Schneider Electric 840 USE 106 0 Address, Assignment, Offline Mode at Power-up Sequence table

Ethernet Hot Standby Solution

Power-Up and IP The process of powering up affects the NOE’s IP Address assignment. To clarify

Address	what happens during a power-up, the following two sections describe the power-up
Assignment	effects on IP Address assignment and Ethernet services.

An NOE obtains its IP Address assignment at power-up as follows:

If the HSBY state is ...	Then the IP Address assigned is ...
Unassigned	Configured IP Address
Primary	Configured IP Address
Secondary	Configured IP Address + 1
Unassigned to Offline	See the Offline Mode at Power-up Sequence table following

If two NOEs power-up simultaneously, a "resolution algorithm" determines the Primary NOE, and after determining the Primary NOE, the "resolution algorithm" assigns the configured IP Address to the Primary NOE and then assigns the configured IP Address + 1 to the Secondary NOE.

Offline Mode at Power-up Sequence table:

Offline Mode at Power-up Sequence	Result
Controller A powers-up before controller B	IP Address of controller A is configured IP
	lAddress
	IP Address of controller B is the configured
	IP Address + 1
Both controller A and controller B power-up	The resolution algorithm will assign controller A
a the same time	the configured IP address and will assign
	controller B the configured IP address + 1.

The NOE performs a "duplicate IP" test by issuing an ARP request to the configured IP Address. If a response is received within 3 seconds, the IP Address remains at the Default IP and blinks a diagnostic code.

If no IP configuration exists, the NOE remains in standalone mode, and the IP Address must be obtained from either a BOOTP server or from a MAC address.

170 840 USE 106 00 January 2003