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User Guidelines
The ip address dhcp command allows any interface to dynamically learn its IP address by using the DHCP protocol.
Some DHCP Servers require that the DHCPDISCOVER message have a specific host name. The most typical usage of
the ip address dhcp hostname host-name command is when host-name is the host name provided by the system
administrator.
If a router is configured to obtain its IP address from a DHCP server, it sends a DHCPDISCOVER message to provide
information about itself to the DHCP server on the network.
If the ip address dhcp command is used with or without the optional keyword, the DHCP option 12 field (host name
option) is included in the DISCOVER message. By default, the specified DHCP host name is the device globally configured
host name.
When the device is reset, the DHCP command is saved in the configuration file, but the IP address is not. It is
recommended not to define a DHCP address on an inband port or LAG. If a DHCP IP address is configured, this address
is dynamically retrieved, and the "ip address dhcp" command is saved in the configuration file. In the event of a master
failure, the backup will again attempt to retrieve a DHCP address. This could result in one of the following:
§
The same IP address may be assigned;
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A different IP address may be assigned, which could result in loss of connectivity to the management station;
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The DHCP server may be down, which would result in IP address retrieval failure, and possible loss of connectivity
to the management station.
Example
The following example acquires an IP address on an Ethernet interface from DHCP.
Console (config)# interface ethernet g8
Console (config-if)# ip address dhcp
3.10.4 ip default-gateway
The ip default-gateway command defines a default gateway (router). To remove the default gateway use the no form of
this command.
Syntax
ip default-gateway ip-address
no ip default-gateway
ip-address — Valid IP address that specifies the IP address of the default gateway.
§
Default Configuration
No default gateway is defined.
Command Mode
Interface configuration (Out-of-band-eth)
User Guidelines
The setting of the default gateway on the out-of-band port must not precede the assignment of the IP address.
Always assign the IP address to the out-of-band port first, and then set the default gateway.
Example
The following example defines an ip default gateway.
Console(config)# interface out-of-band-eth 1
Console (config-oob)# ip address 192.168.1.23
Console (config-oob)# ip default-gateway 192.168.1.1
3.10.5 show ip interface
The show ip interface user EXEC command displays the usability status of interfaces configured for IP.
Syntax
show ip interface [ethernet interface-number | vlan vlan-id | port-channel number | out-of-band-eth oob-interface]]
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