Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 155)

NOTE
If you specify 16, RIP considers the metric to be infinite and thus also considers the route to be
unreachable.
The tag num parameter specifies the tag value of the route. Possible values: 0 - 4294967295. Default:
0.
The distance num parameter specifies the administrative distance of the route. When comparing
otherwise equal routes to a destination, the Brocade device prefers lower administrative distances over
higher ones, so make sure you use a low value for your default route. Possible values: 1 - 255. Default:
1.
NOTE
The Brocade device will replace the static route if it receives a route with a lower administrative
distance.
The name string parameter specifies the name assigned to a route. The static route name is descriptive
and an optional feature. It does not affect the selection of static routes.
Configuring a "null" route
You can configure the Brocade device 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 Brocade device
receives a packet destined for the address, the Brocade device drops the packet instead of forwarding
it.
To configure a null static route to drop packets destined for network 209.157.22.x, enter the following
commands.
device(config)# ip route 209.157.22.0 255.255.255.0 null0
device(config)# write memory
Syntax: [no] ip route { ip-addr ip-mask | dest-ip-addr /mask-bits } null0 [ metric ] [ tag num ] [ 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 command at the global CONFIG level.
The ip-addr parameter specifies the network or host address. The Brocade device 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 209.157.22.0/24 instead of 209.157.22.0 255.255.255.0.
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 tag num parameter specifies the tag value of the route. Possible values: 0 - 4294967295. Default:
0.
Configuring a "null" route
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