Configure DHCP Service 6500 in IOS

Keywords: dhcp server ios pool client-identifier excluded-address helper-address spantree portfast

A customer wants to migrate the dhcp server to the msfc of the 6509 switch. The requirements are complicated:

1. Allocate addresses for multiple VLAN clients at the same time

2. Some IP addresses in a VLAN are manually allocated.

3. Specify the gateway and Wins server for the customer

4. The IP address lease term for VLAN 2 is one day, and the other is three days.

5. assign a specified IP address to a specific user based on the MAC address

The final configuration is as follows:

Ip dhcp excluded-address 10.1.1.1 10.1.1.19 // address not used for Dynamic address Allocation

Ip dhcp excluded-address 10.1.1.240 10.1.1.254

Ip dhcp excluded-address 10.1.2.1 10.1.2.19

!

Ip dhcp pool global // global is the pool name, which is specified by the user

Network 10.1.0.0 255.255.0.0 // dynamically assigned address segment

Domain-name client.com//configure the domain suffix for the customer's machine

Dns-server 10.1.1.1 10.1.1.2 // configure the dns server for the client

Netbios-name-server 10.1.1.5 10.1.1.6 // configure the wins server for the client

Netbios-node-type h-node // configure the node mode for the client (this affects the smoothness of name interpretation, for example, h-node = first explain through wins server ...)

Lease 3 // address lease period: 3 days

Ip dhcp pool vlan1

Network 10.1.1.0 255.255.255.0

// This pool is a global sub-pool and inherits the domain-name option from the global pool.

Default-router 10.1.1.100 10.1.1.101 // configure the default gateway for the client

!

Ip dhcp pool vlan2 // pool configured for another VLAN

Network 10.1.2.0 255.255.255.255.0

Default-router 10.1.2.100 10.1.2.101

Lease 1

!

Ip dhcp pool vlanw.john // always allocates a... address for the host whose MAC address is...

Host 10.1.1.21 255.255.255.0

Client-identifier 010050. bade.6384 // client-identifier = 01 with the client NIC address

!

Ip dhcp pool vlan1_tom

Host 10.1.1.50 255.255.255.0

Client-identifier 010010.3ab1.eac8

Related DHCP Debugging commands:

No service dhcp // stop the DHCP service [DHCP service is enabled by default]

Sh ip dhcp binding // displays Address allocation information

Show ip dhcp conflict // display address conflict

Debug ip dhcp server {events | packets | linkage} // observe the working status of the DHCP server

If the DHCP client is not assigned an IP address, there are two common causes. The first case is that the port connecting to the client is not set to Portfast. After the MS Client is started, it checks that the network adapter is connected normally. When the Link is UP, it starts to send the DHCPDISCOVER request. At this time, the switch port is undergoing Spanning Tree computing and generally takes 30-50 seconds to enter the forwarding status. If the MS client does not receive a response from the dhcp server, it will set a 169.169.X.X IP address for the NIC. The solution is to set the switch port to Portfast mode: CatOS (4000/5000/6000): set spantree portfast mod_num/port_num enable; IOS (2900/3500): interface ...; spanning-tree portfast.

In another case, the DHCP server and the DHCP workstation are not in the same VLAN. In this case, we usually set the ip helper-address to solve the problem:

Interface vlan1

Ip address 10.1.1.254 255.255.255.0 // assume that the DHCP server address is 10.1.1.8

Interface Vlan2

Ip address 10.1.2.254 255.255.255.0

Ip helper-address 10.1.1.8 // assume this is the VLAN of the DHCP Client

Reference webpage:

DHCP locking ing [[The No. x Link End.]

DHCP Commands

Ip helper-address

Portfast

Article entry: csh responsible editor: csh