Dell PowerConnect B-FCXs, Configuration Manual

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826 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring IP parameters – Layer 3 Switches
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Figure 129 shows an example of two static routes configured for the same destination network. In
this example, one of the routes is a standard static route and has a metric of 1. The other static
route is a null route and has a higher metric than the standard static route. The Layer 3 Switch
always prefers the static route with the lower metric. In this example, the Layer 3 Switch always
uses the standard static route for traffic to destination network 192.168.7.0/24, unless that route
becomes unavailable, in which case the Layer 3 Switch sends traffic to the null route instead.
FIGURE 129 Standard and null static routes to the same destination network
Figure 130 shows another example of two static routes. In this example, a standard static route
and an interface-based static route are configured for destination network 192.168.6.0/24. The
interface-based static route has a lower metric than the standard static route. As a result, the Layer
3 Switch always prefers the interface-based route when the route is available. However, if the
interface-based route becomes unavailable, the Layer 3 Switch still forwards the traffic toward the
destination using an alternate route through gateway 192.168.8.11/24.
X
Two s t a tic ro u te s to 192.168.7.0/24:
--St a nd a rd s t a tic ro u te thro u gh
g a tew a y 192.168.6.157, with metric 1
--N u ll ro u te, with metric 2
Switch A
Switch A
Switch B
Switch B
192.168.6.188/24 192.168.6.157/24 192.168.7.7/24
192.168.7.69/24
When s t a nd a rd s t a tic ro u te
i s good, Switch A us e s th a t
ro u te.
192.168.6.188/24
192.168.6.157/24
192.168.7.7/24
192.168.7.69/24
If s t a nd a rd s t a tic ro u te i s
u n a v a il a ble, Switch A us e s
the n u ll ro u te (in effect dropping
in s te a d of forw a rding the p a cket s ).
N u ll