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Ethernet

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Parthipan Parthi
Parthipan Parthi
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V.Parthipan assistant Professor ,Saveetha University ,chennai India
DDeevveellooppeedd dduurriinngg tthhee mmiidd--11997700 aatt XXeerrooxx PPaalloo AAllttoo RReesseeaarrcchh CCeenntteerr ((BBoobb MMeettccaallffee)) LLaatteerr rreeffiinneemmeenntt bbyy DDEECC,, IInntteell aanndd XXeerrooxx ((DDIIXX ssttaannddaarrdd)) BBeeccaammee IIEEEEEE 880022..33 iinn 11998855 DDiiffffeerreenntt ffrraammee ffoorrmmaatt bbeettwweeeenn EEtthheerrnneett aanndd IIEEEEEE 880022..33
Data link layer Physical layer NNIICC AAUUII ccaabbllee ttrraannsscceeiivveerr 00..55 ??CCooaaxx ttaapp BBNNCC ccoonnnneeccttoorr station interface data encapsulation link management encoding and decoding transmission and receipt
hhuubb 1100BBaassee22 -- TThhiinn EEtthheerrnneett 1100BBaassee55 -- TThhiicckk EEtthheerrnneett rroouutteerr 1100BBaasseeTT--TTwwiisstteedd ppaaiirr sseerrvveerr hhuubb bbrriiddggee
VVaarriioouuss ssttaannddaarrdd ddeeffiinneedd ffoorr IIEEEEEE880022..33 wwiitthh aa ccoonncciissee nnoottaattiioonn 1100BBaassee55 ---- tthhiicckkwwiirree ccooaaxxiiaall 1100BBaassee22 ---- tthhiinnwwiirree ccooaaxxiiaall oorr cchheeaappeerrnneett 1100BBaasseeTT ---- ttwwiisstteedd ppaaiirr 1100BBaasseeFF ---- ffiibbeerr ooppttiiccss 1100BBrrooaadd3366 ---- bbrrooaaddbbaanndd FFaasstt EEtthheerrnneett 110000BBaasseeTTXX,, 110000BBaasseeTT44,, 110000BBaasseeFF aanndd 110000 VVGG--AAnnyyLLAANN ddaattaa rraattee iinn MMbbppss ssiiggnnaalliinngg bbaasseebbaanndd oorr bbrrooaaddbbaanndd mmaaxxiimmuumm sseeggmmeenntt lleennggtthh iinn hhuunnddrreeddss ooff mmeetteerrss 10 Base 5
ttaapp :: ccaabbllee ddooeess nnoott ttoo bbee ccuutt ttrraannsscceeiivveerr :: sseenndd//rreecceeiivvee,, ccoolllliissoonn ddeetteeccttiioonn,, eelleeccttrroonniiccss iissoollaattiioonn AAUUII :: AAttttaacchhmmeenntt UUnniitt IInntteerrffaaccee UUssee ffoorr bbaacckkbboonnee nneettwwoorrkkss 00..55??CCooaaxx vvaammppiirree ttaapp BBNNCC ccoonnnneeccttoorr ttrraannsscceeiivveerr AAUUII ccaabbllee NNIICC mmaaxxiimmuumm sseeggmmeenntt lleennggtthh==550000mm mmaaxxiimmuumm nnuummbbeerr ooff ssttaattiioonnss ppeerr sseeggmmeenntt==110000 mmiinniimmuumm ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 22..55 mm mmaaxxiimmuumm nneettwwoorrkk ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 22..88kkmm
00..2255 ??CCooaaxx BBNNCC TT--ccoonnnneeccttoorr NNIICC BBNNCC ccoonnnneeccttoorr NNoo ddrroopp ccaabbllee uussee ffoorr ooffffiiccee LLAANN mmaaxxiimmuumm sseeggmmeenntt lleennggtthh==118855mm mmaaxxiimmuumm nnuummbbeerr ooff ssttaattiioonnss ppeerr sseeggmmeenntt==3300 mmiinniimmuumm ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 00..55 mm mmaaxxiimmuumm nneettwwoorrkk ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 992255 mm
NNIICC AA hhuubb ffuunnccttiioonnss aass aa rreeppeeaatteerr uussee ffoorr ooffffiiccee LLAANN hhuubb mmaaxxiimmuumm sseeggmmeenntt lleennggtthh == 110000mm
10BaseF specification eennaabbllee lloonngg ddiissttaannccee ccoonnnneeccttiioonnss wwiitthh tthhee uussee ooff ooppttiiccaall ffiibbeerr.. TThhrreeee ssttaannddaarrddss aarree:: 1100BBaasseeFFPP -- AA ppaassssiivvee--ssttaarr ttooppoollooggyy,, uupp ttoo 11 kkmm lliinnkk 1100BBaasseeFFLL -- AAnn aassyynncchhrroonnoouuss ppooiinntt--ttoo--ppooiinntt lliinnkk ((aa nneeww FFOOIIRRLL)) ,, uupp ttoo 22 kkmm lliinnkk 1100BBaasseeFFBB -- AA ssyynncchhoonnoouuss ppooiinntt--ttoo--ppooiinntt lliinnkk ,, uupp ttoo 22 kkmm lliinnkk wwiitthh 1155 ccaassccaaddee rreeppeeaatteerrss
SSttaattiioonn lliisstteennss ttoo tthhee mmeeddiiuumm bbeeffoorree ttrraannssmmiittttiinngg ((lliisstteenn bbeeffoorree ttaallkkiinngg ;;LLBBTT)) NNoonn ppeerrssiisstteenntt CCSSMMAA iiff mmeeddiiuumm iiss iiddllee,, ttrraannssmmiitt iiff mmeeddiiuumm bbuussyy,, wwaaiittss aa rraannddoomm ppeerriiooddss aann tthheenn rreesseennssee mmeeddiiuumm 11--ppeerrssiisstteenntt CCSSMMAA iiff mmeeddiiuumm iiss iiddllee,, ttrraannssmmiitt iiff mmeeddiiuumm bbuussyy,, ccoonnttiinnuuee ttoo lliisstteenn uunnttiill tthhee cchhaannnneell iiss sseennsseedd iiddllee;; tthheenn ttrraannssmmiitt iimmmmeeddiiaatteellyy
More than ttwwoo ssttaattiioonn sseenndd ffrraammee aatt tthhee ssaammee ttiimmee SSttaattiioonn ttrraannssmmiittss iittss ddaattaa wwhhiillee cchheecckkiinngg tthhee ccaahhaannnneell ffoorr ccoolllliissiioonn IIff aavveerraaggee DDCC vvoollttaaggee lleevveell eexxeeeeddss tthhee CCDD tthhrreesshhoolldd,, ccoolllliissiioonn iiss ddeetteecctteedd
HHooww ttoo ddeetteecctt SSttaattiioonn sseenndd ffrraammee aanndd sseennssee tthhee mmeeddiiuumm CCoolllliissiioonn ddeetteecctteedd iiff ssttaattiioonn sseennssee tthhee eexxeeeeddeedd ssiiggnnaall ssttrreennggtthh ((ccooaaxx)) tthheerree iiss ssiiggnnaall oonn mmoorree tthhaann oonnee iinnuutt ((UUTTPP)) HHooww ttoo ddoo TTrraannssmmiittttiinngg nnooddeess sseenndd aa jjaammmmiinngg ssiiggnnaall aafftteerr aa ccoolllliissiioonn iiss ddeetteecctteedd.. jjaamm
IIEEEEEE 880022..33 77 11 6 6 22 446--11550000 44 PA SFD DA SA LEN LLC PDU Pad FCS ccaallccuullaattiioonn ooff tthhee FFCCSS 644--11551188 bbyytteess 88 6 6 22 446--11550000 44 PA DA SA Type Data Pad FCS EEtthheerrnneett PPAA :: PPrreeaammbbllee -- 1100110011001100ss ffoorr ssyynncchhrroonniizzaattiioonn SSFFDD :: SSttaarrtt ooff FFrraammee ddeelliimmiitteerr ---- 1100110011001111 ttoo ssttaarrtt ffrraammee DDAA:: DDeessttiinnaattiioonn AAddddrreessss ---- MMAACC aaddddrreessss SSAA:: SSoouurrccee AAddddrreessss ---- MMAACC aaddddrreessss LLEENN:: LLeennggtthh ---- NNuummbbeerr ooff ddaattaa bbyytteess TTyyppee:: iiddeennttiiffyy tthhee hhiigghheerr --lleevveell pprroottooccooll LLLLCC PPDDUU++ppaadd ---- mmiinniimmuumm 446 bbyytteess,, mmaaxxiimmuumm 11550000 FFCCSS :: FFrraammee CChheecckk SSeeqquueennccee ---- CCRRCC--3322
1 1 46 I/G U/L 46-bit address 1 15 I/G 15-bit address TTwwoo aaddddrreessssffoorrmmaatt:: 4488 bbiittss 116 bbiittss I/GG =00 IInnddiivviidduuaall aaddddrreessss II//GG =11 GGrroouupp aaddddrreessss UU//LL=00 GGlloobbaall aaddmmiinniisstteerreedd aaddddrreessss UU//LL=11 LLooccaall aaddmmiinniisstteerreedd aaddddrreessss UUnniiccaasstt :: ddeeffiinnee aa ssiinnggllee ddeessttiinnaattiioonn BBrrooaaddccaasstt :: FFFFFFFFFFFFFFFF eeaacchh ssttaattiioonn oonn tthhee nneettwwoorrkk rreecceeiivvee aanndd aacccceepptt ffrraammeess mmuullttiiccaasstt :: aa ggrroouupp aaddddrreessss ddeeffiinneess mmuullttiippllee rreecceeppiieenntt
PA DA SA Type Data Pad FCS PA IInntteerrffrraammee ggaapp >> 99..6 mss Obligatory 9.6ms interval bbeettwweeeenn tthhee eemmiitttteedd ffrraammee aanndd tthhee nneeww oonnee TToo eennaabbllee ootthheerr ssttaattiioonnss wwiisshhiinngg ttoo ttrraannssmmiitt ttoo ttaakkee oovveerr aatt tthhiiss ttiimmee
Assemble frame carrier sense signal ON ? N Wait interframe gap time Start trnasmission collision detected? N Y Y send jam sequence Increment attempt. Y Compute backoff attempt limited? N Discard frame and wait backoff time transmission done? tranmit OK N Y
done receiving? Y Y Pass frame to next layer N N Discard frame Y N start receiving Matched DA FCS and frame size OK?
delay= 2 send frame collision detected? Y Y Discard frame random wait between 0 and delay-1 double delay limited delay<1024 N max delay is limited at 1023*51.2 ms=52.4 ms >16 attempts transmission done? tranmit OK N Y N 1st wait 0 or 1 slot time 2nd wait 0,1,2 or 3 slot time 3rd wait 0,1,2,..7 slot time kth wait 0.. 2k slot time after 10th collisions the interval is frozen at 1023 slots after 16th collisions , frame is discarded and report failure back to the upper layer
A and B locates at tthhee ffaarr eenndd ooff tthhee ccaabbllee (1) packet starts at time 0 (2) packet almost at B at t-d (3) B send packet; collision occurs at t (4) jam signal gets back to A at 2t A A A A B B B B A frame must take more than 2t to send to prevent the situation that the sender incorrect conclude that the frame was successfully sent. This slot times is = 51.2 ms corresponds to 512 bit = 64 bytes The minimum frame length is 64 bytes (excluding preamble) This answers why data field must have 46 bytes minimum

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Ethernet

  • 1. V.Parthipan assistant Professor ,Saveetha University ,chennai India
  • 2. DDeevveellooppeedd dduurriinngg tthhee mmiidd--11997700 aatt XXeerrooxx PPaalloo AAllttoo RReesseeaarrcchh CCeenntteerr ((BBoobb MMeettccaallffee)) LLaatteerr rreeffiinneemmeenntt bbyy DDEECC,, IInntteell aanndd XXeerrooxx ((DDIIXX ssttaannddaarrdd)) BBeeccaammee IIEEEEEE 880022..33 iinn 11998855 DDiiffffeerreenntt ffrraammee ffoorrmmaatt bbeettwweeeenn EEtthheerrnneett aanndd IIEEEEEE 880022..33
  • 3. Data link layer Physical layer NNIICC AAUUII ccaabbllee ttrraannsscceeiivveerr 00..55 ??CCooaaxx ttaapp BBNNCC ccoonnnneeccttoorr station interface data encapsulation link management encoding and decoding transmission and receipt
  • 4. hhuubb 1100BBaassee22 -- TThhiinn EEtthheerrnneett 1100BBaassee55 -- TThhiicckk EEtthheerrnneett rroouutteerr 1100BBaasseeTT--TTwwiisstteedd ppaaiirr sseerrvveerr hhuubb bbrriiddggee
  • 5. VVaarriioouuss ssttaannddaarrdd ddeeffiinneedd ffoorr IIEEEEEE880022..33 wwiitthh aa ccoonncciissee nnoottaattiioonn 1100BBaassee55 ---- tthhiicckkwwiirree ccooaaxxiiaall 1100BBaassee22 ---- tthhiinnwwiirree ccooaaxxiiaall oorr cchheeaappeerrnneett 1100BBaasseeTT ---- ttwwiisstteedd ppaaiirr 1100BBaasseeFF ---- ffiibbeerr ooppttiiccss 1100BBrrooaadd3366 ---- bbrrooaaddbbaanndd FFaasstt EEtthheerrnneett 110000BBaasseeTTXX,, 110000BBaasseeTT44,, 110000BBaasseeFF aanndd 110000 VVGG--AAnnyyLLAANN ddaattaa rraattee iinn MMbbppss ssiiggnnaalliinngg bbaasseebbaanndd oorr bbrrooaaddbbaanndd mmaaxxiimmuumm sseeggmmeenntt lleennggtthh iinn hhuunnddrreeddss ooff mmeetteerrss 10 Base 5
  • 6. ttaapp :: ccaabbllee ddooeess nnoott ttoo bbee ccuutt ttrraannsscceeiivveerr :: sseenndd//rreecceeiivvee,, ccoolllliissoonn ddeetteeccttiioonn,, eelleeccttrroonniiccss iissoollaattiioonn AAUUII :: AAttttaacchhmmeenntt UUnniitt IInntteerrffaaccee UUssee ffoorr bbaacckkbboonnee nneettwwoorrkkss 00..55??CCooaaxx vvaammppiirree ttaapp BBNNCC ccoonnnneeccttoorr ttrraannsscceeiivveerr AAUUII ccaabbllee NNIICC mmaaxxiimmuumm sseeggmmeenntt lleennggtthh==550000mm mmaaxxiimmuumm nnuummbbeerr ooff ssttaattiioonnss ppeerr sseeggmmeenntt==110000 mmiinniimmuumm ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 22..55 mm mmaaxxiimmuumm nneettwwoorrkk ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 22..88kkmm
  • 7. 00..2255 ??CCooaaxx BBNNCC TT--ccoonnnneeccttoorr NNIICC BBNNCC ccoonnnneeccttoorr NNoo ddrroopp ccaabbllee uussee ffoorr ooffffiiccee LLAANN mmaaxxiimmuumm sseeggmmeenntt lleennggtthh==118855mm mmaaxxiimmuumm nnuummbbeerr ooff ssttaattiioonnss ppeerr sseeggmmeenntt==3300 mmiinniimmuumm ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 00..55 mm mmaaxxiimmuumm nneettwwoorrkk ddiissttaannccee bbeettwweeeenn ttwwoo ssttaattiioonnss == 992255 mm
  • 8. NNIICC AA hhuubb ffuunnccttiioonnss aass aa rreeppeeaatteerr uussee ffoorr ooffffiiccee LLAANN hhuubb mmaaxxiimmuumm sseeggmmeenntt lleennggtthh == 110000mm
  • 9. 10BaseF specification eennaabbllee lloonngg ddiissttaannccee ccoonnnneeccttiioonnss wwiitthh tthhee uussee ooff ooppttiiccaall ffiibbeerr.. TThhrreeee ssttaannddaarrddss aarree:: 1100BBaasseeFFPP -- AA ppaassssiivvee--ssttaarr ttooppoollooggyy,, uupp ttoo 11 kkmm lliinnkk 1100BBaasseeFFLL -- AAnn aassyynncchhrroonnoouuss ppooiinntt--ttoo--ppooiinntt lliinnkk ((aa nneeww FFOOIIRRLL)) ,, uupp ttoo 22 kkmm lliinnkk 1100BBaasseeFFBB -- AA ssyynncchhoonnoouuss ppooiinntt--ttoo--ppooiinntt lliinnkk ,, uupp ttoo 22 kkmm lliinnkk wwiitthh 1155 ccaassccaaddee rreeppeeaatteerrss
  • 10. SSttaattiioonn lliisstteennss ttoo tthhee mmeeddiiuumm bbeeffoorree ttrraannssmmiittttiinngg ((lliisstteenn bbeeffoorree ttaallkkiinngg ;;LLBBTT)) NNoonn ppeerrssiisstteenntt CCSSMMAA iiff mmeeddiiuumm iiss iiddllee,, ttrraannssmmiitt iiff mmeeddiiuumm bbuussyy,, wwaaiittss aa rraannddoomm ppeerriiooddss aann tthheenn rreesseennssee mmeeddiiuumm 11--ppeerrssiisstteenntt CCSSMMAA iiff mmeeddiiuumm iiss iiddllee,, ttrraannssmmiitt iiff mmeeddiiuumm bbuussyy,, ccoonnttiinnuuee ttoo lliisstteenn uunnttiill tthhee cchhaannnneell iiss sseennsseedd iiddllee;; tthheenn ttrraannssmmiitt iimmmmeeddiiaatteellyy
  • 11. More than ttwwoo ssttaattiioonn sseenndd ffrraammee aatt tthhee ssaammee ttiimmee SSttaattiioonn ttrraannssmmiittss iittss ddaattaa wwhhiillee cchheecckkiinngg tthhee ccaahhaannnneell ffoorr ccoolllliissiioonn IIff aavveerraaggee DDCC vvoollttaaggee lleevveell eexxeeeeddss tthhee CCDD tthhrreesshhoolldd,, ccoolllliissiioonn iiss ddeetteecctteedd
  • 12. HHooww ttoo ddeetteecctt SSttaattiioonn sseenndd ffrraammee aanndd sseennssee tthhee mmeeddiiuumm CCoolllliissiioonn ddeetteecctteedd iiff ssttaattiioonn sseennssee tthhee eexxeeeeddeedd ssiiggnnaall ssttrreennggtthh ((ccooaaxx)) tthheerree iiss ssiiggnnaall oonn mmoorree tthhaann oonnee iinnuutt ((UUTTPP)) HHooww ttoo ddoo TTrraannssmmiittttiinngg nnooddeess sseenndd aa jjaammmmiinngg ssiiggnnaall aafftteerr aa ccoolllliissiioonn iiss ddeetteecctteedd.. jjaamm
  • 13. IIEEEEEE 880022..33 77 11 6 6 22 446--11550000 44 PA SFD DA SA LEN LLC PDU Pad FCS ccaallccuullaattiioonn ooff tthhee FFCCSS 644--11551188 bbyytteess 88 6 6 22 446--11550000 44 PA DA SA Type Data Pad FCS EEtthheerrnneett PPAA :: PPrreeaammbbllee -- 1100110011001100ss ffoorr ssyynncchhrroonniizzaattiioonn SSFFDD :: SSttaarrtt ooff FFrraammee ddeelliimmiitteerr ---- 1100110011001111 ttoo ssttaarrtt ffrraammee DDAA:: DDeessttiinnaattiioonn AAddddrreessss ---- MMAACC aaddddrreessss SSAA:: SSoouurrccee AAddddrreessss ---- MMAACC aaddddrreessss LLEENN:: LLeennggtthh ---- NNuummbbeerr ooff ddaattaa bbyytteess TTyyppee:: iiddeennttiiffyy tthhee hhiigghheerr --lleevveell pprroottooccooll LLLLCC PPDDUU++ppaadd ---- mmiinniimmuumm 446 bbyytteess,, mmaaxxiimmuumm 11550000 FFCCSS :: FFrraammee CChheecckk SSeeqquueennccee ---- CCRRCC--3322
  • 14. 1 1 46 I/G U/L 46-bit address 1 15 I/G 15-bit address TTwwoo aaddddrreessssffoorrmmaatt:: 4488 bbiittss 116 bbiittss I/GG =00 IInnddiivviidduuaall aaddddrreessss II//GG =11 GGrroouupp aaddddrreessss UU//LL=00 GGlloobbaall aaddmmiinniisstteerreedd aaddddrreessss UU//LL=11 LLooccaall aaddmmiinniisstteerreedd aaddddrreessss UUnniiccaasstt :: ddeeffiinnee aa ssiinnggllee ddeessttiinnaattiioonn BBrrooaaddccaasstt :: FFFFFFFFFFFFFFFF eeaacchh ssttaattiioonn oonn tthhee nneettwwoorrkk rreecceeiivvee aanndd aacccceepptt ffrraammeess mmuullttiiccaasstt :: aa ggrroouupp aaddddrreessss ddeeffiinneess mmuullttiippllee rreecceeppiieenntt
  • 15. PA DA SA Type Data Pad FCS PA IInntteerrffrraammee ggaapp >> 99..6 mss Obligatory 9.6ms interval bbeettwweeeenn tthhee eemmiitttteedd ffrraammee aanndd tthhee nneeww oonnee TToo eennaabbllee ootthheerr ssttaattiioonnss wwiisshhiinngg ttoo ttrraannssmmiitt ttoo ttaakkee oovveerr aatt tthhiiss ttiimmee
  • 16. Assemble frame carrier sense signal ON ? N Wait interframe gap time Start trnasmission collision detected? N Y Y send jam sequence Increment attempt. Y Compute backoff attempt limited? N Discard frame and wait backoff time transmission done? tranmit OK N Y
  • 17. done receiving? Y Y Pass frame to next layer N N Discard frame Y N start receiving Matched DA FCS and frame size OK?
  • 18. delay= 2 send frame collision detected? Y Y Discard frame random wait between 0 and delay-1 double delay limited delay<1024 N max delay is limited at 1023*51.2 ms=52.4 ms >16 attempts transmission done? tranmit OK N Y N 1st wait 0 or 1 slot time 2nd wait 0,1,2 or 3 slot time 3rd wait 0,1,2,..7 slot time kth wait 0.. 2k slot time after 10th collisions the interval is frozen at 1023 slots after 16th collisions , frame is discarded and report failure back to the upper layer
  • 19. A and B locates at tthhee ffaarr eenndd ooff tthhee ccaabbllee (1) packet starts at time 0 (2) packet almost at B at t-d (3) B send packet; collision occurs at t (4) jam signal gets back to A at 2t A A A A B B B B A frame must take more than 2t to send to prevent the situation that the sender incorrect conclude that the frame was successfully sent. This slot times is = 51.2 ms corresponds to 512 bit = 64 bytes The minimum frame length is 64 bytes (excluding preamble) This answers why data field must have 46 bytes minimum

Editor's Notes

  • #3: Xerox performed initial development of Ethernet and was joined by the Digital Equipment Corporation (Digital) and Intel to define the Ethernet 1 specification in 1980. The same group subsequently released the Ethernet 2 specification in 1984. The Ethernet specification describes a CSMA/CD LAN. The IEEE 802.3 subcommittee adopted Ethernet as its model for its CSMA/CD LAN specification. As a result, Ethernet 2 and IEEE 802.3 are identical in the way they use the physical medium. However, the two specifications differ in their descriptions of the data link layer. These differences do not prohibit manufacturers from developing network interface cards that support the common physical layer, and software that recognizes the differences between the two data links.
  • #4: The IEEE 802.3 10Base5 supports 10 Mbps basband transmission. The standard specifies the 0.5 inch diameter coaxial cable (normally yellow cable) , known as yellow cable or thick Ethernet. Up tp a maximum of 5 cable segments can be connected using repeater with maximum length of 2500 km.
  • #5: The Ethernet and IEEE 802.3 standards define a bus-topology LAN that operates at a baseband signaling rate of 10 Mbps. The graphic illustrates the three defined wiring standards: 10Base2 - known as thin Ethernet - allows network segments up to 185 meters on coaxial cable. 10Base5 - known as thick Ethernet - allows network segments up to 500 meters on coaxial cable. 10BaseT - carries Ethernet frames on twisted pair wiring The 10Base5 and 10Base2 standards provide access for several stations on the same segment. Stations are attached to the segment by a cable that runs from an attachment unit interface (AUI) in the station to a transceiver that is directly attached to the Ethernet coaxial cable. In some interfaces, the AUI and the transceiver are built in to the network interface card and no cable is required. Because the 10BaseT standard provides access for a single station only, stations attached to an Ethernet by 10BaseT are connected to a hub. The hub is analogous to an Ethernet segment, and the twisted-pair cable is analogous to the cable running between the AUI and the transceiver.
  • #7: The IEEE 802.3 10Base5 supports 10 Mbps basband transmission. The standard specifies the 0.5 inch diameter coaxial cable (normally yellow cable) , known as yellow cable or thick Ethernet. Up tp a maximum of 5 cable segments can be connected using repeater with maximum length of 2500 km. The length of 500 meters per segment is limited. This restriction is due to the maximum permissible attenuation along the cable. If the segment is too long, collision detection can not be guaranteed, since the signals may be too weak. At most 1024 stations per Ethernet is allowed. This figure is not derived from the above limitation. This restriction is intended to reduce the congestion probabilities.
  • #8: The IEEE 802.3 10Base2 supports 10 Mbps basband transmission. The standard specifies the 0.25 inch diameter coaxial cable known as cheapernet or thin Ethernet. Up tp a maximum of 5 cable segments can be connected using repeater with maximum length of 925 m. The length of 185 meters per segment is limited.
  • #9: The IEEE 802.3 10BaseT supports 10 Mbps basband transmission. The standard specifies the 24AWG Unshield Twisted Pair (UTP). Stations connect with RJ45 connector.
  • #10: 10base FP defines a passive star topology that supports up to 33 stations attached to a central passive hub. 10BaseFL is a new Fiber Optic Interrepeater Link (FOIRL) with enhanced performance. 10BaseFL connect tranceivers opposite each other or to construct a star topology around the hub. 10BaseFB defines point-to-point links with synchronous signaling. Optical signal will be retimed, hence reduced distortions. As a result, 10BaseFB can be used to cascade up to 15 repeaters.
  • #11: Nonpersistent: if the medium is busy, a station waits a random period of time and then resenses the medium is it has become free. 1-persistent: when the medium is free, any waitiong station may transmit immediately. Waiting stations therfore have aprobability of transmitting of 1 whenever it finds the channel idle.
  • #12: When a station wishes to transmit, it checks the network to determine whether another station is currently transmitting. If the network is not being used, the station proceeds with the transmission. While sending, the station monitors the network to ensure that no other station is transmitting. Two stations might start transmitting at approximately the same time if they determine that the network is available. If two stations send at the same time, a collision occurs.
  • #13: when a collision occurs, the detected station sends a 32-48 bits jam signal consists of 10101010- 10101010- 10101010- 10101010 (10101010- 10101010) bit combination [Switching technology in the local area network, M. Hein, ITP,1997]. The jam signal serves as a mechanism to cause nontranmitting stations to wait until the jam signal ends prior to attempting to transmit.
  • #14: From the perspective of these lower MAC sublayers, the service access point (SAP) process provides a convenient interface to the upper layers. These SAP entries simplify access to the shared channel up to the specified upper-layer service identified by LLC SAP entities. LLC carries two 8-bit addresses, the destination SAP and the source SAP LLC sublayer options include support for connections between applications running on the LAN, flow control to the upper layer by means of ready/not ready codes, and sequence control bits.
  • #15: The first bit of the address is Individual/Group bit Evoving 110
  • #16: From the perspective of these lower MAC sublayers, the service access point (SAP) process provides a convenient interface to the upper layers. These SAP entries simplify access to the shared channel up to the specified upper-layer service identified by LLC SAP entities. LLC carries two 8-bit addresses, the destination SAP and the source SAP LLC sublayer options include support for connections between applications running on the LAN, flow control to the upper layer by means of ready/not ready codes, and sequence control bits.
  • #19: Ethernet uses the truncated binary exponential backoff algorithm to handle collision. When a collision occurs, the station sends a jam, then ceases all tranmission.After the first collision, each station waits either 0 or 1 slot time before trying again. If two stations collide again because they pick the same random number. After the second collision, each station selects either 0,1,2 or 3 and wait that number of slot times (known as delay windows). After the k collisions, a delay window between 0 and 2k is chosen. Finally, after the tenth attempt (backoff limit), this window is limited by 1023 slot times. The attempt can continue up to the sixteenth times (attemp limit) with the same delay number. If a collision occure again, that MAC layer discard the frame and report back to upper layers for furthur recovery. The exponential growth of randomization interval ensures a low delay when only a few station collides, but also ensures that the collisons is resolved in a reasonable timel when many stations collide.
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