10 lecture - ospf part1 , introduction to ospf , areas and abr
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OSPF is an IGP routing protocol that uses link-state advertisements to share routing information between neighbors quickly. Routers establish adjacencies by exchanging Hello packets to elect a Designated Router and Backup Designated Router. Areas connect routers and allow different topology tables; area 0 connects all other areas. OSPF uses the SPF algorithm for each router to calculate the shortest path tree based on interface costs and shares this information through LSAs within an area.
10 lecture - ospf part1 , introduction to ospf , areas and abr
- 1. Lecture 10 - OSPF Part1 , Introduction to OSPF , Areas and ABR 1
- 2. What is OSPF • IGP • RFC 2328 by IETF • Link-state advertisement (LSA) 30 Minutes & immediately • Exam test on single Area 2
- 3. Areas • All areas connect to area0 • Same topology table within area 3
- 4. OSPF Neighbor Adjacencies • Hello protocol……….. Bidirectional communication Router ID 32-bit number (higher IP address on an active interface) Hello and Dead intervals*(4 x 10 Sec) Neighbors Area ID+ Router Priority (8 bit number to elect DR and BDR) DR IP Address BDR IP Address Authentication Password Stub Area Flag 4
- 5. SPF Algorithm Each router at the root of a tree auto-cost reference-bandwidth ref-bw Cost = reference bandwidth / interface bandwidth (in bps) 5