: VLSM

Variable Length Subnet Mask

11

- . ? , . , : . , 40, . 36., , . : , Baker Street 221B, London, United Kingdom. , . , . , IP . IP a , .

p>

IP -

IP : IP 4 (IPv4) IP 6 (IPv6). , IP 4- . .

IPv4 32- . IP- (IPv4) ( 0 255), , , 192.168.0.1. , - 11000000 10101000 00000000 00000000.

IPv6 128-. IPv6 , , 4 . : 2003:00af:café:3daf:1000:edaf:1001:afad. 16 .

IP . , . "" IP . merionet.ru 212.193.249.136. , , , 2ip.ru. IP 10, 50, 100 . , , . .

, . IP : 10.0.0.0-10.255.255.255, 172.16.0.0-172.31.255.255, 192.168.0.0-192.168.255.255. , ipconfig.

IP :

IP

IP

A

0.0.0.0

127.255.255.255

126

16777214

B

128.0.0.0

191.255.255.255

16382

65536

C

192.0.0.0

223.255.255.255

2097150

254

D

224.0.0.0

239.255.255.255

E

240.0.0.0

254.255.255.255

0.0.0.0 , , IP . DHCP , 0.0.0.0. 255.255.255.255 . 127 loopback .

D , E ( ).

IP . , - . 32- , 1. IP - , 2. , 192 1100000. . , , Windows:

192 :

1 * 27+1*26+0*25+0*24+0*23+0*27+0*21+0*20 = 1*27+1*26 = 128 + 64 = 192. :

128 64 32 16 8 4 2 1. IP , 1, 0. 1.

255

255

255

0

11111111

11111111

11111111

00000000

. A 0, B 10, 110.

. 255.0.0.0, B 255.255.0.0, C 255.255.255.0.

, . , Classless Inter-Domain Routing (CIDR), . . , , . 10.10.121.25 255.255.255.0. , C.

IP . , 40-50 . , IP . , 192.168.1.0/24, 25 . 254 . 229 .

256 , 192.168.1.0 , 192.168.1.255 . 254 . . :

H=2n 2

H , n . , 192.168.1.0 255.255.255.0. 24 , 8 . , H=28-2 = 254.

. , . , . , .

, , .

VLSM (Variable Length Subnet Mask). , IP , , .

IP IANA (Internet Assigned Numbers Authority ). , . , RIPE. , , .

, 192.168.25.0 255.255.255.0.

: 192.168.25.0/24. 24 .

, 50 . . 5 * 50 = 250 . , . . :

N = 2n

N , n IP . : 20 = 1. . , 2 : 22 = 4. , 255.255.255.192 /26. 6 64 , 62 , :

IP

IP

1

50

255.255.255.192

192.168.25.1

192.168.25.62

192.168.25.0

192.168.25.63

2

50

255.255.255.192

192.168.25.65

192.168.25.126

192.168.25.64

192.168.25.127

3

50

255.255.255.192

192.168.25.129

192.168.25.190

192.168.25.128

192.168.25.191

4

50

255.255.255.192

192.168.25.193

192.168.25.254

192.168.25.192

192.168.25.255

  Cisco Packet Tracer

Cisco Packet Tracer. , , . , , , . Access Lists. , .

, "" . "" , "" , . , 1, 1; 0, 0. :

192

168 1 125
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 1 1 1 1 1 0 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
255 255 255 0
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0
192 168 1 0

255.255.255.192. , 4, :

1

120

2

60

3

25

4

12

, , , IP . , 120 IP , - 120. 120, , 120 , 128. 64. 128 1, 64 , 192, . 25 . 32. 224 32 . 16 . 240.

: . , 256 , 32 . : 256 32 = 224. .

IP

IP

1

120

255.255.255.128

192.168.25.1

192.168.25.126

192.168.25.0

192.168.25.127

2

60

255.255.255.192

192.168.25.129

192.168.25.190

192.168.25.128

192.168.25.191

3

25

255.255.255.224

192.168.25.193

192.168.25.222

192.168.25.192

192.168.25.223

4

12

255.255.255.240

192.168.25.225

192.168.25.238

192.168.25.224

192.168.25.239

 IP

IP . 2 .

, . , .


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