Open Shortest Path First (OSPF) Summary

Hi All,

Here is the list of summary for OSPF. I will add every topic details in upcoming blogs.

What is OSPF ?

– OSPF is Open Standard Interior Gateway Protocol (IGP)

– Link State Routing Protocol

– Uses Dijkstra SPF Algorithm

– Supports VLSM And Summarisation

– works on IP port 89.

OSPF Features:

– Standard Based

– Fast Convergence

– Hierarchy through areas

– Large Scalability

– Use Dijkstra SPF Algorithm for calculation

– Guarantees Loop-Free Topology

– Bandwidth based metric

– Uses reliable multicast and unicast updates

– Topology Summarisation

– All Routers agree on overall topology

– Actively Tracks neighbours adjacencies

– Event Driven incremental Updates

– Control Plane Security

– Authentication – Clear Text, MD5, SHA, IPSec, etc.

– Two Version –

OSPF v2 – For IPv4 Stack only

OSPF v3 – For IPV4 and IPv6 Stack

OSPF Hello Packet fields

– Local Router ID

– Local Area ID

– Local Interface subnet mask

– Local interface priority

– Hello Interval

– Dead Interval

– Authentication type and password

– DR/BDR address

– Options

– Router IDs of other neighbours on the link.

OSPF Adjacency States:

Down

Init

Attempt

2-Way

Exstart

Exchange

Loading

Full

Area Types:

– Backbone Area

– Standard Area

– Stub Area

– Totally Stub Area

– Not-So-Stub Area

LSA Types:

– Type 1 – Router LSA

– Type 2 – Network LSA

– Type 3 – Network Summary LSA

– Type 4 – ASBR summary LSA

– Type 5 – External LSA

– Type 6 – Group Membership LSA (Multicast Extension to OSPF) – not currently used.

– Type 7 – NSSA External LSA

– Type 8 – Link-local only LSA for OSPF v3.

– Type 9 – Link-local opaque LSA

– Type 10 – Area-local opaque LSA

– Type 11 – AS opaque LSA

OSPF Network Types:

– Brodcast

– Non-Broadcast

– Point-to-point

– Point-to-Multipoint

– Point-to-Multipoint Broadcast

– Loopback

 OSPF Packet Types:

– Hello

– DBD (Database Description)

– LSR – Link State Request

– LSU – Link State Update

– LSAck – LSA Acknowledgement

How OSPF Works?

 – Neighbour Discovery

– Exchange or share Topology Table

– Best Path Selection

– Neighbour and Topology Maintenance

 

#DV

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s