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Free Cisco Lab Packet Tracer Activity OSPF Multiarea

Posted by: admin  :  Category: CCNA, OSPF, Packet Tracer




This lab has been designed as a Cisco Packet Tracer activity but I have provided the topology for GNS as well.

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In this lab scenario you will configure OSPF routing protocol across multiple OSPF areas using Ethernet and Serial links connecting 6 routers and 5 switches. You will also configure a Server and 4 PC workstations and verify their connectivity. The following is a brief description of the area you will be configuring.  

OSPF Multi Area Types:

An OSPF domain is divided into areas that are labeled with 32-bit area identifiers. The area identifiers are commonly written in the dot-decimal 0.0.0.1 or decimal format (e.g., area 1).

Areas are logical groupings of hosts and networks, including their routers having interfaces connected to any of the included networks. Each area maintains a separate link state database whose information may be summarized towards the rest of the network by the connecting router. Thus, the topology of an area is unknown outside of the area. This reduces the amount of routing traffic between parts of an autonomous system. (An ABR simulation shows how an ABR lets areas know each others’ network addresses by flooding Summary LSA.)

Backbone Area:

The backbone area (also known as area 0 or area 0.0.0.0) forms the core of an OSPF network. All other areas are connected to it, and inter-area routing happens via routers connected to the backbone area and to their own associated areas.

The backbone area is responsible for distributing routing information between non backbone areas. The backbone must be contiguous, but it does not need to be physically contiguous; backbone connectivity can be established and maintained through the configuration of virtual links.

Stub Area:

A stub area is an area which does not receive route advertisements external to the autonomous system (AS) and routing from within the area is based entirely on a default route. A Stub Area simulation shows how an ABR deletes type 4, 5 LSAs from internal routers, sends them a default route of 0.0.0.0 and turns itself into a default gateway. This reduces LSDB and routing table size for internal routers.

Totally Stubby Area:

A totally stubby area is similar to a stub area. However, this area does not allow summary routes in addition to not having external routes, that is, inter-area (IA) routes are not summarized into totally stubby areas. The only way for traffic to get routed outside of the area is a default route which is the only Type-3 LSA advertised into the area. When there is only one route out of the area, fewer routing decisions have to be made by the route processor, which lowers system resource utilization.

Not-So-Stubby Area:

A not-so-stubby area (NSSA) is a type of stub area that can import autonomous system external routes and send them to other areas, but still cannot receive AS-external routes from other areas. NSSA is an extension of the stub area feature that allows the injection of external routes in a limited fashion into the stub area. A case study simulates an NSSA getting around the Stub Area problem of not being able to import external addresses. It visualizes the following activities: the ASBR imports external addresses with a type 7 LSA, the ABR converts a type 7 LSA to type 5 and floods it to other areas, the ABR acts as an “ASBR” for other areas.

Virtual Link Area:

All areas in an Open Shortest Path First (OSPF) autonomous system must be physically connected to the backbone area (Area 0). In some cases, where this is not possible, you can use a virtual link to connect to the backbone through a non-backbone area. You can also use virtual links to connect two parts of a partitioned backbone through a non-backbone area. The area through which you configure the virtual link, known as a transit area, must have full routing information. The transit area cannot be a stub area.

 

  Free Cisco Lab Packet Tracer Activity OSPF Multi Area (3,899 hits)

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One Response to “Free Cisco Lab Packet Tracer Activity OSPF Multiarea”

  1. raipraveen83 Says:

    awesome lab topology with solution it really help me to understand OSPF.waiting for few more stuffs

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