Cisco Catalyst 4500 Series Software Configuration Manual page 320

Configuring Programmability Components
3.
4.
5.
Figure 6-2
Autoboot with
option 4, 5 or 6
Validate data
Configure management
interface with DHCP data
(IP, subnet mask, gateway,
DNS server*
DHCP data for later download
Boot kernel from image
Replace the existing system startup-
configuration files with downloaded
startup-configuration files
Continue booting Cisco IOS
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
6-8
The switch sends the DHCP request for the IP address.
The switch receives the DHCP acknowledgment packet from the server, downloads the image
specified in the filename variable in the DHCP server, and then boots up with downloaded
image.
While booting, the switch receives the Option 43 list from the DHCP server with information
about the location of configuration file, script file and ova file to be downloaded.
After POST is complete, the switch looks for the startup configuration files, script files, and ova
files as mentioned in the Option 43 list received in Step 4. If the files mentioned the Option 43
list are present in the specified location, the switch downloads them.
The script file is downloaded to— bootflash:pxe/scripts folder
The ova file is downloaded to— bootflash:pxe/ova folder.
PXE Boot Process Flow
ROMMON
DHCP_DISCOVER
DHCP_OFFER
DHCP_REQUEST
DHCP_ACK
HTTP or TFTP download (Image) - start
HTTP or TFTP download (Image) - complete
HTTP or TFTP download - start
(startup-config, scripts, and ova files)
HTTP or TFTP download - complete
(startup-config, scripts, and ova files)
DHCP Server DNS Server*
Resolve request (URL to IP)
DNS response (IP)
* DNS Server steps do not apply if you are using a TFTP Server
Chapter 6 Programmability
TFTP or HTTP
Server