OSPF Simulation - Area Border Router (Interactive, Visual) - Education - Online Education

Q1. What is OSPF ABR?Answer: ABR stands for Area Border Router. It connects area 0 and several other areas.Q2. Why do we need ABR?Answer. When there are too many routers in an OSPF network, flooding Router LSAs becomes a problem: It consumes too much network bandwidth and make LSDB very large. Just think of running 1000 OSPF routers. There will be 1000 Router LSAs to flood. To solve this problem, OSPF segments the network into smaller groups called areas. Now Router LSA flooding is confined to an area. ABR is a router that bridges several groups.Q3. What does ABR do?Answer: It discovers addresses in one group (area) and announces them to routers in other groups. This way, routers don't flood their Router LSAs across area borders but still able to discover network addresses located in other areas and reach them via ABR.Q4. How does ABR announce network addresses to routers in other areas?Answer: There are two situations to consider: (For simplicity, we use a simple topology : ABR uses link0 and link1 to connect to area 0 and 1 respectively.)1) ABR creates Summary LSAs (link0, 1) and (link1, 0), and floods them in area 1, 0 respectively.2) When a new subnet 10.1.1.0 is online in area 0, the attached router floods its Router LSA with this new address. When ABR receives this address, it creates Summary LSA (10.1.1.0, 1) and floods it.This article is the FAQ part of an OSPF simulation: ABR. To see how an ABR announce network addresses across areas, go to the external link listed below.External links for network simulation: 1. OSPF Simulation: Area Border Router (This article): /view.php?cid=931&protocol=OSPF&title=1.6%20Area%20Border%20Router 2. More network protocol simulation: /

access point vs router