Coyote Point Systems E350GX, Installation And Administration Manual

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Chapter 4: Equalizer Network Configuration
78 Equalizer Installation and Administration Guide
Configuring Servers on Your Network
Configuring Routing on Servers
In configurations where the cluster
spoof
option is enabled, you should configure your servers so that Equalizer
gateways the packets the servers send to clients. In most cases, the easiest way to do this is to specify an IP address
on Equalizer as the server default gateway in its routing tables. If you do not adjust the routing on your servers when
the
spoof
option is enabled, servers will not route responses throught Equalizer and clients receiving such responses
directly from servers will drop the responses and the client connection will time out.
Direct Server Return (DSR) configurations, however, are an exception to this rule. In DSR configurations, client
requests coming through Equalizer are routed to servers, which then respond directly back to the clients without
going through Equalizer. Therefore, servers in a DSR configuration typically have a default gateway other than
Equalizer.
Otherwise, in non-DSR clusters with
spoof
enabled, you should use one of the following Equalizer addresses as the
default gateway on the servers in the cluster:
• If the servers are connected to a single (standalone) Equalizer , the default gateway IP address that you
should use on the server is Equalizer’s IP address on the VLAN associated with the Equalizer front-panel
port to which the server is connected.
• If the servers are connected to two Equalizers in a failover configuration , the default gateway IP
address that you should use on the server is always Equalizer’s failover IP address on the VLAN associated
with the Equalizer front-panel port to which the server is connected.
The commands or utilities that you use to configure routing on a server depends on the server’s operating system,
but usually involves some form of the
route
command; check your server’s operating system documentation. To
verify that you have configured a server’s routing correctly, trace the route from the server to a destination address
outside the internal network to ensure that Equalizer gets used as a gateway. On UNIX systems, use the
traceroute
utility; on Windows, use
tracert
.
Configure routing on each server from the server’s system console, not through a telnet session. This will avoid any
disconnects that might otherwise occur as you adjust the network settings on the server.
Server Configuration Constraints
When configuring servers into clusters on Equalizer, you must observe the following constraiunts:
• In order for Equalizer to initialize properly when it boots, there must be at least one running server that is
responding to Equalizer probes, and there must be no Layer 3 devices (e.g., such as a router) between that
server and Equalizer.
• Servers can be located behind routers, but we do not recommend or support such configurations. Various
Equalizer subsystems (such as the health check probing subsystem) depend on reliable communication
between Equalizer and the servers behind it, and the latency introduced by Layer 3 devices such as routers
can, for example, result in connection timeouts even when the server is available.
• If you do require remote servers in your clusters, you must be very careful to configure network routes that
allow Equalizer and the server to communicate.
An example of a configuration with both directly connected servers and remotely accessible servers is illustrated in
the diagram below.