OSPFOSPF

Open Shortest Path FirstOpen Shortest Path First

Table of Table of ContentContent

IP RoutesIP Routes OSPF HistoryOSPF History OSPF DesignOSPF Design OSPF Link StateOSPF Link State OSPF Routing TableOSPF Routing Table OSPF Data PacketsOSPF Data Packets

IP RoutesIP Routes

• ip route 15.235.16.0 255.255.255.0 10.120.0.2ip route 15.235.16.0 255.255.255.0 10.120.0.2• ip route 15.235.32.0 255.255.255.0 10.120.0.3ip route 15.235.32.0 255.255.255.0 10.120.0.3

15.235.20.0 /23

10.120.0.1

15.235.16.0 /24

10.120.0.2

15.235.32.0 /24

10.120.0.3

IP RoutesIP Routes

OSPF HistoryOSPF History

1970 1970 research on the SPF research on the SPF algorithm algorithm (invented by (invented by Dijkstra)Dijkstra)

1980s 1980s problems with RIP and large problems with RIP and large networksnetworks

1988 1988 Internet Engineering Task Internet Engineering Task Force (IETF)Force (IETF)

OSPF DesignOSPF Design

Division into star of areasDivision into star of areas All areas are connected to backboneAll areas are connected to backbone

area 0 area 0 Traffic between areas have to pass Traffic between areas have to pass

area 0area 0Critical if the network of area 0 failsCritical if the network of area 0 failsHigh bandwith requiredHigh bandwith required

OSPF DesignOSPF Design

Table of Table of ContentContent

IP RoutesIP Routes OSPF HistoryOSPF History OSPF DesignOSPF Design OSPF Link StateOSPF Link State OSPF Routing TableOSPF Routing Table OSPF Data PacketsOSPF Data Packets

OSPF Link StateOSPF Link State

Uses „Hello“ Messages to identify Uses „Hello“ Messages to identify neighboursneighbours

Neighborhood is formedNeighborhood is formed& Routing Tables are build& Routing Tables are build

Dijkstra's SPF algorithmDijkstra's SPF algorithm

OSPF Routing TableOSPF Routing Table

Number of hops : 65535Number of hops : 65535 Tree Tree

• Router is the rootRouter is the root MetricsMetrics Multipath RoutingMultipath Routing

OSPF Data PacketsOSPF Data Packets

Type:

HelloDatabase description Link-state requestLink-state updateLink-state acknowledgment

Thanks for your attention!Thanks for your attention!

QuestionsQuestions

Of what type can OSPF Data Packets Of what type can OSPF Data Packets be?be?

What is critical about area 0?What is critical about area 0?