Dhcp Autoconfiguration; Dhcp Auto-Image Update; Limitations And Restrictions - Cisco ME 3400 Software Configuration Manual

Chapter 3 Assigning the Switch IP Address and Default Gateway

DHCP Autoconfiguration

DHCP autoconfiguration downloads a configuration file to one or more switches in your network from
a DHCP server. The downloaded configuration file becomes the running configuration of the switch. It
does not over write the bootup configuration saved in the flash, until you reload the switch.

DHCP Auto-Image Update

You can use DHCP auto-image upgrade with DHCP autoconfiguration to download both a configuration
and a new image to one or more switches in your network. The switch (or switches) downloading the
new configuration and the new image can be blank (or only have a default factory configuration loaded).
If the new configuration is downloaded to a switch that already has a configuration, the downloaded
configuration is appended to the configuration file stored on the switch. (Any existing configuration is
not overwritten by the downloaded one.)
To enable a DHCP auto-image update on the switch, the TFTP server where the image and configuration
Note
files are located must be configured with the correct option 67 (the configuration filename), option 66
(the DHCP server hostname) option 150 (the TFTP server address), and option 125 (description of the
file) settings.
For procedures to configure the switch as a DHCP server, see the
Autoconfiguration" section on page 3-6
Services" section of the
After you install the switch in your network, the auto-image update feature starts. The downloaded
configuration file is saved in the running configuration of the switch, and the new image is downloaded
and installed on the switch. When you reboot the switch, the configuration is stored in the saved
configuration on the switch.

Limitations and Restrictions

These are the limitations:
•
•
•
The configuration file that is downloaded from TFTP is merged with the existing configuration in the
Note
running configuration but is not saved in the NVRAM unless you enter the write memory or
copy running-configuration startup-configuration privileged EXEC command. Note that if the
downloaded configuration is saved to the startup configuration, the feature is not triggered during
subsequent system restarts.
OL-9639-07
Cisco IOS IP Configuration Guide, Release
The DHCP-based autoconfiguration with a saved configuration process stops if there is not at least
one Layer 3 interface in an up state without an assigned IP address in the network.
Unless you configure a timeout, the DHCP-based autoconfiguration with a saved configuration
feature tries indefinitely to download an IP address.
The auto-install process stops if a configuration file cannot be downloaded or it the configuration
file is corrupted.
and the "Configuring DHCP" section of the "IP addressing and
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
Assigning Switch Information
"Configuring DHCP-Based
12.2.
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