31-5
Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 31 Configuring IP Unicast Routing
Configuring IP Addressing on Layer 3 Interfaces
Assigning IP Addresses to Network Interfaces
An IP address identifies a location to which IP packets can be sent. Some IP addresses are reserved for
special uses and cannot be used for host, subnet, or network addresses. Table 31-2 lists ranges of IP
addresses and shows which are reserved and which are available for use. RFC 1166, “Internet Numbers,”
contains the official description of IP addresses.
An interface can have one primary IP address. A mask identifies the bits that denote the network number
in an IP address. When you use the mask to subnet a network, the mask is referred to as a subnet mask.
To receive an assigned network number, contact your Internet service provider.
IRDP Disabled.
Defaults when enabled:
• Broadcast IRDP advertisements.
• Maximum interval between advertisements: 600 seconds.
• Minimum interval between advertisements: 0.75 times max interval
• Preference: 0.
IP proxy ARP Enabled.
IP routing Disabled.
IP subnet-zero Disabled.
Table 31-1 Default Addressing Configuration (continued)
Feature Default Setting
Table 31-2 Reserved and Available IP Addresses
Class Address or Range Status
A 0.0.0.0
1.0.0.0 to 126.0.0.0
127.0.0.0
Reserved
Available
Reserved
B 128.0.0.0 to 191.254.0.0
191.255.0.0
Available
Reserved
C 192.0.0.0
192.0.1.0 to 223.255.254
223.255.255.0
Reserved
Available
Reserved
D 224.0.0.0 to 239.255.255.255 Multicast group addresses
E 240.0.0.0 to 255.255.255.254
255.255.255.255
Reserved
Broadcast
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