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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
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Chapter38 Configuring IP Unicast Routing Configuring OSPF
•Default Metrics: OSPF calculates the OSPF metric for an interface according to the bandwidth of
the interface. The metric is calculated as ref-bw divided by bandwidth, where ref is 10 by de fau lt,
and bandwidth (bw) is specified by the bandwidth interface configuration command. For multiple
links with high bandwidth, you can specify a larger number to differentiate the cost on those links.
•Administrative distance is a rating of the trustworthiness of a routing information source, an i nteg er
between 0 and 255, with a higher value meaning a lower trust rating. An ad ministrative distance of
255 means the routing information source cannot be trusted at all and should be ignored. OSPF uses
three different administrative distances: routes within an area (interarea), routes to another area
(interarea), and routes from another routing domain learned through redistribution (external) . You
can change any of the distance values.
•Passive interfaces: Because interfaces between two devices on an Ethernet represent only one
network segment, to prevent OSPF from sending hello packets for the sending interface, you must
configure the sending device to be a passive interface. Both devices can iden tify each other through
the hello packet for the receiving interface.
•Route calculation timers: You can configure the delay time between when OSPF receives a topology
change and when it starts the shortest path first (SPF) calculation and the hold time between two
SPF calculations.
•Log neighbor changes: You can configure the router to send a syslog message when an OSPF
neighbor state changes, providing a high-level view of changes in the router.