How configure multiple areas in OSPF?

Step-by-Step Procedure

  1. Configure the device interfaces.
  2. Configure the router identifier.
  3. On each ABR, configure the primary interface for the OSPF area.
  4. On each ABR, configure the secondary interface for the OSPF area.
  5. If you are done configuring the devices, commit the configuration.

What is multiple area OSPF?

When a large OSPF area is divided into smaller areas, this is called multiarea OSPF. Multiarea OSPF is useful in larger network deployments to reduce processing and memory overhead. Multiarea OSPF requires a hierarchical network design.

Why use multi area in OSPF?

The reason you would create multiple area types is to avoid overwhelming routers with a huge routing table and topology database when they do not need to understand this information. To reduce router overhead in a large OSPF network, you can create different types of areas.

What is the OSPF multicast address?

OSPF uses multicast functions when interfaces are attached to broadcast networks, such as Ethernet. For all OSPF routers, these interfaces are joined to multicast address 224.0. 0.5.

What are LSA types?

LSA Types – Quick Overview

  • LSA Type 1: OSPF Router LSA.
  • LSA Type 2: OSPF Network LSA.
  • LSA Type 3: OSPF Summary LSA.
  • LSA Type 4: OSPF ASBR Summary LSA.
  • LSA Type 5: OSPF ASBR External LSA.
  • LSA Type 6: OSPF Group Membership LSA.
  • LSA Type 7: OSPF Not So Stubby Area (NSSA) External LSA.

Why OSPF has 2 multicast address?

OSPF uses two IP multicast addresses on broadcast and point-to-point networks: 225.0. 0.5 for all OSPF routers and 224.0. 0.6 for all DR/BDR (designated router/backup designated router) routers. Using IP multicast addresses is more efficient than using broadcast addresses.

Does OSPF use multicast or broadcast?

Can ABR be Asbr in OSPF?

An ABR by definition has links in two or more areas. In OSPF, routers always form the boundaries between areas. A router with links outside the OSPF routing domain is called an autonomous system boundary router (ASBR).

What is DR and BDR in OSPF?

In an OSPF broadcast network, OSPF elects one router to serve as the designated router (DR) and another router on the segment to act as the backup designated router (BDR). This minimizes the amount of repetitive information that is forwarded on the network. OSPF forwards all messages to the designated router.

Why is type 4 LSA required?

LSA 4 is generated by the ABR. Link ID in that is the router ID of ASBR and Adv. Router is the ASBR itself. LSA 4 is required to tell the routers in other areas how to reach the ASBR to get to external network eventually.