OSPF Neighbor States

OSPF, or Open Shortest Path First, is a popular routing protocol used in many networks today.

One of the benefits of using OSPF is its ability to dynamically determine the best path to send traffic.

In this post, we'll take a look at the different OSPF neighbor states that can be seen in a network and what they mean.

What is OSPF and Why do you need it?

OSPF is a routing protocol commonly used in network settings. It allows multiple devices within a network to communicate and exchange data by finding the most efficient paths for transmission. This helps to prevent network congestion and maintain optimal performance. OSPF also allows for scalability, allowing it to adjust easily as networks expand or change.

In addition, it offers high levels of security through authentication measures. While there are other routing protocols available, OSPF has proven to be a reliable and efficient option for many organizations. When implementing a new network infrastructure, considering the needs and capabilities of various routing protocols can help ensure smooth and successful operation.

What does "OSPF Neighbor States" mean?

In order for OSPF to function properly, neighboring routers must exchange information and establish a neighbor state with one another. These OSPF neighbor states are crucial for establishing successful communication between routers and determining the best pathways for data transmission.

The eight possible OSPF neighbor states are Down, Attempt, Init, 2-Way, Exstart, Exchange, Loading, and Full. Let's talk about these OSPF neighbor states in detail.

1. Down:

The first of many OSPF neighbor states is "down." When a device is in the "down" state, it means that there is currently no hello package being received from that device. This could be due to a physical issue, such as a broken network cable, or a software issue, such as incorrect configuration parameters. In any case, it is important to troubleshoot and resolve this issue as quickly as possible, as it can greatly impact the network’s overall performance.

2. Attempt:

In a network, the "attempt" OSPF state is only applicable in a non-broadcast multi-access (NBMA) environment. In this type of network, routers use unicast hello packages to establish adjacencies with their neighbors. The "attempt" neighbor state indicates that a router has received a hello package and is attempting to become neighbors with the sending router.

3. Init:

In OSPF networking, "init" refers to a neighbor state in which a hello package has been received, but no router ID has been received. This generally indicates that the exchange of information between routers has just begun, and the network is still in the process of establishing connections.

4. 2-Way:

"2-way" as an OSPF state refers to bi-directional communication between routers. In order for two routers to become neighbors, they must first establish bi-directional communication and exchange Hellos. Once bi-directional communication has been established, the neighbor state will show as "2-way." From there, the routers exchange link state information and form adjacencies, ultimately creating a fully functional OSPF network. Additionally, BDs and BDRs are elected at the end of this stage.

5. Exstart:

The "Exstart" state in OSPF neighbor relationships means that both parties have agreed to exchange link state information, and a master-slave relationship has been established. In this state, the exchange of link state information begins and continues until both parties declare that they have nothing further to exchange. It is important for OSPF routers to exchange this information so they can accurately calculate the best paths for data transmission between networks.

6. Exchange:

In the OSPF routing protocol, the exchange neighbor state is when two routers exchange Database Description (DBD) packets. This exchange contains information about the router's links and their associated metrics. Once this exchange is complete, the routers move on to the loading state, where they exchange Link State Advertisements (LSAs) and build their topology maps. The exchange state is an important step in establishing a neighbor relationship and ensuring that both routers have the same information. It is vital for proper communication and routing within a network.

7. Loading:

"Loading" indicates that the actual link state exchange is taking place. This means that the router is sending and receiving Link State Advertisements (LSAs) through designated neighbors, with the aim of building a comprehensive Link State Database. Once this process is completed, the neighbor state will change to "Full," indicating that all link state information has been exchanged successfully.

8. Full:

"Full," as one of the OSPF neighbor states, refers to routers that are fully adjacent to each other and have fully synchronized their link-state databases. This is the normal and desired state for routers in an OSPF network, as it ensures efficient communication and routing. In contrast, a router in the "Init" or "Down" neighbor state may indicate a problem with connectivity or configuration. So while seeing routers in a "Full" state may not be exciting news, it is essential for smooth network operation.

To Sum Up:

OSPF Neighbor States is an important chapter in understanding the working of OSPF.

The article provides a comprehensive summary of the states that a neighbor can be in and how routers behave under different conditions.

We hope you found this information useful.

If you are interested in learning more about networking or need to refresh your skills, we offer excellent CCIE Enterprise Infrastructure course on our IT courses list.

Created by
Stanley Avery

I am a certified network engineer with over 10 years of experience in the field. I have a deep understanding of networking and IT security, and I am always looking for new challenges.

View profile

Daniel Lardeux
Daniel Lardeux Senior Network Consultant at Post Telecom

I passed the CCDE Practical exam and Orhan’s CCDE course was very important contributor to my success. I attended the CCDE course of Orhan Ergun in July and it was exactly what I needed, Orhan is taking the pain to break down the different technologies.

Roy Lexmond
Roy Lexmond Senior Network Designer at Routz CCDE #20150017 & CCIE R&S; #26557

After I attended Orhan Ergun’s CCDE course I passed the CCDE practical exam.I really enjoyed the course a lot ...

Nicholas Russo
Nicholas Russo Network Consulting Engineer (CCDE/CCIEx2), Cisc

I signed up for Orhan’s CCDE training. This training is very technically detailed and the use-cases, quizzes, scenarios, and mind maps are all great resources in the overall training program. Orhan teaches his students to think like a network designer ...

Slide Heading
Slide Heading Network Systems Engineer at Conscia A/S CCIE #42544 (SP) & CCDE #20160015

Orhan is forcing you to take off the implementation hat that most of us have been wearing for many years, instead he is providing a new fancy design hat, which makes you see and deal with the issues presented ...

Kim Pedersen
Kim Pedersen CCIE in RS and SP (#29189) CCDE#20170021

I’ve used Orhan’s self-paced CCDE training material. If you are interested in knowing how all the technologies go together in a coherent design i can highly recommend it.I also enjoyed the Quizzes which helped pick out my weak spots in selecting ...

Laurent Metzger
Laurent Metzger 3xCCIE/CCDE Senior Network Architect

Hi Orhan. I passed the CCDE exam on February 22. I read everything that you put on your Self Paced CCDE Training course and it was very helpful in my success. Thank you very much.

Martin J. Duggan
Martin J. Duggan Network Architect at AT&T;, Ciscopress Author CCDE #20160006 & CCIE#7942

I attended Orhan’s April 201610 days CCDE Bootcamp. I am CCDE now !

You can tell Orhan has a great deal of experience, it really comes through when he presents his design case studies and the CCDE Practical scenarios.

Muhammad Abubakar
Muhammad Abubakar Lead Network Architect – CCDE #20160016 2xCCIE #26693 2xJNCIE VCIX

Your excellent CCDE materials and amazing Bootcamp helped me tremendously through my learning journey.Also thank you very much for being available whenever I have a design question or a complex design topics. I can’t compare your design skills ...

Jennifer Pai
Jennifer Pai Network/Security Engineer at KNET Technology

Thanks Orhan very much for this course. It helped strengthen my “Network design mind”.

Ruslan Silyayev
Ruslan Silyayev Solution Architect at R.I.S.K Company

Training by Orhan is not a CCDE preperation training only. It will be useful for engineers which are dealing with design. You want to pass CCDE exam or learn network design, then don’t look at anywhere else!

Sameer Meher
Sameer Meher Solutions Architect at 23 Wards/Japan

Orhan Ergun’s CCDE course was really very good. CCDE Level Intelligence was delivered very well and with very useful case studies and the scenarios, I am thankful to Orhan for all his help!

Ken Young
Ken Young Senior Technical Architect Province of Nova Scotia, 2xCCIE #41597 | CCDE #20170047

If anyone wants to understand network design and architecture, also pass CCDE exam , I recommend you to attend Orhan’s online courses! I am a CCDE now but learning is a journey, we will be together in your other courses too Orhan!

Matt Cross
Matt Cross Technical Architect at Heartland – CCDE #2019::7

Orhan did an excellent job of filling in the gaps of knowledge that I had that took me to the finish line of the practical exam CCDE. The community of people that Orhan facilitates are both engaging and supportive of the journey to CCDE. Orhan ...

Shiling Ding
Shiling Ding Sentinel Technologies – CCDE #2019::12

Just passed the CCDE Practical exam! I attended Orhan Ergun’s CCDE training program , used Orhan’s Instructor Led and Self-Paced CCDE training and Online CCDE Practical Scenarios during my CCDE journey. Orhan’s CCDE In Depth book is an excellent summary ...

Abelardo Basurto
Abelardo Basurto Solutions Architect at Cisco Systems – CCDE 2018::6

Hi everyone, I’ve just passed the CCDE Exam. My Number is CCDE 2018::6 I attended to Online CCDE Bootcamp of Orhan. I want to thank Orhan not only for the great book and bootcamp, but also for his commitment, availability and willingness to assist the ...

Hady Mohamed Abdellah
Hady Mohamed Abdellah Network Architect Hamad International Airport Qatar – CCDE 2018::1

Hi guys, I’m so happy that I passed the exam. I’ve already got my number CCDE 2018::1. Thanks to Orhan for being the best CCDE instructor in the world. I highly recomend Orhan’s CCDE Training and In-Depth-CCDE ...

Bryan Bartik
Bryan Bartik Sr. Systems Engineer at CompuNet – CCDE 20170059

Hi Orhan I passed CCDE Practical exam on November 2017 ! I really enjoyed your materials and quizzes and use cases. They were definitely helpful in my preparation. Thanks a lot !

Giedrius Trapkauskas
Giedrius Trapkauskas Network Solutions Architect at Liberty Global – CCDE 20180004

I attended Orhan’s CCDE Training in Istanbul and it was very helpful in my preparation. I passed the exam recently and I want to say Thank you Orhan! For those who want to pass the CCDE exam, definitely start with ...

Alaa Issa
Alaa Issa Sr.Solutions Architect – CCDE#20180033 3xCCIE ( Collab|DC|Security )#27146

I registered to Orhan’s training in Feb 2017. From that time, I attended Orhan’s training several times. The depth of knowledge which Orhan has is amazing, and how to present such consistent knowledge to the ...

Mazin Ahsan Design Lead Engineer | Solutions Engineer | CCDE License # 20160030 | CCIE Licence # 23892

I passed the CCDE Practical Lab exam on November 17,2016 from supplications of elders and dedication from my Sensei Mr. Orhan Ergun I took different CCDE bootcamps in the past. Orhan has the most depth and expertise ...

Jeff Patterson CCDE# 2018::11

Hi Orhan I wanted to pass along my appreciation for the outstanding training material. I used the online CCDE training provided by Orhan as well as the In-Depth-CCDE book and passed the exam in February 2018. Thank you Orhan!

Mehdi Sfar
Mehdi Sfar Network and Security Architect / CCDE #20210003 | CCIE R&S; #51583

I signed up for Orhan’s CCDE Self paced Course. This course, along with the CCDE In Depth book, helped me for my CCDE Practical as well as Written exams. It pushed me to ask the "WHY" questions and allowed ...

Related courses