What is down state in OSPF?
The Down State is the first OSPF neighbor state and means no Hello packets have been received from a neighbor.
What happens in OSPF when a link goes down?
When the link is reported down to OSPF, it will generate the LSA. and flood it to all its neighbors. The routers that receive the new LSA will have to run SPF to calculate the new topology. This is delayed by 5 seconds unless the default timer has been modified.
What are the states in OSPF?
OSPF has eight neighbor states: Down, Attempt, Init, 2-way, Exstart, Exchange, Loading, and Full. Down: indicates that a router has not received any Hello packets from its neighbors within a neighbor dead interval.
What happens when a link fails?
Link failures results in invalid routes and unreachable routes within Ethernet based networks. Invalid routes record the duration of the each route containing failed link and summation of invalid route time. Unreachable routes records the total number of routes that are failed during network segregation.
Why is OSPF stuck in INIT state?
OSPF Neighbor Stuck in INIT ‚ Cause: The frame-relay map/dialer-map Statement on One Side Is Missing the broadcast Keyword. OSPF uses a multicast address of 224.0. 0.5 to send and receive OSPF Hellos. If one side is incapable of sending or receiving Hellos, the OSPF neighbor will be stuck in the INIT state.
What causes OSPF to flap?
A fault on an optical fiber or optical module causes frequent Up/Down state changes on the link between the devices. The unstable link results in OSPF neighbor relationship flapping.
What is OSPF link state concept?
The OSPF protocol is a link-state routing protocol, which means that the routers exchange topology information with their nearest neighbors. The topology information is flooded throughout the AS, so that every router within the AS has a complete picture of the topology of the AS.
Is OSPF link state or distance vector?
OSPF is not a distance-vector protocol like RIP, but a link-state protocol with a set of metrics that can be used to reflect much more about a network than just the number of routers encountered between source and destination. In OSPF, a router attempts to route based on the “state of the links.”