Brocade Virtual ADX Switch and Router Guide (Supporting ADX v03.1.00) - Manual (Page 85)

Brocade Virtual ADX Switch and Router Guide 71
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Configuring IP parameters
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NOTE
The port or virtual interface you use for the static route’s next hop must have at least one IP address
configured on it. The address does not need to be in the same subnet as the destination network.
The metric parameter can be a number from 1 – 16. The default is 1.
The distance num parameter specifies the administrative distance of the route. When comparing
otherwise equal routes to a destination, the Virtual ADX prefers lower administrative distances over
higher ones, so make sure you use a low value for your default route. The default is 1.
NOTE
The Virtual ADX will replace the static route if the it receives a route with a lower administrative
distance.
NOTE
You can also assign the default router as the destination by entering 0.0.0.0 0.0.0.0 xxx.xxx.xxx.xxx.
Configuring a “Null” route
You can configure the Virtual ADX to drop IP packets to a specific network or host address by
configuring a “null” (sometimes called “null0”) static route for the address. When the Virtual ADX
receives a packet destined for the address, the Virtual ADX drops the packet instead of forwarding
it.
To configure a null static route, use the following CLI method.
To configure a null static route to drop packets destined for network 10.157.22.x, enter the
following commands.
Virtual ADX(config)# ip route 10.157.22.0 255.255.255.0 null0
Virtual ADX(config)# write memory
Syntax: ip route ip-addr ip-mask null0 [metric] [distance num]
or
Syntax: ip route ip-addr/mask-bits null0 [metric] [distance num]
To display the maximum value for your device, enter the show default values command. The
maximum number of static IP routes the system can hold is listed in the ip-static-route row in the
System Parameters section of the display. To change the maximum value, use the system-max
ip-static-route num command at the global CONFIG level.
The ip-addr parameter specifies the network or host address. The Virtual ADX will drop packets that
contain this address in the destination field instead of forwarding them.
The ip-mask parameter specifies the network mask. Ones are significant bits and zeros allow any
value. For example, the mask 255.255.255.0 matches on all hosts within the Class C subnet
address specified by ip-addr. Alternatively, you can specify the number of bits in the network mask.
For example, you can enter 10.157.22.0/24 instead of 10.157.22.0 255.255.255.0.
The null0 parameter indicates that this is a null route. You must specify this parameter to make this
a null route.
The metric parameter adds a cost to the route. You can specify from 1 – 16. The default is 1.
The distance num parameter configures the administrative distance for the route. You can specify a
value from 1 – 255. The default is 1. The value 255 makes the route unusable.