1 / 14

Ethernet Frames

Ethernet Frames. Ethernet II frame format DIX IEEE 802.3 Frame Takes an 802.2 (LLC)frame. IEEE 802.3 Frames. Ethernet Frames. IEEE 802.2 Frame Logic link control – part HDLC functions Any logical addressing Control information Data encapsulation Common to all 802 MAC protocols.

elsa
Télécharger la présentation

Ethernet Frames

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ethernet Frames • Ethernet II frame format • DIX • IEEE 802.3 Frame • Takes an 802.2 (LLC)frame

  2. IEEE 802.3 Frames

  3. Ethernet Frames • IEEE 802.2 Frame • Logic link control – part HDLC functions • Any logical addressing • Control information • Data encapsulation • Common to all 802 MAC protocols

  4. Ethernet Frames • IEEE 802.2 Frame - LLC • DSAP – Destination Service Access Point • Identifies protocol stack on the receiving sys • 1 byte – 1st bit • 0- individual • 1 group

  5. Ethernet Frames • IEEE 802.2 Frame - LLC • SSAP – Source Service Access Point • Identifies protocol stack on the sending sys • 1 byte – 1st bit • 0- command • 1 - response

  6. Ethernet Frames • IEEE 802.2 Frame - LLC • Control field • I frame – information • S frame – supervisory • U frame – unnumbered frame

  7. 100Base standards • 802.3u task force – 100Mbps, same Ethernet MAC – use CAT5 • 802.12 - Demand Priority Access Method • Use CAT3 • Both accepted officially June 1995 • 802.3u popular – 100BaseT or Fast Ethernet

  8. 100 Base T • 10 Base T collision domain • 2500 mts at 10 Mbps • Collision sensing time = 512 bit period • Smallest frame size • 100 Base T – collision domain?

  9. 100 Base T • 100 Base T – features • No change in the frame format • No change in the access method – full duplex • Access rate changed • Collision domain changed • Data rate greater 10 times, collision decreased by 10 times

  10. 100 Base T – physical layer • Star topology • Two Specs • 100Base X – PCS – PMA – 2 cables • 100 Base T4 – • Four UTP cables – CAT3 – voice grade • To get reduced baud rate for a given bit rate 8B/6T encoding was used (10Base T used 4B/5B encoding)

  11. 10 Base T – > 100 Base T • 802.3u committee specifications • Seamless integration with installed base • Order of two times the 10BaseT cost (or less) • Increased aggregate bandwidth • Be standardized and supported by multiple vendors • Solution to time bound delivery

  12. 100 Base T • Auto – negotiation • Speed adjustment among devices • Allows negotiation on optimal mode between systems • Half duplex (csma/cd) • Full duplex • RS, MII, auto negotiation - Full duplex aware

  13. Flow control • Special MAC frame – PAUSE • Turn-off the transmitter • Suitable only on point-to-point links between transmitting and receiving stations • Pause ‘Time’ information sent • End of timer – transmitter can start sending

  14. PAUSE Frame • DA – globally unique – 01-80-c2-00-00-01 • Type field –88-08 • 2 byte timer field – in 512 bit times • Full duplex – derivative of switched Ethernet • Distance limitation due to collision domain removed

More Related