Filter
Top Products
Ethernet Hot Standby Solution
164
840 USE 106 00 January 2003
Overview of Hot Standby Solution for NOEs
Please Note The Quantum Hot Standby system supports up to four NOE 771 Ethernet
connections. For a more detailed description of the physical set up of a Hot Standby
system, refer to the
Quantum NOE 771 xx Ethernet Modules User Guide
,
840USE11600, Chapter 9, "Hot Standby".
Description of
the Hot Standby
Solution
The Hot Standby solution provides bumpless transfer of I/O using remote I/O. The
NOE Hot Standby support now allows automation IP Address change. Both
controllers are configured identically. One controller is the Primary NOE; the other
controller, the Secondary NOE. In case of a failure, the controllers switchover and
the system recovers quickly.
The NOEs coordinate the swapping of IP addresses. After closing both the client
and the server connections, each NOE sends a swap UDP message to its peer
NOE. The sending NOE then waits a specified timeout (500 ms) for the peer swap
of UDP messages. Either after receiving the messages or after a timeout, the NOE
changes its IP address.
The NOE waits for either a change in the controller’s Hot Standby state or the swap
of UDP messages. Then the NOE performs one of two Hot Standby actions.
If the NOE:
1. Detects that the new Hot Standby state is either primary or standby:
The NOE changes the IP address
2. Receives a swap UDP message:
The NOE transmits a Swap UDP message and swaps the IP address
Note: NOEs must communicate with each other in order to swap IP Addresses.
Schneider Electric recommends that you connect the primary and Secondary
NOEs to the same switch because
Communication failures between the NOEs increases the time to swap
Connecting two NOEs to the same switch, minimizes the probability of a
communication failure
Note: Schneider Electric recommends that a switch is used to connect the NOEs
to each other or to the network. Schneider Electric offers switches; please contact
a local sales office for more information.