely assigned to each Ethernet network interface card (NIC) • Usually written in hexadecimal notation • E.g.,

  15. Unicast vs. Multicast Addresses • A unicast address defines one recipient • A multicast address defines a group of recipients • The broadcast address defines a group of all stations in the same LAN • A special case of multicast addresses • All bits are 1s

  16. The least significant bit of the first byte defines the type of address.If the bit is 0, the address is unicast;otherwise, it is multicast.

  17. The broadcast destination address is a special case of the multicast address in which all bits are 1s.

  18. Example • Define the type of the following destination addresses: • 4A:30:10:21:10:1A • 47:20:1B:2E:08:EE • FF:FF:FF:FF:FF:FF

  19. Solution To find the type of the address, we need to look at the second hexadecimal digit from the left. If it is even, the address is unicast. If it is odd, the address is multicast. If all digits are F’s, the address is broadcast. Therefore, we have the following: a. This is a unicast address because A in binary is 1010. b. This is a multicast address because 7 in binary is 0111. c. This is a broadcast address because all digits are F’s.

  20. Ethernet Access Control • Also called contention-based access • No station is assigned to control another • Access Method is called CSMA/CD

  21. CSMA/CD • Carrier Sense Multiple Access with Collision Detection • In CSMA/CD, the station senses the carrier or channel before transmitting frame. • The station that places its data onto the channel after sensing the channel continues to sense the channel even after the data transmission. • If collision is detected, the station aborts its transmission and waits for predetermined amount of time & then sends its data again.

  22. CSMA/CD • Station continues to monitors channel after sending a frame

  23. CSMA/CD: Flow Diagram

  24. CSMA/CD: Flow Diagram Set the back off parameter to zero. • The station that has a ready frame senses the line. • If no one is transmitting, it sends the frame. • If there is no collision for a period corresponding to one complete frame, then the transmission is successful. • If there is a collision detected, the station sends the jam signal to inform the other stations about the collision. • The station then increments the backofftime and waits for a random backofftime and sends the frame again. • If the backoffhas reached its limit then the station aborts the transmission.

  25. Categories of Standard Ethernet

  26. Encoding in Standard Ethernet

  27. 10Base5 Implementation

  28. 10Base2 Implementation

  29. 10Base-T Implementation CAT3 Cable

  30. 10Base-F Implementation

  31. Standard Ethernet Summary

  32. Raising the Bandwidth

  33. Bridged Ethernet • A bridge divides a network into two or more segments • Each segment is independent of one another, bandwidth-wise

  34. Collision Domain • Bridges help split collision domain into smaller ones

  35. Switched Ethernet

  36. Full-Duplex Ethernet

  37. Fast Ethernet

  38. Fast Ethernet • Data rate: 100 Mbps • Standard  IEEE 802.3u • Backward-compatible with Standard Ethernet

  39. Fast Ethernet Topologies

  40. Fast Ethernet Implementations

  41. Encoding for 100Base-FX

  42. Encoding for 100Base-FX

  43. Encoding for 100Base-T4

  44. Fast Ethernet Summary

  45. Gigabit Ethernet

  46. Gigabit Ethernet • 1000 Mbps • Standard  IEEE 802.3z, 802.3ab

  47. Gigabit Ethernet Encoding

  48. 4D-PAM5 Encoding • Used in 1000Base-T

  49. Gigabit Ethernet Summary

  50. 10-Gigabit and Up • IEEE Standards • 802.3ae  10GbE over fiber • 802.3ak  10GbE over twin axial cable (10GBASE-CX4) • 802.3an  10GbE over UTP (10GBASE-T) • 802.3ba  40GbE and 100GbE

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