• Skip to main content
  • Skip to header right navigation
  • Skip to site footer

Roger Perkin

Network Automation Architect

  • Network Automation
    • Network Automation Courses
    • What is NetDevOps?
    • Workflow Orchestration
    • Ansible Automation Platform
    • Ansible Workshop
    • What is Network Automation?
    • Network Automation Tools
    • ContainerLab
    • Ansible Training
      • What is Ansible?
      • Ansible Tutorial for Beginners
      • Ansible Network Automation
      • Ansible Inventory Example
    • Python Network Automation
      • Nornir
      • Python Network Automation Course
      • Python for Network Engineers
      • Python VENV / Virtual Environment Tutorial
      • Python Tutorial for Beginners
      • pyATS
    • Network Source of Truth
      • NetBox
      • Infrahub
    • NetDevops
    • DevOps Tutorial
      • Git Training
      • Terraform Training
      • Linux Training
      • Kubernetes Training
      • Devops Training Course
      • Azure Devops Training
    • Terraform
    • GIT
      • Git Commands
      • What is GitHub?
    • Docker Training
    • Confluence
    • Microsoft Azure
  • Cisco
    • ISE
    • SD WAN Training
    • Password Recovery
    • Software-Upgrade-Guides
    • BGP
    • Data Center
    • WIRELESS
  • CCIE
  • Blog
  • About
    • My Red Special Guitar
  • Contact

OSPF LSA Types Cisco for IPv4 Explained

Home » OSPF Tutorials

This post will explain the Cisco OSPF LSA Types hopefully in an easy to understand format. These are my study notes for the CCIE R&S Lab exam.

The main LSA types are:

 LSA type 1 (Router)

Every router generates a type 1 LSA with the state of each of their links, there are 3 types of links

  • Stub -none or one neighbor
  • Transit – more than one neighbor
  • Point to Point – links with other routers

Basically an LSA type 1 describes all the links that a router has, including loopbacks.

The link state ID is the Router ID

LSA type 2 (Network)

Type 2 LSA’s are present on a multi-access link – a DR exclusively generates type 2 LSAs and the tell the other routers about the network and the routers connected to them

Both LSA types 1 and 2 exist in all areas and are never flooded outside of the area. Other LSAs are advertised within an area depending on the area type, these are all described below.

The link state ID is the interface IP of the DR

LSA type 3 (Summary)

Generated by the ABR to describe a route to neighbors outside the area. (Inter-area routes)

For type-3 LSAs, the Link-State ID is the IP address of the subnet that is being advertised.

LSA type 4 (ASBR Summary)

The link state ID is the Router ID of the ASBR that is being advertised.

External routes – LSA type 5

The link state ID is the IP address of the subnet that is being advertised.

NSSA external routes – LSA type 7

To summarise:

LSA Type 1 – Router – contains router links and state and is flooded into the area of origin

LSA Type 2 – Network – generated by DR – lists all attached routers – flooded into the area of origin.

LSA Type 3 – Network Summary – generated by ABR’s sent into an area to advertise prefixes to other areas – flooded throughout the Autonomous System.

LSA Type 4 – ASBR Summary – generated by ABR’s – advertises the ASBR – flooded throughout the Autonomous System

LSA Type 5 – AS External – generated by ASBR – advertises external destination – flooded throughout the Autonomous System

LSA Type 7 – NSSA External – generated by the ASBR in a not so stubby area – advertises external destination.

Other related OSPF posts

  • Should you run OSPF over DMVPN?
  • OSPF Cost Calculation
  • Troubleshooting OSPF Hello Mismatch
Category: OSPF TutorialsTag: ospf area types, ospf lsa types
ansible course for network engineers
Get Access to my Ansible Course NOW
Previous Post:CCIE Lab Locations – CCIE Lab Exam Centers
Next Post:CCNA – Cisco Certified Network Associate

Sidebar

Hi I'm Roger Perkin,
Based in the UK working as a Network Automation Architect, CCIE #50038
About Roger | Twitter | Linkedin

python course for network engineers

Topics

Network Automation
Ansible
Python for Network Automation
CCIE
Cisco ISE
F5 Certification
BGP
OSPF
Network Automation Conferences
auvik promo banner
Pluralsight Trial

Git for Network Engineers

Ansible vs Nornir

Start learning today with my Network Automation Courses

Master Ansible, Python, Git, Nornir, Jenkins and more..


Buy me a coffeeBuy me a coffee

ansible network automation course

Have you seen my YouTube Channel?

YouTube Subscribe

Let’s get started

Take a look at my premium courses on Ansible, Nornir & Git or buy them all with the Network Automation Bundle!

Network Automation Courses

Navigation

Python VENV Tutorial
Python for Network Engineers

Network Automation
Network Automation Courses
Network Discovery Tools
Network Automation Conferences
Ansible Training
What is Ansible?
Devops Tutorial
Network Source of Truth
DevOps Glossary
Network Monitoring Software

Contact

Contact

Get in touch with me here

[email protected]

  • Twitter
  • LinkedIn
  • YouTube
Buy me a coffeeBuy me a coffee

Copyright © 2025 · Roger Perkin · All Rights Reserved · Privacy Policy – Terms