CANOGA PERKINS 9175 Command Reference - Manual (Page 183)

CanogaOS Command Reference
12-1
12 IP Addressing Commands
12.1 ip address
To set a primary or secondary IP address for an interface, use the ip address command in interface
configuration mode. To remove an IP address or disable IP processing, use the no form of this
command.
Command Syntax
ip address {address wildcard-mask | address/prefix-length} [secondary]
address IPv4 address.
wildcard-mask Mask for the associated IP subnet..
prefix-length Prefix length of the address.
secondary (Optional) Specifies that the configured address is a secondary IP address.
If this keyword is omitted, the configured address is the primary IP address.
Default
No IP address is defined for the interface.
Command Mode
Interface configuration
Usage
An interface can have one primary IP address and multiple secondary IP addresses. Packets generated
by the switch always use the primary IP address. Therefore, all switches and access servers on a
segment should share the same primary network number.
Hosts can determine subnet masks using the Internet Control Message Protocol (ICMP) mask request
message. Switch respond to this request with an ICMP mask reply message.
You can disable IP processing on a particular interface by removing its IP address with the no ip
address command. If the software detects another host using one of its IP addresses, it will print an
error message on the console.
The optional secondary keyword allows you to specify up to 15 secondary addresses. Secondary
addresses are treated like primary addresses, except the system never generates datagrams other than
routing updates with secondary source addresses. IP broadcasts and Address Resolution Protocol (ARP)
requests are handled properly, as are interface routes in the IP routing table.
Secondary IP addresses can be used in a variety of situations. The following are the most common
applications:
„ There may not be enough host addresses for a particular network segment. For example, your
subnetting allows up to 254 hosts per logical subnet, but on one physical subnet you need 300 host
addresses. Using secondary IP addresses on the switchs or access servers allows you to have two
logical subnets using one physical subnet.
„ Many older networks were built using Level 2 bridges. The judicious use of secondary addresses
can aid in the transition to a subnetted, router-based network. Switches on an older, bridged
segment can be easily made aware that many subnets are on that segment.