OSPF Wildcard Masks | Cisco CCNA 200-301

[@universalponcho]

Currently doing networking. You have saved me! I had to edit this comment. Yeah this video is a bit long however well worth the watch. You sir are a genius! Which ever two humans disliked this film really need to reevaluate their lives.. Thank you very much for your time and effort. 🙌🤙

[@KeithBarker]

Great to hear!

[@eternalblue4660]

Very informative. Sometimes I prefer longer styled videos like yours because you go into the fundamentals and really make sure the person is understanding what is going on, especially with OSPF as it can be tricky at first but not impossible to learn.

[@KeithBarker]

Thank you EternalBlue!

[@memontaser]

It looks like u made the OSPF so easy and clear for me and for all... Thanks Keith :)

[@KeithBarker]

Great to hear!

[@jemuelbjeroham1228]

Keith, you are always phenomenal... Thanks for your videos. 😊

[@KeithBarker]

My pleasure!

[@winfredmathias1222]

Thank you so much sir for this...Well explained. Love you for this

[@KeithBarker]

You are most welcome

[@syedshohidahmed9880]

Thank you for the videos, it's been a fantastic refresher for me!

[@KeithBarker]

Great to hear, thank you Shohid!

[@corradocaocci413]

Great Lesson! Thank you

[@KeithBarker]

Glad you liked it!

[@Denkserwtinabalw]

Best teacher ever

[@KeithBarker]

Thank you Kwstas.

[@majiddehbi9186]

thx for ur time

[@KeithBarker]

Happy to do it, thanks for the feedback majid dehbi.

[@reeteshtimilsina5249]

Thankyou so much... love this ..

[@KeithBarker]

Thank you Reetesh!

[@derrik-bosse]

It seems like a lot of commands for OSPF routing aren't supported by Packet Tracer

[@majiddehbi9186]

heay keith just to tell u is it true that packet tracer doen't support the command " show ip ospf int brief"

[@KeithBarker]

Thank you majid dehbi

[@Peter-kj9pq]

I am confused the last subnet you added on loop back 5. You did a wildcard mask of 0.0.0.0 I am interpreted that as very specific. Except when you did the brief it put the network in as a /16 instead of /32. Although your wildcard mask says otherwise. This behavior is confusing. Can you elaborate if possible thanks.

[@KeithBarker]

Thank you Peter. I appreciate the question. It is at around the 53 minute mark when I added the loop 5 and a network statement for it in OSPF. kzbin.info/www/bejne/i6W4aZebpKp7bs0 To identify the networks/interfaces that should be put into OSPF, it is logically 3 steps. 1. Identify which interfaces match the network statement. 2. Enable OSPF on those interfaces. 3. Include any of those interfaces' directly connected networks in OSPF (in the area specified by the network statment). Here is an example: Int gig 0/0 10.1.2.1 255.255.255.240 (connected to network 10.1.2.0/28) Int gig 0/1 10.1.2.17 255.255.255.240 (connected to network 10.1.2.16/28) Int gig 0/2 10.1.2.33 255.255.255.240 (connected to network 10.1.2.32/28) router ospf 1 network 10.0.0.0 0.255.255.255 area 0 (Any interfaces starting with 10.x.x.x will match) Result, those 3 interfaces are included in OSPF AND, drum roll please.... The IP networks associated with those interfaces are included as OSPF routes. This means that these 3 networks, 10.1.2.0/28 10.1.2.16/28 10.1.2.32/28 Would all be in OSPF. IF, IF, IF.... instead we used the network statement of 10.1.2.17 0.0.0.0 area 0 Then, the only interface in OSPF would be Gig 0/1 and the only network included would be 10.1.2.16/28 Let me know if that helps, and thanks for watching and for your question. -Keith

[@Peter-kj9pq]

Keith thanks for the clarification and reply. I see at the 53.22 mark is where it’s being classed as a /16 network. Only listening on the one interface ip address further on in the video. Thank you for all you do for the community. Will keep learning. 👍

[@MustafaAliraqii]

@@KeithBarker Great reply! This was a point of confusion to me. So the network command is actually taking a network ID where a router's interface residing in and then specify through a wild-card what portion of that Network ID need to match in other network IDs in order for OSPF to operate on them. My question is: Why we take Network ID as a reference with wildCard as long as the wildCard eventually takes only the numbers(bits) it needs. Why not taking any other random IP? For example, why not take this random IP 10.1.2.3.4 not the net ID: Network 10.1.2.3.4 0.255.255.255 area 0 As long as the result would be any network starting with number 10.

[@KeithBarker]

@@MustafaAliraqii If we used the network statement of network 10.1.2.3 0.255.255.255 area 0 The output of show ip protocols would show a network statement of 10.0.0.0 0.255.255.255 area 0 In short, it will 0 out any octets in the IP address portion that the wildcard mask said didn't matter for matching. Hope that helps.

[@MrTahoeman8]

If you are configuring OSPF using loops backs. What is the IP address for the physical interfaces?

[@KeithBarker]

Thank you MrTahoeman8. Feel free to join my Discord sever. Lots of people there helping each other out. Each Saturday at 10am Pacific I hold my "Office Hour" where learners can ask questions about the topics they are studying. Mostly focusing on Cisco CCNA 200-301 topics. Feel free to join us there live if you are available. Here is the link ogit.online/Join_OGIT_on_Discord Thanks again MrTahoeman8!

[@tanveersardar5574]

Dear Keith, I have configured ipsec tunnels (point to multi points) one end I have Cisco 3650 catalyst switches with HSRP (using VIP as source address of tunnels) while remote sites have separate devices with physical address on their interfaces. Now I am facing an issue that one site will remain up while other site goes down. I didn't add reverse route command while configuring tunnel at main site (cisco 3650 switch). I am able to swap both tunnels but unable use both simultaneously. Please suggest your input in this regard. Best Regards Tanveer

[@KeithBarker]

Hi Tanveer! Sounds like an interesting problem. I don't have the bandwidth available here to dive into troubleshooting that with you, but hope you find a solution.

[@tanveersardar5574]

Dear@@KeithBarker I will b thankful if you have time to demonstrate in gns3 lab at your own and also upload on channels as well. Regards

[@shezzy97]

Thank you Keith for this refresher on OSPF, can you not use the subnet mask in the network statement or you have to use the wild card mask? I recall using the subnet mask in OSPf configuration might have been on an ASA.

[@KeithBarker]

Thank you for the question! The ASA uses normal masks for its network statement. The routers use the wildcard statement. Good memory.

[@ardentdfender4116]

On 3/4 of your CCNA OSPF video. Loopbacks and it's "true purpose" continue to seem sketchy and fuzzy to me here and in the course. From the video, I seem to understand that a Router can have multiple or many Loopback & IP Addresses. Yet, there wasn't any place where you really explained what the purpose it serves in the various loopback and its IP Addresses. It helped to watch the video for cementing OSPF Wildcards. However, I'm no clearer in understanding Loopbacks and their IP Addresses at all. As well as what determines the IP Address for a Loopback on the Router.

[@KeithBarker]

Thank you Ardent Dfender! ogit.online/block-size I spend some extra time on Loopback interfaces in the video above. I am going through all my comments, and may have already mentioned the video, but wanted to be sure you saw my note, so am including it here as well. I appreciate your interest and participation and feedback. Keep it up!!!!

[@mmd8075]

This guy is networking Rod Stewart :D

[@KeithBarker]

Thank you M Md!

[@notorioustcp4628]

Does anyone have a favorite study book for CCNA?

[@KeithBarker]

Thank you for the question. Right now, the official cert by Wendell Odom is one of the more popular, and reliable, resources in books.

[@tabishkhan9843]

Thanks for this video. Actually, i want to ask you a question. I would appreciate your response. assume that I have three networks directly connected to the router. These networks are 1) 192.168.1.0/24 2) 192.168.10.4/30 3) 192.168.10.12/30 My question is that can we use only and only one wildcard to match all the three networks. that wildcard is 0.0.0.3 How? 192.168.1.0= 1100 0000. 1010 1000. 0000 0010. 0000 0000 192.168.10.4= 1100 0000. 1010 1000. 0000 1010. 0000 0100 192.168.10.12= 1100 0000. 1010 1000. 0000 1010. 0000 1100 = 0000 0000. 0000 0000. 0000 0000. 0000 0011 That's how i figured out wildcard to be 0.0.0.3 for all these three networks.

[@KeithBarker]

Thank you for the question Tabish khan. The 3rd octet for net 1 is different for 2 and 3, so it would need additional wildcard bits to account for that.

[@Ms.Robot.]

You are doing a great job, but you keep using /24 wildcards. And I need to understand other wildcards and what numbers they apply to. Example: 10.16.80.63 0.0.0.7