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Enhancements
Release R.11.14 Enhancements
Possible Scenarios for Updating the Configuration File
The following table shows various network configurations and how Option 66 is handled.
Operating Notes
Replacing the Existing Configuration File: After the DHCP client downloads the configuration
file, the switch compares the contents of that file with the existing configuration file. If the content
is different, the new configuration file replaces the existing file and the switch reboots.
Option 67 and the Configuration File Name: Option 67 includes the name of the configuration
file. If the DHCPACK contains this option, it overrides the default name for the configuration file
(switch.cfg)
Global DHCP Parameters: Global parameters are processed only if received on the primary VLAN.
Best Offer: The “Best Offer” is the best DHCP or BootP offer sent by the DHCP server in response
to the DHCPREQUEST sent by the switch. The criteria for selecting the “Best Offer” are:
Scenario Behavior
Single Server serving Multiple VLANs • Each DHCP-enabled VLAN interface initiates DHCPDISCOVER
message, receives DHCPOFFER from the server, and send
DHCPREQUEST to obtain the offered parameters.
• If multiple interfaces send DHCPREQUESTs, it’s possible that more
than one DHCPACK is returned with a valid Option 66.
• Evaluating and updating the configuration file occurs only on the
primary VLAN.
• Option 66 is ignored by any interfaces not belonging to the primary
VLAN.
Multiple Servers serving a Single VLAN • Each DHCP-enabled VLAN interface initiates one DHCPDISCOVER
and receives one or more DHCPOFFER messages.
• Each interface accepts the best offer.
• Option 66 is processed only for the interface belonging to the primary
VLAN.
Multiple Servers serving Multiple VLANs • Each DHCP-enabled VLAN interface initiates DHCPDISCOVER and
receives one or more DHCPOFFER messages.
• Each interface accepts the best offer.
• Option 66 is processed only for the interface belonging to the primary
VLAN.
Multi-homed Server serving Multiple VLANs • The switch perceives the multi-homed server as multiple separate
servers.
• Each DHCP-enabled VLAN interface initiates DHCPDISCOVER and
receives one DHCPOFFER message.
• Each interface accepts the offer.
• Option 66 is processed only for the interface belonging to the primary
VLAN.