OSPF is a connection state steering convention that is utilized to track down the best way between the source and the objective. The SPF calculation is utilized to decide the best way. OSPF empowered switches trade LSAs to refresh and keep up with LSDBs. LSAs go about as data set records and give explicit OSPF network subtleties. As of now, 11 distinct sorts of LSAs are depicted in RFCs for OSPF. The initial five kinds of LSA are significant for the execution of multiarea OSPF.

  • LSA Type 1: Router LSA
  • LSA Type 2: Network LSA
  • LSA Type 3: Summary LSA
  • LSA Type 4: ASBR Summary LSA
  • LSA Type 5: ASBR External LSA
  • LSA Type 6: Group Membership LSA
  • LSA Type 7: Not So Stubby Area (NSSA) External LSA
  • LSA Type 8: External Attributes LSA (OSPFv2)/Link-Local LSA (OSPFv3)
  • LSA Type 9: Link Scope Opaque (OSPFv2)/Intra Area Prefix LSA (OSPFv3)
  • LSA Type 10: Area Scope Opaque LSA
  • LSA Type 11: AS (Autonomous System) Scope Opaque LSA


Type 1 LSA is produced by each switch for each connection that has a place with an area. They are overwhelmed uniquely inside an area to which they have a place. Interface ID of this LSA is the Router ID of the switch that produced it. In the sort 1 LSA switches publicize their straightforwardly associated OSPF-empowered connections and forward their organization data to OSPF neighbors. The LSA contains the data of straightforwardly associated interfaces, connect types, and connection states.

ABRs in this manner promote the organizations gained from the sort 1 LSAs to different regions as type 3 LSAs. The sort 1 LSA interface ID is recognized by the Router ID of the starting switch. The figure 1 beneath shows the OSPF LSA Type 1. Bothe Routers are the individual from Area-x and x is an OSPF region. The LSAs are trade inside the area.


The assigned switches sent sort 2 LSAs to any remaining switches present in a similar region (multiaccess and non-broadcast multiaccess (NBMA). The sort 2 LSAs contain the DR and BDR IP data and furthermore the condition of different switches that are essential for a similar organization.

Both LSA types 1 and type 2 be available in all areas and are never overflowed outside of the area. The connection state ID for an organization LSA is the IP interface address of the DR that publicizes it.


Region Border Routers (ABRs) utilized sort 3 LSAs to promote networks from different regions. ABRs gather type 1 LSAs in the LSDB. Whenever OSPF region becomes united, the ABR switches make a sort 3 LSA for every one of its learned OSPF organizations and infuse the LSA to the spine region. Subsequently, an ABR with numerous OSPF courses should make type 3 LSAs for each organization.

The LSA incorporates the IP data and Router I’d of ABR that is publicizing these LSA. It publicized organizations from a region to the other regions in AS. Type 3 LSA is overflowed to different regions all through the organization and increment OSPF adaptability with utilization of rundown prefixes.


Type 4 LSAs (Summary ASBR LSA) are like sort 3 LSAs with the exception of the kind 4 LSAs are created from the independent framework line switch (ASBR) rather than Area Border Router (ABRs). Type 4 and type 5 LSAs are utilized together to perceive an ASBR and publicize outside networks into an OSPF steering space.

An ABR creates type 4 outline LSA when an ASBR exists inside an area. A sort 4 LSA recognizes the ASBR and gives a course to it. All traffic bound to an ASBR requires directing table data of the ASBR that started the outside courses.


Independent framework outside LSAs are produced by ASBRs and contain courses to networks that are outer to the current independent framework (AS). Connect state ID is network number promoted in LSA. Type 5 LSAs are overflowed to the whole independent framework. It isn’t overflowed into any stub regions.

Type 5 portrays courses that are rearranged into the area. These are courses are viewed as outside courses and add into the steering table with “OE1” or “OE2”. We have effectively talked about the OE1 and OE2 courses in the sorts of OSPF switches.

The distinction in these is the way the expense is determined for a course. A regular illustration of a Type 5 LSA would be a default course (web) as displayed in figure 5 beneath. The outer course/prefix is rearranged into the OSPF network by the ASBR (R1) and seen as O E1 or O E2 passages in other OSPF switches steering tables.


It is a Group Membership LSA intended for Multicast OSPF (MOSPF), a convention that upholds multicast steering through OSPF. Cisco isn’t supporting MOSPF and nor it is broadly utilized. So it very well may be skip since it’s not being utilized.


Type 7 LSAs are just found inside a not so squat region where type 5 outside LSAs doesn’t permit. The sort 7 LSAs is created by the ASBR inside the NSSA to depict outside courses. It goes about as a veil for Type 5 LSA bundles to permit them to travel through these extraordinary regions and arrive at the ABR that can decipher LSA Type 7 parcels back to LSA Type 5 bundles. Type 7 outer LSA conveys a similar data however isn’t impeded inside the NSSA region.

At the point when type 7 LSA leaves the NSSA, it is meant a sort 5 LSA by the ABR. These courses read refreshed from type 7 LSA appear in the steering table with the N1 and N2 assignment.


This type is utilized to work with BGP. LSA Type 8 parcels in OSPFv2 (IPv4) are called External Attribute LSAs and are utilized to move BGP ascribes all through an OSPF organization. This element isn’t upheld by most the switches. With OSPFv3, This type is reclassified to convey IPv6 data all through the OSPF organization.

LSA Type 9

This type is ordinarily alluded to as a connection state murky LSA. For OSPFv3 it’s re-imagined to deal with a correspondence prefix for an extraordinary region type called Stub Area. As connection nearby ads, they are not overflowed outside of a solitary connect to another gadget.


LSA type 10 (OSPF Area Scope Opaque LSA )is utilized to flood OSPF data through other region switches regardless of whether these switches interaction this data to broaden OSPF usefulness.


Type 11 (OSPF As Scope Opaque LSA) bundles do similar occupation as Type 10 parcels however are not overflowed into exceptional region types like Stub regions.