Chapter 50
| IP Routing Commands
Global Routing Configuration
– 961 –
Command Usage
â—† The FIB contains information required to forward IP traffic. It contains the
interface identifier and next hop information for each reachable destination
network prefix based on the IP routing table. When routing or topology
changes occur in the network, the routing table is updated, and those changes
are immediately reflected in the FIB.
The FIB is distinct from the routing table (or, Routing Information Base), which
holds all routing information received from routing peers. The forwarding
information base contains unique paths only. It does not contain any secondary
paths. A FIB entry consists of the minimum amount of information necessary to
make a forwarding decision on a particular packet. The typical components
within a forwarding information base entry are a network prefix, a router port
identifier, and next hop information.
â—† This command only displays routes which are currently accessible for
forwarding. The router must be able to directly reach the next hop, so the VLAN
interface associated with any dynamic or static route entry must be up. Note
that routes currently not accessible for forwarding, may still be displayed by
using the show ip route database command.
Example
In the following example, note that the entry for RIP displays both the distance and
metric for this route.
Console#show ip route
Codes: C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default
R 10.1.1.0/24 [120/2] via 192.168.1.10, VLAN1, 00:00:14
C 127.0.0.0/8 is directly connected, lo
C 192.168.1.0/24 is directly connected, VLAN1
Console#
show ip route
database
This command displays entries in the Routing Information Base (RIB).
Command Mode
Privileged Exec
Command Usage
The RIB contains all available routes learned through dynamic routing protocols,
directly attached networks, and any additionally configured routes such as static
routes. The RIB contains the set of all available routes from which optimal entries
are selected for use by the Forwarding Information Base (see Command Usage
under the show ip route command).
To Next Page
Loading...
Need help?
General