Mod1-ICT

Open Shortest Path First - OSPF

A link-state routing protocol that uses the SPF algorithm; faster convergence and scalability than RIP

Router Interface Protocol - RIP

used to disseminate information about networks and interfaces to other routers.

Link-State Database - LSDB

Contains all link-state advertisements for an area; identical across all routers in the same area.

SPF Algorithm (Djikstra)

Calculates the shortest path tree and determines the best routes based on cumulative cost

OSPF Areas

Logical Divisions of an OSPF domain; Area 0 (backbone) is best practice.

Single-Area OSPF

All routers in one area (usually area 0)

Multiarea OSPF

Multiple areas with ABRs; reduces table size and limits LSA flooding

OSPFv2 vs OSPFv3

v3 supports IPv4, v3 support IPv6

Hello
Database Description
Link-State Request
Link-State Update
Link-State Acknowledgement

OSPF packets (5 types)

DR (Designated Router)

Collects/distributes LSA's on Multiaccess networks.

BDR (Backup Designated Router)

Takes over if DR fails

Drother

Routers that are neither DR no BDR.

Multicast 224.0.0.5

for all OSPF routers

Multicast Address 224.0.0.6

for all DRs and BDRs