How does ospf calculate cost

Skip to main content Skip to header right navigation Skip to site footer. OSPF cost calculation. How does OSPF work out the interface cost? This is set in the ospf process Router1 config router ospf 1 Router1 config-router auto-cost reference-bandwidth? Static neighbor entries configuration. Limiting the number of hops an IPv6 packet can traverse. IPv6 source routing security enhancements. TCAM space configuration. Displaying IPv6 global information. Displaying the IPv6 local router information.

Clearing global IPv6 information. IPv4 Static Routing. Overview of static routing. Static route states follow port states. Configuring a basic IP static route. Adding metrics to a static route. Naming an IP static route. Removing a name or a static route. Configuring a physical interface as next hop. Configuring a virtual interface as next hop. Configuring a tunnel as next hop. Configuring a static route for use with a route map.

Configuring a null route. Configuring a default static route. Resolving a static route using other static routes. Resolving the next hop through a protocol. Configuring load sharing and redundancy. Determining maximum static routes. Displaying IPv4 static routes. IPv6 Static Routing. Configuring a basic IPv6 static route. Removing an IPv6 static route.

Configuring an interface as next hop. Adding metrics to an IPv6 static route. Resolving the IPv6 static route through a protocol. Adding an IPv6 static route tag for use with route-maps. IPv6 multicast static routes. Displaying information on IPv6 static routes. RIP overview. Overview of RIP route learning and advertising parameters. Redistribution of routes into RIP. Using prefix lists and route maps to filter RIP routes.

Enabling RIP and configuring global parameters. Configuring RIP interfaces. Displaying RIP Information. RIPng Overview. RIPng configuration overview. Enabling RIPng and configuring global parameters.

Enabling and configuring RIPng interfaces. Displaying RIPng information. OSPFv2 overview. Autonomous System. OSPFv2 components and roles. Maximum limit overload processing. Enabling OSPFv2. Backbone area. Assigning OSPFv2 areas. Area range. Assigning an area range. Area types. Stub area and totally stubby area.

Disabling summary LSAs for a stub area. Not-so-stubby area NSSA. Configuring an NSSA. Configuring a summary-address for the NSSA. Assigning interfaces to an area. Link state advertisements. Virtual links. Configuring virtual links. Default route origination. External route summarization. SPF timers. Modifying Shortest Path First timers.

OSPFv2 administrative distance. Re-enabling OSPFv2 graceful restart. Disabling OSPFv2 graceful restart helper. OSPFv2 stub router advertisement. OSPFv2 non-stop routing. Limitations of NSR. Synchronization of critical OSPFv2 elements. Link state database synchronization. LSA delayed acknowledging. LSA syncing and packing.

Neighbor device synchronization. Synchronization limitations. Interface synchronization. Standby module operations. OSPFv2 distribute list. Configuring an OSPFv2 distribution list using route maps. OSPFv2 route redistribution. Redistributing routes into OSPFv2. Load sharing. Interface types to which the reference bandwidth does not apply. Changing the reference bandwidth for the cost on OSPFv2 interfaces.

OSPFv2 authentication. OSPFv2 keychain authentication. OSPFv2 authentication configuration. Configuring plain text authentication on an OSPFv2 interface. Configuring plain text authentication on an OSPFv2 virtual link. Configuring keychain authentication on an OSPFv2 interface. Configuring keychain authentication on an OSPFv2 virtual link. Configuring authentication key activation wait time on an OSPFv2 interface.

Configuring authentication key activation wait time on an OSPFv2 virtual link. Displaying OSPFv2 results. Changing default settings. Disabling and re-enabling OSPFv2 event logging. Understanding the effects of disabling OSPFv2. Disabling OSPFv2. OSPFv3 overview. Configuring the router ID. Enabling OSPFv3. Configuring OSPFv3. OSPFv3 areas. Assigning OSPFv3 areas. Assigning OSPFv3 areas to interfaces.

Configuring a stub area. Not-so-stubby area. Virtual link source address assignment. OSPFv3 route redistribution. Redistributing routes into OSPFv3.

Configuring default external routes. Disabling and re-enabling OSPFv3 event logging. Filtering OSPFv3 routes. Configuring an OSPFv3 distribution list using a route map as input.

Modifying SPF timers. OSPFv3 administrative distance. Configuring administrative distance based on route type. Changing the reference bandwidth for the cost on OSPFv3 interfaces. Setting all OSPFv3 interfaces to the passive state. OSPFv3 graceful restart helper. Disabling OSPFv3 graceful restart helper.

Re-enabling OSPFv3 graceful restart helper. OSPFv3 non-stop routing. OSPFv3 Authentication. OSPFv3 authentication trailer. OSPFv3 keychain authentication. OSPFv3 authentication trailer configuration. Configuring keychain authentication on an OSPFv3 interface. 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.

What is stub area in OSPF? A stub area is an area in which you do not allow advertisements of external routes, which thus reduces the size of the database even more.

Instead, a default summary route 0. How does OSPF prevent loops? Because inter-area OSPF is distance vector, it is vulnerable to routing loops. It avoids loops by mandating a loop-free inter-area topology, in which traffic from one area can only reach another area through area 0.

What is the metric that is used by OSPF? How does OSPF learned routes? Two routers speaking OSPF to each other exchange information about the routes they know about and the cost for them to get there. When many OSPF routers are part of the same network, information about all of the routes in a network are learned by all of the OSPF routers within that network—technically called an area. What is cost in routing protocol?

It stands for the distance between routes. For example, a directly connected route has a cost equal to 0, a static one has cost equal to 1, and so on.