BigIron RX Series Configuration Guide 19953-1002253-01Configuring forwarding parameters 7Static route typesYou can configure the following types of static IP routes:• Standard – the static route consists of the destination network address and network mask,and the IP address of the next-hop gateway. You can configure multiple standard static routeswith the same metric for load sharing or with different metrics to provide a primary route andbackup routes.• Interface-based – the static route consists of the destination network address and networkmask, and the device interface through which you want the device to send traffic for the route.Typically, this type of static route is for directly attached destination networks.• Null – the static route consists of the destination network address and network mask, and the“null0” parameter. Typically, the null route is configured as a backup route for discarding trafficif the primary route is unavailable.Static IP route parametersWhen you configure a static IP route, you must specify the following parameters:• The IP address and network mask for the route’s destination network.• The route’s path, which can be one of the following:• The IP address of a next-hop gateway• An Ethernet port• A virtual interface (a routing interface used by VLANs for routing Layer 3 protocol trafficamong one another)• A “null” interface. The device drops traffic forwarded to the null interface.The following parameters are optional:• The route’s metric – The value the device uses when comparing this route to other routes inthe IP route table to the same destination. The metric applies only to routes that the device hasalready placed in the IP route table. The default metric for static IP routes is 1.• The route’s administrative distance – The value that the device uses to compare this route withroutes from other route sources to the same destination before placing a route in the IP routetable. This parameter does not apply to routes that are already in the IP route table. The defaultadministrative distance for static IP routes is 1.The default metric and administrative distance values ensure that the device always prefers staticIP routes over routes from other sources to the same destination.Multiple static routes to the same destination provide load sharingand redundancyYou can add multiple static routes for the same destination network to provide one or more of thefollowing benefits:• IP load balancing – When you add multiple IP static routes for the same destination to differentnext-hop gateways, and the routes each have the same metric and administrative distance, thedevice can load balance traffic to the routes’ destination. For information about IP loadbalancing, refer to “Configuring IP load sharing” on page 209.
