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Web OS 10.0 Application Guide
What Happens When a Switch Fails
Assume that the user performing an e-commerce transaction has selected a number of items
and placed them in the shopping cart. The user has already established a persistent session on
the top server in
At this time, the active switch fails. With stateful failover, the following sequence of events
occurs:
1.
The backup switch (Switch 2) becomes active.
2.
The incoming request is redirected to Switch 2.
3.
When the user clicks Submit again, the request is forwarded to the correct server.
Even though Switch 1 has failed, the stateful failover feature prevents the client from having to
re-establish a secure session. The server that stores the secure session now returns a response
to the client via Switch 2.
Clients
Figure 11-14 Stateful Failover Example when the Master Switch Fails
n
284
Chapter 11: High Availability
Figure
11-14. The user then clicks the Submit button to purchase the items.
Web Switch 1
Failed
Internet
Router
Traffic is redirected
to Switch 2
Web Switch 2
Active
Servers
Layer 2
Switch
IP: A
IP: B
212777-A, February 2002
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