OSPF operates within a single autonomous system (AS). Networks within this single AS, however, can be divided into a number of areas. By default, Area 0 is created. Area 0 can either function alone or act as the OSPF backbone for a larger number of areas. Each OSPF area is named using a 32-bit identifier which in most cases is written in the same dotted-decimal notation as an IP4 address. For example, Area 0 is usually written as 0.0.0.0.
The topology of an area is maintained in its own link state database and is hidden from other areas, which reduces the amount of traffic routing required by OSPF. The topology is then shared in a summarized form between areas by a connecting router.
OSPF Area Type
The backbone area (Area 0) is the core of an OSPF network. All other areas are connected to it and all traffic between areas must traverse it. All routing between areas is distributed through the backbone area. While all other OSPF areas must connect to the backbone area, this connection doesn’t need to be direct and can be made through a virtual link.
Normal OSPF Area
In a normal OSPF area there are no restrictions; the area can carry all types of routes.
Stub OSPF Area
A stub area does not receive routes from other autonomous systems. Routing from the stub area is performed through the default route to the backbone area.
The Not So Stubby Area (NSSA) is a type of stub area that can import external routes, with some limited exceptions.
OSPF Router Types
OSPF Router Types Within an OSPF area, routers are divided into the following categories. Internal Router —A router with that has OSPF neighbor relationships only ...
Configure OSPF OSPF determines routes dynamically by obtaining information from other routers and advertising routes to other routers by way of Link State Advertisements (LSAs). ...
OSPF Areas Tab
OSPF Areas Tab Network > Virtual Router > OSPF > Areas The following fields describe the OSPF area settings: OSPF – Areas Settings Description Areas ...
OSPFv3 Areas Tab
OSPFv3 Areas Tab Network > Virtual Router > OSPFv3 > Areas Use the following fields to configure OSPFv3 areas. OSPv3 – Areas Settings Description Authentication ...
Configure OSPFv3 OSPF supports both IPv4 and IPv6. You must use OSPFv3 if you are using IPv6. Configure general virtual router configuration settings. See Virtual ...
Advanced LSVPN Configuration with Dynamic Routing
Advanced LSVPN Configuration with Dynamic Routing In larger LSVPN deployments with multiple gateways and many satellites, investing a little more time in the initial configuration ...
OSPF Network > Virtual Router > OSPF Configuring the Open Shortest Path First (OSPF) protocol requires you to configure the following general settings (except BFD, ...
OSPF Neighbors Two OSPF-enabled routers connected by a common network and in the same OSPF area that form a relationship are OSPF neighbors. The connection ...
Site-to-Site VPN with Static and Dynamic Routing
Site-to-Site VPN with Static and Dynamic Routing In this example, one site uses static routes and the other site uses OSPF. When the routing protocol ...