ZyWALL P1 User’s Guide
Appendix B IP Subnetting
283
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 107
Alternative Subnet Mask Notation
SUBNET MASK IP ADDRESS
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 108
Two Subnets Example
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 ZyXEL ZyWALL P1
Страница 1: ...ZyWALL P1 Internet Security Appliance User s Guide Version 3 64 8 2005...
Страница 9: ...ZyWALL P1 User s Guide 8 Customer Support...
Страница 25: ...ZyWALL P1 User s Guide 24 List of Figures...
Страница 39: ...ZyWALL P1 User s Guide 38 Chapter 1 Getting to Know Your ZyWALL...
Страница 51: ...ZyWALL P1 User s Guide 50 Chapter 2 Introducing the Web Configurator...
Страница 72: ...ZyWALL P1 User s Guide Chapter 3 Wizard Setup 71 Figure 22 VPN Wizard Complete...
Страница 73: ...ZyWALL P1 User s Guide 72 Chapter 3 Wizard Setup...
Страница 91: ...ZyWALL P1 User s Guide 90 Chapter 5 WAN Screens...
Страница 116: ...ZyWALL P1 User s Guide Chapter 7 Firewall Screens 115 Figure 44 Firewall Example My Service Rule Configuration...
Страница 129: ...ZyWALL P1 User s Guide 128 Chapter 8 Introduction to IPSec...
Страница 151: ...ZyWALL P1 User s Guide 150 Chapter 9 VPN Screens...
Страница 191: ...ZyWALL P1 User s Guide 190 Chapter 12 Static Route...
Страница 215: ...ZyWALL P1 User s Guide 214 Chapter 13 Remote Management...
Страница 248: ...ZyWALL P1 User s Guide Chapter 16 Maintenance 247 Figure 134 Restart Screen...
Страница 249: ...ZyWALL P1 User s Guide 248 Chapter 16 Maintenance...
Страница 269: ...ZyWALL P1 User s Guide 268 Chapter 18 Troubleshooting...
Страница 289: ...ZyWALL P1 User s Guide 288 Appendix B IP Subnetting...
Страница 295: ...ZyWALL P1 User s Guide 294 Appendix D PPTP...
Страница 299: ...ZyWALL P1 User s Guide 298 Appendix E Triangle Route...
Страница 329: ...ZyWALL P1 User s Guide 328 Appendix H Importing Certificates...
Страница 331: ...ZyWALL P1 User s Guide 330 Appendix I Command Interpreter...
Страница 337: ...ZyWALL P1 User s Guide 336 Appendix J Firewall Commands...
Страница 341: ...ZyWALL P1 User s Guide 340 Appendix K NetBIOS Filter Commands...
Страница 347: ...ZyWALL P1 User s Guide 346 Appendix M Brute Force Password Guessing Protection...
Страница 369: ...ZyWALL P1 User s Guide 368 Index X X Auth 132 Z ZyNOS 250 ZyXEL Limited Warranty Note 4 ZyXEL s Firewall Introduction 92...