Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 67)

The dest-ip-addr is the route destination. The dest-mask is the network mask for the route destination IP
address. Alternatively, you can specify the network mask information by entering a forward slash
followed by the number of bits in the network mask. For example, you can enter 10.0.0.0 255.255.255.0
as 10.0.0.0/.24.
The next-hop-ip-addr is the IP address of the next-hop router (gateway) for the route.
If you do not want to specify a next-hop IP address, you can instead specify a port or interface number
on the . The num parameter is a virtual interface number. If you instead specify an Ethernet port, the
portnum is the port number (including the slot number, if you are configuring a Layer 3 switch). In this
case, the Layer 3 switch forwards packets destined for the static route destination network to the
specified Layer 3 switch interface. Conceptually, this feature makes the destination network like a
directly connected network, associated with a specific Layer 3 switch interface.
NOTE
The port or virtual interface you use for the static route 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 through 16. The default is 1.
NOTE
If you specify 16, RIP considers the metric to be infinite and thus also considers the route to be
unreachable.
The distancenum parameter specifies the administrative distance of the route. When comparing
otherwise equal routes to a destination, the Layer 3 switch 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 Layer 3 switch 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 Layer 3 switch 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 Layer 3 switch
receives a packet destined for the address, the Layer 3 switch 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.
device(config)# ip route 10.157.22.0 255.255.255.0 null0
device(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 ]
Configuring a "Null" route
FastIron Ethernet Switch Layer 3 Routing Configuration Guide 67
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