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Authentication
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Provides password-based protection to prevent unauthorized access to an OSPF area. This secures the routing updates exchanged
within that area.
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Route summarization
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Consolidates multiple advertised network addresses into a single, summary route. This reduces the number of entries in routing
tables and the amount of routing information exchanged.
If network numbers are contiguous, an Area Border Router (ABR) can be configured using the area
range router configuration command to advertise a single summary route that encompasses all networks within that range to other
areas.
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Route summarization (for redistributed routes)
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Reduces the size of the OSPF LSDB and routing tables when external routes (from other protocols) are redistributed into OSPF.
Instead of advertising each redistributed route individually as an external LSA (Type 5), the summary-address router configuration command allows you to consolidate multiple contiguous redistributed routes into a single summary route.
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Virtual links
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Maintains backbone continuity in OSPF when a non-backbone area separates a standard area from Area 0, or when Area 0 itself
is segmented.
Use the area
area-id
virtual-link
router-id command to configure a virtual link. This establishes a logical connection between two ABRs through a non-backbone (transit)
area, effectively extending the backbone.
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Domain Name Server (DNS) names in display
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Enhances readability and ease of identification in OSPF show command outputs.
Allows OSPF displays to show router DNS names instead of just their Router IDs or Neighbor IDs, making it simpler for administrators
to identify specific devices.
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Default metrics (cost calculation)
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Determines the "cost" of a link, which OSPF uses to calculate the shortest path.
OSPF calculates the cost of an interface based on its bandwidth using the formula: cost = reference_bandwidth / interface_bandwidth
The default reference bandwidth is 100 Mbps.
For high-bandwidth links (e.g., Gigabit Ethernet), the reference bandwidth can be increased to allow OSPF to differentiate
costs more accurately.
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Administrative distance
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Rates the trustworthiness of routing information learned from different sources.
An integer value between 0 and 255, where a lower value indicates higher trustworthiness. OSPF uses different default administrative
distances for intra-area, inter-area, and external routes. These values can be changed by the administrator.
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Passive interfaces
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Prevents OSPF from sending Hello packets out of a specific interface, typically used on interfaces connected to end-user segments
where no OSPF neighbors are expected.
Once an interface is configured as passive, OSPF stops forming adjacencies on that segment. However, the network connected
to the interface can still be advertised by OSPF.
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Route calculation timers
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Controls the timing of OSPF's SPF algorithm calculations.
Allows configuration of a delay time between a topology change and the start of the SPF calculation, and a hold time between
consecutive SPF calculations. This helps to prevent excessive CPU utilization during periods of network instability.
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Log neighbor changes
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Provides real-time visibility into OSPF neighbor state transitions.
Configure the OSPF-enabled switch to send a syslog message whenever an OSPF neighbor’s state changes, for example, from Down
to Full, or Full to Down. This feature aids network monitoring and troubleshooting.
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