13-21
Dynamic Host Configuration Protocol (DHCP)
Managing and Troubleshooting the DHCP Server
Table 13-1. DHCP Debug Messages
Clients Unable to Receive a DHCP Address
If the router continually receives the “Processing Discover Message” event, it
is having difficulty preparing an offer for the client. One of the most common
reasons for this difficulty is that the server cannot find an available IP address.
It is possible that all available addresses are being used (view the DHCP client
bindings by entering show ip dhcp-server binding). However, it could be
that the default router for the pool is not on the same subnet as the network
address, which prevents the router from finding a valid IP address.
View the running-config (show run) and look for the DHCP pool for the clients
unable to get an address. This is the pool whose default router is the interface
to which the client connects. The address for the network should match the
network bits in the default router address.
A router interface must have its primary address on the subnet specified in
the pool in order to respond to requests. You should also check that the DHCP
network matches the address for the connecting router interface.
Client Receiving the Wrong Fixed DHCP Address
If a host is unable to get the fixed address you configured for it in a single host
DHCP pool, or if it receives an address from a different pool, check the
running-config. Make sure that you have not excluded the fixed address.
Repeated Message Possible Problem Best Next Step
Processing Discover
message
• There are no addresses
available.
• The default gateway is on
the wrong subnet.
• Check the DHCP client
bindings.
• Check settings for the
pool.
Server sent an Offer to the
Client
The client will not accept the
address and configurations.
Troubleshoot the host.
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