128
C
HAPTER
15: IP A
DDRESS
C
ONFIGURATION
Subnet and Mask
The traditional IP address classification method wastes IP addresses greatly. In
order to make full use of the available IP addresses, the concepts of mask and
subnet were introduced.
A mask is a 32-bit number corresponding to an IP address. The number consists of
1s and 0s. A mask is defined as follows: the bits of the network number and
subnet number are set to 1, and the bits of the host number are set to 0. The
mask divides the IP address into two parts: subnet address and host address. In an
IP address, the part corresponding to the “1” bits in the mask is the subnet
Table 73
Classes and ranges of IP addresses
Network
type Address
range
IP network
range Description
A 0.0.0.0
to
127.255.255.255
1.0.0.0 to
126.0.0.0
■
An IP address with all 0s host ID is a
network address and is used for
network routing.
■
An IP address with all 1s host ID is a
broadcast address and is used for
broadcast to all hosts on the
network.
■
The IP address 0.0.0.0 is used by
hosts when they are booted but is
not used afterward.
■
An IP address with all 0s network ID
represents a specific host on the
local network and can be used as a
source address but cannot be used
as a destination address.
■
All the IP addresses in the format of
127.X.Y.Z are reserved for loopback
test and the packets sent to these
addresses will not be output to
lines; instead, they are processed
internally and regarded as incoming
packets.
B 128.0.0.0
to
191.255.255.255
128.0.0.0 to
191.255.0.0
■
An IP address with all 0s host ID is a
network address and is used for
network routing.
■
An IP address with all 1s host ID is a
broadcast address and is used for
broadcast to all hosts on the
network.
C 192.0.0.0
to
223.255.255.255
192.0.0.0 to
223.255.255.0
■
An IP address with all 0s host ID is a
network address and is used for
network routing.
■
An IP address with all 1s host ID is a
broadcast address and is used for
broadcast to all hosts on the
network.
D 224.0.0.0
to
239.255.255.255
None
Class D addresses are multicast
addresses.
E 240.0.0.0
to
255.255.255.254
None
These IP addresses are reserved for
future use.
Others 255.255.255.255 255.255.255.25
5
255.255.255.255 is used as a LAN
broadcast address.
Summary of Contents for Switch 7757
Page 32: ...32 CHAPTER 1 CLI OVERVIEW...
Page 70: ...70 CHAPTER 5 LOGGING IN USING MODEM...
Page 76: ...76 CHAPTER 7 LOGGING IN THROUGH NMS...
Page 86: ...86 CHAPTER 9 CONFIGURATION FILE MANAGEMENT...
Page 120: ...120 CHAPTER 13 ISOLATE USER VLAN CONFIGURATION...
Page 126: ...126 CHAPTER 14 SUPER VLAN...
Page 136: ...136 CHAPTER 16 IP PERFORMANCE CONFIGURATION...
Page 152: ...152 CHAPTER 17 IPX CONFIGURATION...
Page 164: ...164 CHAPTER 19 QINQ CONFIGURATION...
Page 172: ...172 CHAPTER 21 SHARED VLAN CONFIGURATION...
Page 182: ...182 CHAPTER 22 PORT BASIC CONFIGURATION...
Page 198: ...198 CHAPTER 24 PORT ISOLATION CONFIGURATION...
Page 208: ...208 CHAPTER 25 PORT SECURITY CONFIGURATION...
Page 224: ...224 CHAPTER 27 DLDP CONFIGURATION...
Page 232: ...232 CHAPTER 28 MAC ADDRESS TABLE MANAGEMENT...
Page 240: ...240 CHAPTER 29 CENTRALIZED MAC ADDRESS AUTHENTICATION CONFIGURATION...
Page 280: ...280 CHAPTER 30 MSTP CONFIGURATION...
Page 348: ...348 CHAPTER 35 IS IS CONFIGURATION...
Page 408: ...408 CHAPTER 39 802 1X CONFIGURATION...
Page 412: ...412 CHAPTER 40 HABP CONFIGURATION...
Page 422: ...422 CHAPTER 41 MULTICAST OVERVIEW...
Page 426: ...426 CHAPTER 42 GMRP CONFIGURATION...
Page 480: ...480 CHAPTER 47 PIM CONFIGURATION...
Page 506: ...506 CHAPTER 48 MSDP CONFIGURATION...
Page 552: ...552 CHAPTER 51 TRAFFIC ACCOUNTING CONFIGURATION...
Page 570: ...570 CHAPTER 53 HA CONFIGURATION...
Page 582: ...582 CHAPTER 54 ARP CONFIGURATION SwitchA arp protective down recover interval 200...
Page 622: ...622 CHAPTER 58 DHCP RELAY AGENT CONFIGURATION...
Page 684: ...684 CHAPTER 61 QOS CONFIGURATION...
Page 718: ...718 CHAPTER 63 CLUSTER...
Page 738: ...738 CHAPTER 67 UDP HELPER CONFIGURATION...
Page 752: ...752 CHAPTER 69 RMON CONFIGURATION...
Page 772: ...772 CHAPTER 70 NTP CONFIGURATION...
Page 796: ...796 CHAPTER 72 FILE SYSTEM MANAGEMENT...
Page 802: ...802 CHAPTER 73 BIMS CONFIGURATION...
Page 814: ...814 CHAPTER 74 FTP AND TFTP CONFIGURATION...
Page 830: ...830 CHAPTER 75 INFORMATION CENTER...
Page 836: ...836 CHAPTER 76 DNS CONFIGURATION...
Page 852: ...852 CHAPTER 77 BOOTROM AND HOST SOFTWARE LOADING...
Page 858: ...858 CHAPTER 78 BASIC SYSTEM CONFIGURATION DEBUGGING...