Lub npog ntsej muag subnet 255.255.255.0 chaw nyob yog lub ntsej muag subnet ntau tshaj plaws siv hauv cov khoos phis tawj txuas nrog Internet Protocol (IPv4) tes hauj lwm. Dhau li ntawm nws siv hauv tsev network routers, koj kuj yuav ntsib lub npog ntsej muag no ntawm kev xeem ntawv pov thawj network xws li CCNA.
255.255.255.0 thiab Subnetting
Subnets ua raws li lub laj kab virtual, faib ib qho thaiv ntawm IP chaw nyob rau hauv me me. Qhov kev xyaum no daws cov teeb meem hauv network thiab tso cai rau kev nkag mus rau hauv cov subnets. Lub npog ntsej muag subnet txheeb xyuas tus kheej subnets.
Tib txwm subnets ua haujlwm nrog cov koom tes hauv chav kawm uas faib cov chaw nyob IP rau hauv ib qho ntawm tsib chav kawm (Class A / B / C / D / E) raws li tus nqi ntawm tus IP chaw nyob.
Lub ntsej muag subnet 255.255.255.0 hloov mus rau 32-ntsis binary tus nqi:
11111111 111111111 11111111 0000000
Tus lej 0 ntawm lub npog ntsej muag no nthuav dav IP ntau ntawm subnet-8 khoom lossis txog 256 qhov chaw nyob hauv qhov no. Ib tug loj ntawm cov subnetworks me me kuj txhais tau los ntawm kev hloov kho daim npog qhov ncauj raws li qhia nyob rau hauv cov lus hauv qab no.
| Classful Subnets Raws li 255.255.255 Mask Prefix | ||
|---|---|---|
| Mask | Subnetworks | Nodes/Subnet |
| 255.255.255.0 | 1 | 254 |
| 255.255.255.128 | 2 | 126 |
| 255.255.255.192 | 4 | 62 |
| 255.255.255.224 | 8 | 30 |
| 255.255.255.240 | 16 | 14 |
| 255.255.255.248 | 32 | 6 |
| 255.255.255.252 | 64 | 2 |
Ib qho teeb meem tsis raug subnet mask (tseem hu ua netmask) tuaj yeem yog vim li cas koj tsis tuaj yeem txuas rau hauv internet.
Subnets thiab CIDR
Nyob rau hauv cov txheej txheem chav kawm ib txwm muaj, ntau qhov chaw nyob IP uas tsis siv tau raug nkim vim tias cov chaw muab kev pabcuam hauv internet thiab cov tuam txhab loj tau tseg qhov chaw nyob thaiv uas tsis tuaj yeem sib koom. Ntau lub hauv internet tom qab hloov mus rau qhov tsis muaj chav kawm IP sib txuas los txhawb kev faib cov cai yooj yim thiab tiv thaiv qhov kev xav tau ntawm IPv4 qhov chaw nyob hauv internet hauv xyoo 1990s.
Classless tes hauj lwm hloov pauv cov kev sawv cev ntawm subnet ib txwm ua rau cov lus luv luv raws li tus lej ntawm 1 tus lej hauv daim npog ntsej muag. Classless Inter-Domain Routing (CIDR) shorthand sau tus IP chaw nyob thiab nws lub npog ntsej muag sib txuas hauv daim ntawv:
xxx.xxx.xxx.xxx/n
Ntawm no, sawv cev rau tus lej ntawm 1 txog 31 uas yog tus lej ntawm 1 khoom hauv lub npog ntsej muag.
CIDR txhawb nqa IP chaw nyob tsis muaj chav kawm thiab koom nrog lub ntsej muag lub ntsej muag nrog tus lej IP network ywj pheej ntawm lawv cov chav kawm ib txwm muaj. Routers uas txhawb CIDR lees paub cov tes hauj lwm no raws li tus kheej txoj hauv kev, txawm tias lawv tuaj yeem sawv cev rau kev sib sau ua ke ntawm ntau lub subnets.
kab hauv qab
Lub koom haum InterNIC tswj hwm cov npe hauv internet thiab faib IP chaw nyob rau hauv cov chav kawm. Feem ntau ntawm cov no yog cov chav kawm A, B, thiab C. Cov chav kawm C siv lub ntsej muag lub ntsej muag ua ntej ntawm 255.255.255.0.
Siv 255.255.255.0 ua tus IP chaw nyob
Txawm hais tias tau hais tawm hauv daim ntawv tus lej IP chaw nyob, cov khoom siv network siv 255.255.255.0 ua lub npog ntsej muag thiab tsis yog qhov chaw nyob IP ua haujlwm. Kev sim siv tus lej no (lossis ib tus lej IP uas pib nrog 255) raws li qhov chaw nyob ntawm lub cuab yeej ua rau kev sib txuas ntawm tus IP tsis ua haujlwm vim yog lub ntsiab lus ntawm tus lej ntau ntawm IP networks.
