DHCP Client configuration command directory

ip address dhcp

ip dhcp client

ip dhcp-server

show dhcp lease

show dhcp server

debug dhcp

This chapter describes the DHCP configuration command. You can use the command introduced in this chapter to configure and monitor the operation of DHCP protocol on the router.

For information about configuration, please refer to “configure DHCP”.

ip address dhcp

In order to acquire an IP address for the Ethernet interface by Dynamic host configuration protocol (DHCP), you can use interface configuration command “ip address dhcp”. You can use “no” form of this command to delete the acquired IP address.

ip address dhcp

no ip address dhcp

Parameter

none

Default

none

Command mode

Interface configuration mode

Explanation

Command “ip address dhcp” allows the interface to acquire IP address by DHCP protocol, which is extremely useful for the dynamic connection with internet service provider (ISP) by the Ethernet interface. As long as it acquires the dynamic IP address, the Ethernet can use port alteration technology (PAT) to implement network address translation (NAT).

IF the router is configured command “ip address dhcp”, the router will send “DHCP Discover” information to the DHCP server on the network.

If the router is configured command “no ip address dhcp”, the router will send “DHCP RELEASE” information.

Example

The following example enables the ethernet1/1 interface to acquire IP address of the interface by DHCPprotocol.

!
interface Ethernet1/1
 ip address dhcp
 

Related commands

ip dhcp client

ip dhcp-server

show dhcp lease

show dhcp server

ip dhcp client

Configure the parameter of local router DHCP client

ip dhcp client { minlease seconds | retransmit count | select seconds }

no ip dhcp client { minlease | retransmit | select }

Parameter

minlease seconds  (Optional) minimum lease time acceptable, ranges from 60 seconds to 86400 seconds.

retransmit count (Optional) retransmit times of protocol packet, range from 1 to 10.

select seconds  (optional) time inside selected, ranges from 0 to 30.

Default

minlease:Default value of parameter “minlease” is 60 seconds.

retransmit:Default value of parameter “retransmit” is 4 times.

select:Default value of parameter “select is 0 second.

Command mode

global configuration mode

Explanation

Adjust these parameters according to the requirement of the network structure and DHCPserver.

If “no” form of these commands are configured, then these parameters will be reset to the default value defined by the system.

Example

The following example configures the minimum leasing time acceptable of the DHCP client on the router to 100 seconds.

ip dhcp client minlease 100

The following example configures the retransmit times of the protocol packet of DHCP client on the router to 3 times.

ip dhcp client retransmit 3

The following example configures the interval selected of DHCP client on the router to 10 seconds.

ip dhcp client select 10

Related commands

ip address dhcp

ip dhcp-server

show dhcp lease

show dhcp server

ip dhcp-server

You can use command “ip dhcp-server” to designate the IP address of DHCP server which can designate the acknowledged DHCPserver

ip dhcp-server ip-address

no ip dhcp-server ip-address

Parameter

ip-address  IP address of DHCPserver.

Default

Without any default IP address of DHCPserver.

Command mode

global configuration mode

Explanation

Use this command to designate an IP address of DHCPserver, the command will not replace the previously designated IP address of DHCP server.

 “No” forma of this command can be used to clear the previously configured IP address of DHCPserver.

Example

The following example shows how to designate the server with IP address of 192.168.20.1 as the DHCP server on the router:

ip dhcp-server 192.168.20.1

Related commands

ip address dhcp

ip dhcp client

show dhcp lease

show dhcp server

show dhcp lease

You can use command “show dhcp lease” to check the allocated information of DHCP server used by the current router.

Show dhcp lease

Parameter

none

Default

none

Command mode

管理态

Explanation

使用此命令可以查看当前路由器所使用的DHCP服务器分配的信息。

Example

Use this command to check the allocated information of DHCPserver currently used by the router.

router#show dhcp lease
Temp IP addr: 192.168.20.3  for peer on Interface: Ethernet1/1
Temp  sub net mask: 255.255.255.0
   DHCP Lease server: 192.168.1.3, state: 4 Rebinding
   DHCP transaction id: 2049
   Lease: 86400 secs,  Renewal: 43200 secs,  Rebind: 75600 secs
Temp default-gateway addr: 192.168.1.2
   Next timer fires after: 02:34:26
   Retry count: 1   Client-ID: router-0030.80bb.e4c0-Et1/1

Related commands

ip address dhcp

ip dhcp client

ip dhcp-server

show dhcp server

debug dhcp

show dhcp server

You can use command “show dhcp server” to show the acknowledged information of DHCPserver.

show dhcp server

Parameter

none

Default

none

Command mode

supervisor mode

Explanation

Use this command to show the acknowledged DHCPserver information.

Example

The following example shows the acknowledged DHCPserver information.

router#show dhcp sever

DHCP server: 255.255.255.255

  Leases:  0

  Discovers: 62 Requests: 0     Declines: 0     Releases: 0

  Offers:    0  Acks:     0     Naks:     0     Bad:      0

  Subnet: 0.0.0.0,      Domain name:

Related commands

ip address dhcp

ip dhcp client

ip dhcp-server

show dhcp lease

debug dhcp

When dhcp is functioning on the router, you can use command “debug dhcp” to check the processing situation of dhcpprotocol.

debug dhcp <detail>

no debug dhcp <detail>

Parameter

detail:show the packet content of DHCPprotocol

Default

It does not show any related information by default.

Command mode

管理态

Explanation

Show some important processing information about DHCP processing, example is as follows:

router#debug dhcp

router#2000-4-22 10:50:40 DHCP: Move to INIT state, xid: 0x7

2000-4-22 10:50:40 DHCP: SDISCOVER attempt # 1, sending 277 byte DHCP packet

2000-4-22 10:50:40 DHCP:        B'cast on Ethernet1/1 interface from 0.0.0.0

2000-4-22 10:50:40 DHCP: Move to SELECTING state, xid: 0x7

2000-4-22 10:50:46 DHCP: SDISCOVER attempt # 2, sending 277 byte DHCPpacket

2000-4-22 10:50:46 DHCP:        B'cast on Ethernet1/1 interface from 0.0.0.0

2000-4-22 10:50:54 DHCP: SDISCOVER attempt # 3, sending 277 byte DHCPpacket

Related commands

show dhcp lease