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Web OS 10.0 Application Guide
All of the above issues can be addressed by adding an Alteon Web switch with SLB software.
n
Reliability is increased by providing multiple paths from the clients to the Web switch and
by accessing a pool of servers with identical content. If one server fails, the others can take
up the additional load.
n
Performance is improved by balancing the Web request load across multiple servers. More
servers can be added at any time to increase processing power.
n
For ease of maintenance, servers can be added or removed dynamically, without interrupt-
ing shared services.
Network Topology Requirements
When deploying SLB, there are a few key aspects to consider:
n
In standard SLB, all client requests to a virtual server IP address and all responses from the
real servers must pass through the switch, as shown in
the client and the real servers that does not pass through the switch, the Web switch can be
configured to proxy requests in order to guarantee that responses use the correct path (see
"Proxy IP Addresses" on page
Clients
Figure 6-4 SLB Client/Server Traffic Routing
n
Identical content must be available to each server in the same pool. Either of these meth-
ods can be used:
o
o
n
122
Chapter 6: Server Load Balancing
Internet
Router
Switch
Alternate path is not valid with
Layer 4 services. IP proxy
addresses must be used on the
Alteon Web switch
Static applications and data are duplicated on each real server in the pool.
Each real server in the pool has access to the same data through use of a shared file
system or back-end database server.
Figure
136).
Router
Web
Switch
Switch
6-4. If there is a path between
NFS Server
Server Pool #1
Server Pool #2
212777-A, February 2002
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