Is Area 0 required in OSPF?

An OSPF routing domain (AS) can consist of a single area, but in that case the single area must be Area 0. Only the backbone area can generate the summary routing topology information that is used by the other areas. This is why all interarea traffic must pass through the backbone area.

What is Area 0 called in OSPF?

According to the OSPF design principle, area 0 plays the role of the central node in the OSPF network. The link information of other areas is transmitted through area 0. This also means that all other areas must be connected to area 0. This area supports 1, 2, 3, 4, and 5 LSAs.

How many routers can OSPF Area 0 have?

Current ISP experience and Cisco testing suggest that it is unwise to have more than about 300 routers in OSPF backbone area 0, depending on all the other complexity factors that have been discussed. As mentioned in the preceding note, 50 or fewer routers is the most optimal design.

Can two area communicate without Area 0 OSPF?

There is only one way to use OSPF without an Area 0, and that is to use OSPF with a single area. If you only have one OSPF area, you can number it any way you like, but if you have even two areas, you must have an Area 0. Show activity on this post. OSPF can work efficiently without area 0 when there is only one area.

Why is OSPF Area O required?

Albeit OSPF is a link state protocol, the way OSPF handles inter-area traffic leaves it prone to routing loops. This is why OSPF must connect back to area 0 – to avoid routing loops.

What is a OSPF normal area?

Normal area This area connects to the AS backbone area through one or more ABRs (physically or through a virtual link) and supports type-3 summary LSAs and type-5 external link LSAs to and from the backbone area. ASBRs are allowed in normal areas.

What is OSPF area range?

OSPF area identifier in decimal format. Range: 0 to 4294967295.

Why is OSPF divided into areas?

In OSPF, a single autonomous system (AS) can be divided into smaller groups called areas. This reduces the number of link-state advertisements (LSAs) and other OSPF overhead traffic sent on the network, and it reduces the size of the topology database that each router must maintain.

What is a virtual link in OSPF?

Virtual links are used to extend Area 0 across another area. They also can be thought of as tunnels for LSAs. They are deployed in cases when areas become partitioned or an area does not border Area 0.

What is the importance of Area 0?

Area 0 is the trunk of your network whilst other areas are in essence branches. As we know every router in an area shares information about itself and the links it contains. This information is shared with all routers in an area. In turn, each router creates a link-state database.