Problem: Clients are not receiving an IP address or their configuration information

 

Problems might occur if the clients cannot receive an IP address or the configuration information. An IP address is leased to a client through a four-step process between the client and the Dynamic Host Configuration Protocol (DHCP) server.

All four steps must take place before the client receives an IP address. Refer to the DHCP client/server interaction topic for details about the four-step process.

Here are some common reasons for this problem.

The client is connected to a subnet that is not configured in the DHCP server.

Check the DHCP configuration and verify that all subnets managed by the DHCP server are listed in the configuration. If you are unsure about which subnets should be managed by the DHCP server, refer to Network topology considerations.

The DHCP DISCOVER message from the client cannot reach the DHCP server.

If the DHCP server does not have an IP address on the client's subnet, there must be a router or DHCP/BOOTP relay agent that can forward the client's DHCP DISCOVER message to the DHCP server. For more information, refer to Relay agents and routers. In addition to receiving the broadcast message, the server needs to be able to send reply packets back to the client's subnet.

If your System i™ model is multihomed, you might need to add a subnet group to the DHCP configuration. For more detail about configuring DHCP for a multihomed system, see Example: DHCP and multihoming. This example describes what needs to be done to the DHCP configuration so that the client's broadcast message is received by the system.

The DHCP server does not have any available addresses for the client in the address pool.

You can use the DHCP server monitor to see which addresses are currently being used by the DHCP server. Managing leased IP addresses provides more details about using the DHCP server monitor. If the DHCP server has run out of available addresses, you might need to add more IP addresses to the address pool, shorten the lease time, or delete permanent leases that are no longer required.

 

Parent topic:

Troubleshooting DHCP