An example of a little information can be a bad thing. I’d always thought that the ’service dhcp’ command enabled the dhcp server and client abilities of a device. It finally donned on me that that’s why my DHCP relay agent wasn’t working. Oops. Here’s an exerpt of the Cisco Command Reference:
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service dhcp
To enable the Cisco IOS Dynamic Host Configuration Protocol (DHCP) server and relay agent features on your router, use the service dhcp command in global configuration mode. To disable the Cisco IOS DHCP server and relay agent features, use the no form of this command.
service dhcp
no service dhcp
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Global configuration
Command History
Usage Guidelines
The BOOTP and DHCP servers in Cisco IOS software both use the ICMP port (port 67) by default. ICMP "port unreachable messages" will only be returned to the sender if both the BOOTP server and DHCP server are disabled. Disabling only one of the servers will not result in ICMP port unreachable messages.
