Schneider Electric 840 USE 106 0 manual Power-Up, Services, Effects on the Ethernet services

						Ethernet Hot Standby Solution
Power-Up and	The process of powering up affects the status of client/server services. To clarify
Ethernet	what happens during a power-up, the following section describes the power-up
Services	effects on the Ethernet services.
	The following table shows how the status of an NOE service is affected by the Hot
	Standby state.
	HSBY State		Status of NOE Services
			Client Services		Client/	Server Services
					Server
					Services
			I/O Scanner	Global Data	Modbus	FTP	SNMP	HTTP
					Messaging
	Unassigned		Run	Run	Run	Run	Run	Run
	Primary		Run	Run	Run	Run	Run	Run
	Secondary		Stop	Stop	Run	Run	Run	Run
	Offline		Stop	Stop	Run	Run	Run	Run
Hot Standby
	The following steps describe how NOEs coordinate the Hot Standby switchover.
Switchover
	Step	Action
	1	NOE A (installed in a HSBY rack) detects that is local controller changed from
		Primary to Offline.
	2	NOE A changes its HSBY state from Primary to Offline with the same Ethernet
		services running, starts its watch-dog timer (with 500 ms timeout setting), and
		expects from its peer NOE an UDP request to swap the IP Address.
	3	NOE B (installed in peer HSBY rack) detects that its local controller changed
		state from Secondary to Primary.
	4	NOE B stops all Ethernet services, sends an UDP request to its peer NOE (NOE
		A) for the synchronization of the IP Address swap, starts its watch-dog timer
		(with 500 ms timeout setting), and then waits for an UDP response from its peer
		NOE.
	5	Once NOE A receives the UDP request from NOE B (or after its watch-dog timer
		times out), it stops all Ethernet services, sends an UDP response to NOE B (no
		UDP response is sent to NOE B for watch-dog timeout case), swaps IP Address
		as Secondary, and starts Secondary services.
	6	As soon as NOE B receives the UDP response from NOE A (or after its watch-
		dog timer times out), it swaps IP Addresses and starts Ethernet services as
		Primary.
	7	After NOE A senses that its local controller changes state from Offline to
		Standby, it changes to Secondary accordingly.

840 USE 106 00 January 2003 171