Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 815)

Multi-Service IronWare Switching Configuration Guide 785
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Configuring static routes
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Multiple static routes to the same destination provide load sharing and
redundancy
You can add multiple static routes for the same destination network to provide one or more of the
following benefits:
• IP load balancing – When you add multiple IP static routes for the same destination to different
next-hop gateways, and the routes each have the same metric and administrative distance, the
Brocade device can load balance traffic to the routes’ destination. For information about IP
load balancing, refer to
“Configuring IP load sharing” on page 804.
• Path redundancy – When you add multiple static IP routes for the same destination, but give
the routes different metrics or administrative distances, the Brocade device uses the route
with the lowest administrative distance by default, but uses another route to the same
destination of the first route becomes unavailable.
Refer to the following sections for examples and configuration information:
• “Configuring load balancing and redundancy using multiple static routes to the same
destination”
on page 791
• “Configuring standard static IP routes and interface or null static routes to the same
destination”
on page 792
Static route states follow port states
IP static routes remain in the IP route table only so long as the port or virtual interface used by the
route is available. If the port or virtual routing interface becomes unavailable, the software removes
the static route from the IP route table. If the port or virtual routing interface becomes available
again later, the software adds the route back to the route table.
This feature allows the Brocade device to adjust to changes in network topology. The Brocade
device does not continue trying to use routes on unavailable paths but instead uses routes only
when their paths are available.
Figure 199 shows a network containing a static route. The static route is configured on Router A, as
shown in the CLI following the figure.
FIGURE 199 Example of a static route
The following command configures a static route to 207.95.7.0, using 207.95.6.157 as the
next-hop gateway.
Brocade(config)# ip route 207.95.7.0/24 207.95.6.157
When you configure a static IP route, you specify the destination address for the route and the
next-hop gateway or Brocade device interface through which the Brocade device can reach the
route. The Brocade device adds the route to the IP route table. In this case, Router A knows that
207.95.6.157 is reachable through port 1/2, and also assumes that local interfaces within that
subnet are on the same port. Router A deduces that IP interface 207.95.7.188 is also on port 1/2.