Dell 53-1002116-01 manual Recursive IP static routes, Floating IP static routes

Configuring IP static routes 4

Recursive IP static routes

In a recursive IP static route, only the next hop is specified. The output interface is derived from the next hop. A recursive IP static route is valid (that is, it is a candidate for insertion in the routing table) only when the specified next hop resolves, either directly or indirectly, to a valid output interface, provided the route does not self-recurse, and the recursion depth does not exceed the maximum IPv4 forwarding recursion depth. Fabric OS v6.3.1_cee supports one level of recursion. Beyond this level of recursion the routes are held as inactive routes.

Dell does not recommend manually configuring a self-recursive IP static route, although it is not prohibited. However, a recursive IP static route that has been inserted in the routing table may become self-recursive as a result of some transient change in the network learned through a dynamic routing protocol. If this occurs, the fact that the IP static route has become self-recursive is detected and is removed from the routing table, although not from the configuration. A subsequent network change may cause the IP static route to no longer be self-recursive, in which case it is reinserted in the routing table.

The following example specifies that all destinations with address prefix 1.1.1.1/32 are reachable via the host with address 2.2.2.2.

switch(config)#ip route 1.1.1.1/32 2.2.2.2

Floating IP static routes

Floating IP static routes act as a alternative path to dynamic routes learned through configured routing protocols. A floating IP static route is configured with a higher administrative distance than the dynamic routing protocol. As a result, the dynamic route learned through the routing protocol is always used in preference to the floating IP static route. If the dynamic route learned through the routing protocol is lost, the floating IP static route is used in its place.

A floating IP static route must be configured with an administrative distance that is greater than the administrative distance of the dynamic routing protocol, because routes with smaller administrative distances are preferred. For example, if your Open Shortest Path First (OSPF) protocol is configured with an administrative distance of 120, specify an administrative distance greater than 120 for your floating IP static route.

The following example defines a floating IP static route that shows all destinations with address prefix 1.1.1.1/32 are reachable through internal 10 Gbps interface 0/1:

switch(config)#ip route 1.1.1.1/32 intengigabitethernet 0/1 121

Displaying and clearing IP static routes

To display the current IP routing information and clear the assigned settings, perform the following procedure from EXEC mode.

1. Display a summary of the IP routing table.

switch>show ip route summary		Subnets	Overhead	Memory (bytes)
Route Source	Networks
connected	0	1	64	160
static	1	1	128	320
internal	1	2	192	1180
Total	2			1660

Dell Converged Enhanced Ethernet Administrator’s Guide	29
53-1002116-01