Question

What is the purpose of OSPF LSR (Link-State Request)?

a) To send LSAs to a neighbor
b) To request specific LSAs from a neighbor
c) To exchange a list of known LSAs between neighbors
d) To update the OSPF routing table

Answer 1

OSPF LSR is used to request specific, potentially newer LSAs from a neighboring router to ensure the local router's link-state database is synchronized with other routers in the network for accurate routing.

Step-by-step explanation:

The purpose of OSPF (Open Shortest Path First) LSR (Link-State Request) is b) To request specific LSAs from a neighbor. LSR messages are used by OSPF routers to request the most up-to-date link-state advertisements (LSAs) from other routers in the network. When an OSPF router receives an LSA header but does not have the corresponding LSA in its database or has an older version, it sends an LSR to request the complete, updated LSA from its neighbor.

LSRs ensure that a router's link-state database is synchronized with its OSPF neighbors, which is essential for the proper operation of OSPF. The accurate and timely exchange of LSAs through LSRs and other OSPF message types enables OSPF to effectively calculate the shortest path to each network destination, and thus update the routing table with the best routes.