IPV4 pob ntawv hom

(1)Lub versiondaim teb tso nyiaj rau 4 cov khoom, qhia txog qhov version ntawm IP raws tu qauv.
(2)IP Header Length, daim teb no yog siv los piav txog qhov ntev ntawm tus IP header, vim tias muaj qhov sib txawv ntawm qhov kev xaiv xaiv nyob hauv IP header. Ntu no occupies 4 khoom, nrog ib tug ntev chav tsev ntawm 4 bytes, uas txhais tau hais tias tus nqi nyob rau hauv lub cheeb tsam no = IP header length (in bytes) / ntev unit (4 bytes).
(3)Hom Kev Pabcuam: 8bit dwb.
PPP: Thawj peb tus lej txhais qhov tseem ceeb ntawm pob. Qhov tseem ceeb tshaj tus nqi yog, qhov tseem ceeb dua cov ntaub ntawv loj yog
000 (Routine) Ib txwm
001 (Priority) qhov tseem ceeb, siv rau cov ntaub ntawv lag luam
010 (Tswj) tam sim, rau cov ntaub ntawv lag luam
011 (Flash) flash ceev rau lub suab kis tau tus mob
100 (Flash Overrides) ceev ceev rau kev lag luam video
101 (tseem ceeb) CRI/TIC/ECP tseem ceeb rau lub suab kis tau tus mob
110 (Internet Control) Inter network tswj, siv rau kev tswj lub network, xws li cov kev cai tswj
111 (Network Control) network tswj, siv rau kev tswj lub network
DTRCO: 5 tus lej kawg
(1000) D ncua: 0: min ncua, 1: txo qis kom ntau li ntau tau
(0100) T Throughput: 0: max throughput (siab tshaj plaws throughput), 1: Sim ua kom cov tsheb khiav ntau li ntau tau
(0010) R kev ntseeg tau: 0: max throughput, 1: maximize kev ntseeg
(0001) M kis tus nqi: 0: min hnub Monday tus nqi (yam tsawg kawg nkaus nyiaj siv ua haujlwm), 1: txo tus nqi kom ntau li ntau tau
(0000): ib txwm (kev pabcuam tsis tu ncua).
(4)Tag nrho ntev ntawm IP pob ntawv: 16 bits in length. Qhov ntev ntawm ib pob ntawv IP suav hauv bytes (xws li header thiab cov ntaub ntawv), yog li qhov ntev tshaj plaws ntawm IP pob ntawv yog 65 535 bytes. Yog li, qhov loj ntawm pob ntawv payload = Tag nrho IP pob ntawv ntev - IP header ntev.
(5)Tus cim: 16 bits in length. Daim teb no yog siv ua ke nrog cov Chij thiab Fragment Offer teb rau ntu cov pob ntawv loj dua. Tom qab lubroutersplits ib pob ntawv, tag nrho cov pob ntawv me me uas tau faib yog cim nrog tib tus nqi, yog li cov khoom siv lo lus uas peb tuaj yeem paub qhov txawv ntawm cov pob ntawv twg yog cov pob ntawv cais.
(6)Chij: 3 ntsis hauv qhov ntev.
Thawj tus lej ntawm daim teb no tsis siv.
Qhov thib ob me ntsis yog DF (Tsis txhob Fragment) me ntsis. Thaum DF ntsis yog teem rau 1, nws qhia tau hais tias tusroutertsis tuaj yeem segment lub pob ntawv txheej sab saud. Yog tias cov pob ntawv txheej sab saud tsis tuaj yeem xa mus yam tsis muaj segmentation, lubrouteryuav muab pov tseg cov ntaub ntawv txheej sab sauv thiab xa cov lus yuam kev.
Qhov thib peb me ntsis yog MF (Ntau Fragments) me ntsis. Thaum lubrouterntu ib pob ntawv txheej sab saud, nws teev cov MF me ntsis rau 1 hauv header ntawm IP pob ntawv tshwj tsis yog rau ntu kawg.
(7)Fragment Offset: Ib qhov ntev ntawm 13 khoom, ntsuas hauv units ntawm 8 octets. Qhia qhov chaw ntawm pob ntawv IP nyob rau hauv cov pob khoom tivthaiv, uas yog siv los ntawm qhov kawg tau txais los sib sau ua ke thiab kho cov pob ntawv IP.
(8)Lub Sijhawm Ua Neej (TTL): Qhov ntev yog 8 khoom, pib tsim hauv vib nas this (s), tab sis qhov tseeb ntsuas hauv hops. Tus nqi raug pom zoo yog 64. Thaum IP pob ntawv raug xa mus, tus nqi tshwj xeeb yog thawj zaug rau daim teb no. Thaum ib pob ntawv IP hla dhau txhua qhovrouterraws txoj kev, txhua tusrouterraws li txoj kev yuav txo tus nqi TTL ntawm IP pob ntawv los ntawm 1. Yog tias TTL raug txo rau 0, lub pob IP yuav raug muab pov tseg. Daim teb no tuaj yeem tiv thaiv IP pob ntawv los ntawm kev xa mus tsis tu ncua hauv lub network vim muaj kev sib txuas lus.
(9)raws tu qauv: 16 bits in length. Siv rau kev txheeb xyuas qhov tseeb ntawm IP headers, tab sis tsis suav nrog cov ntaub ntawv seem. Vim txhua tusrouteryuav tsum tau hloov tus nqi TTL, lubrouteryuav rov xam tus nqi no rau txhua pob ntawv hla dhau
(10)Header Checksum: 16 bits in length. Siv rau kev txheeb xyuas qhov tseeb ntawm IP headers, tab sis tsis suav nrog cov ntaub ntawv seem. Vim txhua tusrouteryuav tsum tau hloov tus nqi TTL, lubrouteryuav rov xam tus nqi no rau txhua pob ntawv hla dhau
(11)Qhov chaw nyob thiab qhov chaw nyob: Ob qhov chaw nyob yog 32 ntsis. Txheeb xyuas lub hauv paus chiv keeb thiab chaw nyob ntawm tus IP pob ntawv no. Thov nco ntsoov tias tshwj tsis yog siv NAT, ob qhov chaw nyob no yuav tsis hloov pauv tag nrho cov txheej txheem sib kis.
(12)Kev xaiv: Qhov no yog qhov sib txawv ntawm qhov ntev. Daim teb no yog xaiv tau thiab feem ntau yog siv rau kev sim, thiab tuaj yeem sau rov qab los ntawm cov cuab yeej tsim khoom raws li xav tau. Cov khoom xaiv tau muaj xws li cov hauv qab no:

• Loose source routing: Muab ib tug series ntawm IP chaw nyob raurouterinterfaces. Cov pob ntawv IP yuav tsum raug xa mus raws cov chaw nyob IP no, tab sis nws raug tso cai hla ntau lub routers ntawm ob qhov chaw nyob IP sib law liag.
• nruj qhov chaw routing: Muab ib tug series ntawm IP chaw nyob raurouterinterfaces. Cov pob ntawv IP yuav tsum raug xa mus raws li cov chaw nyob IP no, thiab yog tias lub hop tom ntej tsis nyob hauv lub rooj IP chaw nyob, nws qhia tau hais tias qhov yuam kev.
• Sau txoj kev: Sau tus IP chaw nyob ntawm tus router lub outbound interface thaum tus IP pob ntawv tawm txhuarouter.
• Cov ntawv teev sijhawm: Sau lub sij hawm thaum ib pob ntawv IP tawm txhuarouter.
• Padding: Vim hais tias chav tsev ntawm IP header ntev yog 32 me ntsis, qhov ntev ntawm tus IP header yuav tsum yog qhov ntau ntau ntawm 32 khoom. Yog li ntawd, tom qab qhov kev xaiv xaiv, tus IP raws tu qauv yuav sau rau hauv ob peb xoom kom ua tiav ib qho ntau ntawm 32 khoom.
IPV4 cov ntaub ntawv feem ntau tuaj yeem siv rau peb lub tuam txhabONUnetwork pab kiag li lawm, thiab peb muaj feem xyuam nrog network kub muag khoom npog ntau homONUseries khoom, nrog rau ACONU/ kev sib txuas lusONU/ ntseONU/ lub thawvONU, thiab lwm yam saum toj noONUseries cov khoom siv tuaj yeem siv rau cov kev xav tau hauv network hauv ntau yam xwm txheej. Zoo siab txais tos txhua tus tuaj thiab muaj kev nkag siab ntau ntxiv txog cov khoom.