: VLSM
Variable Length Subnet Mask
- . ? , . , : . , 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. , , . , , , . 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 . 2 .
, . , .