The cost of an interface is inversely proportional to its bandwidth. A
higher bandwidth indicates a lower cost. By default, Cisco routers calculate the cost of an interface
based on the bandwidth. However, you can force the cost of an interface with the command ip ospf
cost {value} in interface con?¬?guration mode.
If equal-cost paths exist to the same destination, the Cisco implementation of OSPF can keep track
of up to 16 next hops to the same destination in the routing table (which is called load balancing).
By default, the Cisco router supports up to four equal-cost paths to a destination for OSPF. Use
the maximum-paths command under the OSPF router process con?¬?guration mode to set the
number of equal-cost paths in the routing table, as shown in Example 4-8.
Example 4-8 Setting the Number of Equal-Cost Paths in the Routing Table
RouterX(config)#rroouutteerr oossppff 11
RouterX(config-router)#mmaaxxiimmuumm--ppaatthhss ??
<1-16> Number of paths
RouterX(config-router)#mmaaxxiimmuumm--ppaatthhss 33
Network
172.16.0.0
config#
router ospf 100
config-router#
maximum-paths 6
config#
interface range fa0/1 ??“ 6
config-if# ip ospf cost 5
156 Chapter 4: Single-Area OSPF Implementation
You can use the show ip route command to ?¬?nd equal-cost routes.
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