P-661H/HW Series User’s Guide
Appendix E
321
Since the mask is always a continuous number of ones beginning from the left, followed by a
continuous number of zeros for the remainder of the 32 bit mask, you can simply specify the
number of ones instead of writing the value of each octet. This is usually specified by writing
a “/” followed by the number of bits in the mask after the address.
For example, 192.1.1.0 /25 is equivalent to saying 192.1.1.0 with mask 255.255.255.128.
The following table shows all possible subnet masks for a class “C” address using both
notations.
The first mask shown is the class “C” natural mask. Normally if no mask is specified it is
understood that the natural mask is being used.
Example: Two Subnets
As an example, you have a class “C” address 192.168.1.0 with subnet mask of 255.255.255.0.
The first three octets of the address make up the network number (class “C”). You want to
have two separate networks.
Divide the network 192.168.1.0 into two separate subnets by converting one of the host ID bits
of the IP address to a network number bit. The “borrowed” host ID bit can be either “0” or “1”
thus giving two subnets; 192.168.1.0 with mask 255.255.255.128 and 192.168.1.128 with
mask 255.255.255.128.
Table 131
Alternative Subnet Mask Notation
SUBNET MASK
SUBNET MASK “1” BITS
LAST OCTET BIT VALUE
255.255.255.0
/24
0000 0000
255.255.255.128
/25
1000 0000
255.255.255.192
/26
1100 0000
255.255.255.224
/27
1110 0000
255.255.255.240
/28
1111 0000
255.255.255.248
/29
1111 1000
255.255.255.252
/30
1111 1100
Table 132
Two Subnets Example
IP/SUBNET MASK
NETWORK NUMBER
HOST ID
IP Address
192.168.1.
0
IP Address (Binary)
11000000.10101000.00000001.
00000000
Subnet Mask
255.255.255.
0
Subnet Mask (Binary)
11111111.11111111.11111111.
00000000
Содержание P-661H Series
Страница 2: ......
Страница 5: ...P 661H HW Series User s Guide Certifications 5...
Страница 10: ...P 661H HW Series User s Guide 10 Customer Support...
Страница 43: ...P 661H HW Series User s Guide Chapter 1 Getting To Know Your ZyXEL Device 43 Figure 5 Connecting a Microfilter...
Страница 44: ...P 661H HW Series User s Guide 44 Chapter 1 Getting To Know Your ZyXEL Device...
Страница 76: ...P 661H HW Series User s Guide 76 Chapter 3 Wizards...
Страница 108: ...P 661H HW Series User s Guide 108 Chapter 5 LAN Setup...
Страница 132: ...P 661H HW Series User s Guide 132 Chapter 6 Wireless LAN...
Страница 191: ...P 661H HW Series User s Guide Chapter 10 Trend Micro Security Services 191 Figure 113 Security Setting ActiveX Controls...
Страница 192: ...P 661H HW Series User s Guide 192 Chapter 10 Trend Micro Security Services...
Страница 196: ...P 661H HW Series User s Guide 196 Chapter 11 Content Filtering...
Страница 202: ...P 661H HW Series User s Guide 202 Chapter 12 Introduction to IPSec...
Страница 230: ...P 661H HW Series User s Guide 230 Chapter 13 VPN Screens...
Страница 234: ...P 661H HW Series User s Guide 234 Chapter 14 Static Route...
Страница 246: ...P 661H HW Series User s Guide 246 Chapter 15 Bandwidth Management...
Страница 250: ...P 661H HW Series User s Guide 250 Chapter 16 Dynamic DNS Setup...
Страница 280: ...P 661H HW Series User s Guide 280 Chapter 19 System...
Страница 290: ...P 661H HW Series User s Guide 290 Chapter 21 Tools...
Страница 296: ...P 661H HW Series User s Guide 296 Chapter 23 Troubleshooting...
Страница 300: ...P 661H HW Series User s Guide 300 Appendix A...
Страница 304: ...P 661H HW Series User s Guide 304 Appendix C...
Страница 326: ...P 661H HW Series User s Guide 326 Appendix E...
Страница 328: ...P 661H HW Series User s Guide 328 Appendix F...
Страница 334: ...P 661H HW Series User s Guide 334 Appendix G...
Страница 368: ...P 661H HW Series User s Guide 368 Appendix K...
Страница 376: ...P 661H HW Series User s Guide 376 Figure 219 Java Sun...