380 Auto Image and Configuration Update
A network DHCP server returns the following information:
• IP address and subnet mask to be assigned to the interface
• IP address of a default gateway, if needed for IP communication
After an IP address is assigned to the switch, if a hostname is not already
assigned, Auto Configuration issues a DNS request for the corresponding
hostname. This hostname is also displayed as the CLI prompt (as in response
to the hostname command).
Obtaining Other Dynamic Information
The following information is also processed and may be returned by a
BOOTP or DHCP server:
• Name of configuration file (the
file
field in the DHCP header or option
67) to be downloaded from the TFTP server.
• Identification of the TFTP server providing the file. The TFTP server can
be identified by name or by IP address as follows:
– hostname: DHCP option 66 or the
sname
field in the DHCP header)
– IP address: DHCP option 150 or the
siaddr
field in the DHCP header
When a DHCP OFFER identifies the TFTP server more than once, the
DHCP client selects one of the options in the following order:
sname
, option
66, option 150,
siaddr
. If the TFTP server is identified by hostname, a DNS
server is required to translate the name to an IP address.
The DHCP client on the switch also processes the name of the text file
(option 125, the V-I vendor-specific Information option) which contains the
path to the image file.
Obtaining the Image
Auto Configuration attempts to download an image file from a TFTP server
only if no configuration file was found in the internal flash or a USB drive, or
even with a saved configuration file that has Auto Configuration enabled.
The network DHCP server returns a DHCP OFFER message with option
125. When configuring the network DHCP server for image downloads, you
must include Option 125 and specify the Dell Enterprise Number, 674.
Within the Dell section of option 125, sub option 5 must specify the path and
name of a file on the TFTP server. This file is not the image file itself, but
rather a text file that contains the path and name of the image file. Upon
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