Home Technology Introduction to the Different OSPF States and Process – Exchange routing information Using LSAs!

Introduction to the Different OSPF States and Process – Exchange routing information Using LSAs!

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When an OSPF router is initially linked to a network it completes the next generic link-condition routing OSPF process and will get the condition of convergence through altering different states. Before discussing OSPF states, I will discuss OSPF Process.


Create adjacencies with neighbours

OSPF configured router form adjacencies using their neighbours before share information with this neighbour. It transmits Hello packets out all OSPF-enabled interfaces to solve connected OSPF neighbours on individuals interfaces. If your neighbour is located, it tries to establish neighbour adjacency with this neighbour.


Exchange routing information Using LSAs

When adjacencies are in place between neighbours, they exchange link-condition advertisements (LSAs) with every other’s that contains the condition and price of every directly connected link. Routers ton their LSAs to adjacent neighbours and adjacent neighbours get the LSAs and ton it immediately with other directly connected neighbours until all routers in the region have LSAs.


Build the topology table

After finding the LSAs, OSPF-enabled routers build the topology table in line with the received LSAs. It holds all the details concerning the topology from the network. All routers in the region must have a similar information within the topology table.


Execute the SPF formula

Rouers then execute the SPF formula. The SPF formula produces the SPF tree.


Calculate the very best routes

After allowing the SPF tree the router inserts the very best path in to the routing table. Routing decisions are created in line with the records within the routing table.


Achieve convergence

This is actually the real OSPF condition from the router that is needed for that actual operation from the routing. The OSPF progresses through different OSPF states while make an effort to achieve convergence. The figure below illustrates the various OSPF states progress:



  • This may be the OSPF condition once the router is lower.
  • When it’s Switch On it transmits Hello Packet
  • If the router is exciting to init condition.


Init condition

  • The condition is yet another OSPF condition once the router just received the hello packet in the neighbours that contains the delivering router ID.
  • Transition to 2-Way Condition


Two-Way condition

  • In the OSPF condition, the path elect a DR or BDR on Ethernet links
  • Transition to ExStart Condition


ExStart condition

  • Negotiate master / Slave relationship, also DBD packet sequence number
  • The master initiates the DBD packet exchange


Exchange condition

  • In this condition Routers Exchange DBD Packets.
  • In situation of more dependence on information router transit to loading condition, otherwise, the transition fully condition.


Loading condition

  • To gain in information router uses LSRs and LSUs.
  • The route is processed while using SPF formula
  • Transition to full condition


Full condition

  • This may be the actual condition that is needed also termed as a converged condition.

[qsm quiz=14]



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