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Ed, you're a bit of a savant. I will never understand how you can have such a grasp of all of this. Your instruction is fantastic, I will have to review this when I'm not half asleep, but what you share with us is AMAZING.
I want to say thank you, I am bluffed by how you have explained that, I have purchased many of CCNA & CCNP courses, but no one has explained it the way you did. Thank you
I have been searching for almost 7 years to know what is the LSA Types differences and their nonsense theory and you nailed it in a shot. Superb. It feels like no instructor knows what exactly LSA's are except you.
Sorry to be that person but there are actually 11 types of LSAs (OSPF). LSA Type 1 Router LSA LSA Type 2 Network LSA LSA Type 3 or 4 Summary LSA & ASBR LSA LSA Type 5 Autonomous System External LSA LSA Type 6 Multicast OSPF LSA Type LSA Type 7 Defined for Not-So-Stubby-Areas LSA Type 8 External Attribute LSA for BGP LSA Type 9,10,11 Opaque LSA RFC 5250 back in 2008 discusses these. Cisco, one, it not the largest, vendor which many people are familiar with, only supported 1-5 for the longest but other vendors supported OSPF LSAs (6-11) well before especially with the advent of Traffic Engineering (10-11 "Opaque" LSAs). Very good explanation on the 5 types you discussed here.
Thank you very much. I really appreciate your explanation with moving diagrams. I currently prepare myself for an exam and it was really hard for me to imagine how it works just out of the slides. Before this video I didn't even understand where the LSA are all send to.
Thank you for your great work, just one remark regarding type 4/5 LSA, you mentioned that router 6 (which is an ASBR) introduced itself to router 4 by type 1 LSA, assuming that this type 1 LSA will be forwarded by the ABR R2 as a type 3 LSA to other areas, so other areas will know about R6, so there will be no need for Type 4 LSA as a helper for this redistributed type 5 LSA !!
>> assuming that this type 1 LSA will be forwarded by the ABR R2 as a type 3 LSA This isn't entirely correct. The actual Type 1 LSA will not be forwarded. Instead, only specific information from _within_ the Type 1 LSA is forwarded -- specifically _only the IP Subnets contained in the Type 1 LSA are forwarded._ The Routers identity (which is included in Type 1 LSAs) is not included in the Type 3 LSAs. To really understand it, I'd recommend the LSA Deep DIve videos: Type 1 & 2: ua-cam.com/video/1FOBkIoDbCc/v-deo.html Type 3: ua-cam.com/video/8fFtU5W9WGk/v-deo.html
Thanks for both contributions. I'd like to make a remark about LSA type 5 that originates from an external non-OSPF domain in an NSSA area. Shouldn't it be converted from type 7 to type 5?
Noted about BGP, Randy. As for EIGRP, I wrote three EIGRP articles you might enjoy: EIGRP Explained : www.practicalnetworking.net/stand-alone/eigrp-terminology/ EIGRP Metric : www.practicalnetworking.net/stand-alone/eigrp-metric/ EIGRP Feasibility Condition: www.practicalnetworking.net/stand-alone/eigrp-feasibility-condition/
Hi! I belive, that you missed one important moment about Type 2 LSAs. When you using Ethernet ports on touter (and nowadays you will mostly use Ethernet) routers by default will treat this links as multiaccess, because they can't know do this link connects directly to another router, or there can be switch in beetwen and potentially multiple routers. So, if you only connect two routers by Ethernet link directly to each other - they will treat this link as multiaccess, chose DR and BDR and will send Type 2 LSAs. You need to explicitly configure this links as p2p.
Only a few days away from my CCNA, and your videos have helped explain some topics I was murky on after jeremy & david B's courses. You dont have a Security+ course do you?
So glad you found these helpful, Huy. Cheers =) If you're willing... Could you do me a favor? Do you mind sharing this video on Linked In, Reddit, Twitter, Facebook, or any other social media you use? As an independent creator, that would be an _enormous_ help, and I would appreciate it _greatly_ .
@ 2:52, if R2 and R3 are then configured with OSPF, would not Hello Packets, DBD, LSR, ... to form adjacency have happen? The forming of the adjacencies must take place with R2 and R3 before L1's can be sent. I can see how LSU/LSAs would be sent upstream from R1, or after adjacencies have already formed. Could you tell me what I am missing? What is the transition from creating full adjacencies between two OSPF routers and when LSA types begin to fully operate. Thanks!
Yes, all that would still happen. I'm simplifying that out in this video to focus on LSAs. But everything else in the series still applies (hello packets, LSU/LSR/LSA/DBD, neighbor adjacency sequence, and so on)
Many thanks. One question about example with 3 Routers R1,R2,R3 starting approx at 2:30, you mention that there's only 1 LSA type 1 per router (and update if necessary). When R3 emits its LSA type 1, in order for R2 to be aware of R3 update, I guess R1 propagates the update with a LSU (?), is it correct ? i am confused for now, with the propagation mechanism in order for all routers in area 0 to have the same LSDB.
Have a doubt at 11th minute of the video about type 4 LSA, R6 will introduce it to R4 by type 1 LSA, and these will be shared to area 0 via R2 as type 3 LSA, so Routers in R1 will knows about R6 right?
Why is R6’s Type 1 LSA / subnet that is sent to R4 not then sent to area 0 / R1 by R2 via a Type 3 LSA (if a type 3 is summarizing all the Type 1&2’s sent within its area) at which point it would know how to reach R6 when trying to get to the external subnet?
@10:56, it is stated that R6 has introduced itself into Area-44 using a Type-1 LSA. I am missing something here. Are we assuming that R4 and R6 are already neighbors? If so, how does this introduction happen?
Yes, they are already neighbors. The implication is that all routers in the same areas have become neighbors because of their Type 1 LSAs. Of course, normally they would be sending hello packets and validating various attributes, but for this video I'm simplifying and saying all routers in the same area are neighbors.
No sure to understand why there is no TYPE 2 LSAs on the 2 segments between R1and R2, and between R1 and R3 since there is also a DR on each link (this after minute 4). Arent these also multi-access links?
Hi Ed I don't get why we need type 4 LSA. When router R6 introduced it self in area 44 via type 1 LSA should the ABR router R2 have sent type 3 LSA including subnet 9.9..9.0/24 in the summary into area 0? so every routers how to reach R6.
So if a ASBR router introduces with Type 1 LSA to area 44. Why doesn't that type 1LSA get summerised within Typer 3LSA together with all of the other type 1 and 2 LSA's? Type 4LSA would seem like a owerhead. Im sure im missing some critical detail, can anyone explain?please
It's not the LSA itself that gets summarized by a Type 3. It's the _content of the LSA_ (in particular, the IP Networks contained in the LSA) that gets summarized by the type 3. Type 3 LSAs do not contain any information about the routers in foreign areas.
Yes! If you're building the topology, any of the routers on the multi access segment could be the DR (R2/R7/R8/R9). Itw ill be whichever router wins the DR election (or is the first to be stood up). Details in the DR video: ua-cam.com/video/Mi3tNSUjb78/v-deo.html
If you say that the internal routers are representative of any number of internal routers, how about the ABRs? I've watched several intros to OSPF and they all use just a single ABR between areas which immediately makes be wonder about redundancy. I mean isn't this one of the main reasons to use a routing protocol, resilience to hardware (link or router) failures?
I still don't understand why they created LSA5. They could use LSA1 that ASBR generates anyway to spread external routes. Just put all the external routes that you got via redistribution inside LSA1 and it's done. And you can spread them as normal LSA1. Instead of that they created LSA5 and when they realised that it was unreacheble they also created LSA4. I don't understand. I think I miss something. It looks like for me that they just didn't want to change LSA1. It was simpler to add a couple of more LSAs to handle external routes.
📌 *More free preview lessons from the Practical OSPF course:* pracnet.net/ospf
📌 *Want even more? Check out the full course:* pracnet.net/ospfcourse
📌 *CCNA Resources:* pracnet.net/ccna
📌 *Learn Networking:* pracnet.net/nf
📌 *Learn & Practice Subnetting:* subnetipv4.com
Ed, you're a bit of a savant. I will never understand how you can have such a grasp of all of this. Your instruction is fantastic, I will have to review this when I'm not half asleep, but what you share with us is AMAZING.
Thanks for the kind words, Scott =). Yes, definitely let us know what you think when you get back to this video. Cheers !
Dude, you are one of a kind, man. I mean, YOU EXPLAINED IT AMAZING!
Glad it helped =)
I want to say thank you, I am bluffed by how you have explained that, I have purchased many of CCNA & CCNP courses, but no one has explained it the way you did.
Thank you
The diagram you made to help explain this is excellent!
Best explanation I have come across so far! Thanks for the great work.
You're very welcome, Ale. Cheers.
I have been searching for almost 7 years to know what is the LSA Types differences and their nonsense theory and you nailed it in a shot.
Superb.
It feels like no instructor knows what exactly LSA's are except you.
Watching OSPF topics on your channel. One of the Best teacher. You are awesome in conveying the information with pictorial form.
Perfect explained LSA Types 1,2,3,4,5
Thank you, Gokhan =)
Sorry to be that person but there are actually 11 types of LSAs (OSPF).
LSA Type 1 Router LSA
LSA Type 2 Network LSA
LSA Type 3 or 4 Summary LSA & ASBR LSA
LSA Type 5 Autonomous System External LSA
LSA Type 6 Multicast OSPF LSA Type
LSA Type 7 Defined for Not-So-Stubby-Areas
LSA Type 8 External Attribute LSA for BGP
LSA Type 9,10,11 Opaque LSA
RFC 5250 back in 2008 discusses these. Cisco, one, it not the largest, vendor which many people are familiar with, only supported 1-5 for the longest but other vendors supported OSPF LSAs (6-11) well before especially with the advent of Traffic Engineering (10-11 "Opaque" LSAs). Very good explanation on the 5 types you discussed here.
I did say the 5 "main" types of LSAs at the start of this video ;)
Amazing content. The slide designs are appealing to the eyes. And your exploitation is good.
Your explanation of LSA types is trully best, as you promised in description!
Glad you enjoyed it, Tonic. Thank you for the kind words.
Excellent work and clear explanation. Thank you.🤓
Thank you so much for supporting the channel, Yasa =) I'm thrilled to hear you enjoyed this content.
excellent presentation. Thanks!
Your videos are simply the best I have come across. Rich in content and details
Thank you for the kind note, Idowu. Glad you have enjoyed this content.
A passed my CCNA yesterday!! Thank you for the videos, they really helped
Wohooo! Congratulations Chantelle! Huge achievement =).
Saying Thank you is a very least. I really have cleared many doubts through your content.
Absolutely amazing how you explain this topic
Glad you enjoyed it, David.
All of your videos are presented with such a great explanation and animation that it makes confusing concepts very clear, very quickly. Thanks!
Thank you very much.
I really appreciate your explanation with moving diagrams.
I currently prepare myself for an exam and it was really hard for me to imagine how it works just out of the slides.
Before this video I didn't even understand where the LSA are all send to.
You are such a legend. Makin everything so easy to understand! Thank you =]
You're very welcome, Hampus.
The content is o rich. I watched the video and helped me a great deal. thanks you are awesome
best ospf lessons! thank you
This is the best video I have seen about LSA's in a simple understandable way!
Thanks alot for this understanding session sir it's so awesome..... thanks alot sir
Mind Blown!!! its like a clog in my brain has melted due to this OSPF LSA types
Fantastic! Glad this video helped !
Great presentation. You simplified every thing .thanks
You're welcome, Samuel !
simply amazing
Extensive explanation in a brief way 🫶
WOW. Best content I've run across. Greatly appreciate your style.
Thank you very much, such an amazing explanation
Thank you for your great work, just one remark regarding type 4/5 LSA, you mentioned that router 6 (which is an ASBR) introduced itself to router 4 by type 1 LSA, assuming that this type 1 LSA will be forwarded by the ABR R2 as a type 3 LSA to other areas, so other areas will know about R6, so there will be no need for Type 4 LSA as a helper for this redistributed type 5 LSA !!
>> assuming that this type 1 LSA will be forwarded by the ABR R2 as a type 3 LSA
This isn't entirely correct. The actual Type 1 LSA will not be forwarded. Instead, only specific information from _within_ the Type 1 LSA is forwarded -- specifically _only the IP Subnets contained in the Type 1 LSA are forwarded._ The Routers identity (which is included in Type 1 LSAs) is not included in the Type 3 LSAs.
To really understand it, I'd recommend the LSA Deep DIve videos:
Type 1 & 2: ua-cam.com/video/1FOBkIoDbCc/v-deo.html
Type 3: ua-cam.com/video/8fFtU5W9WGk/v-deo.html
Thanks for both contributions. I'd like to make a remark about LSA type 5 that originates from an external non-OSPF domain in an NSSA area. Shouldn't it be converted from type 7 to type 5?
Ed ..Fabulous.. you are my favorite trainer along with jeremy it's lab
Thank you, Devanand =). Cheers !
Wow just wow.
These videos helped me to get into one of the MAMAA companies. Thanks to you.
Please please make similar videos on BGP.
Whoa that's awesome! Congratulations! Which one?
BGP is on my list, at some point I'd love to get to it. But no imminent plans.
You've mad something quite confusing very understandable. Thank you.
You're very welcome, James.
finally an explanation that stick to my mind. tnx
Awesome, glad this helped =)
Love it, short summary of lsa
Brilliant. You explain these topics so well. Thank you.
Another great tutorial. Wish to learn advanced BGP and Eigrp from you.
Noted about BGP, Randy.
As for EIGRP, I wrote three EIGRP articles you might enjoy:
EIGRP Explained : www.practicalnetworking.net/stand-alone/eigrp-terminology/
EIGRP Metric : www.practicalnetworking.net/stand-alone/eigrp-metric/
EIGRP Feasibility Condition: www.practicalnetworking.net/stand-alone/eigrp-feasibility-condition/
Hi! I belive, that you missed one important moment about Type 2 LSAs. When you using Ethernet ports on touter (and nowadays you will mostly use Ethernet) routers by default will treat this links as multiaccess, because they can't know do this link connects directly to another router, or there can be switch in beetwen and potentially multiple routers. So, if you only connect two routers by Ethernet link directly to each other - they will treat this link as multiaccess, chose DR and BDR and will send Type 2 LSAs. You need to explicitly configure this links as p2p.
Correct! That is explained in the Type 1 & Type 2 deep dive video:
ua-cam.com/video/1FOBkIoDbCc/v-deo.html
=)
Thank's a lot for your time man! your are really helpful!
Thanks for the explanation it was really helpful!
I can't thank you enough for this clear and brief lecture. That was fantastically done!
Thank you !
It is helpful as I am currently preparing for CCNA. So I am gonna jump to the Type1 and 2 LSA video of yours:) Thanks a lot
You made a magic in 14 Minute....Great Man
seriously appreciate your videos, wish I had found you before I payed for other courses...
Only a few days away from my CCNA, and your videos have helped explain some topics I was murky on after jeremy & david B's courses. You dont have a Security+ course do you?
Thanks a ton, very succinct explanation :)
thanks you
Amazing! Very good one!
Good stuff! Thanks for putting the work in to share this info. Very helpful
Glad you enjoyed it =).
Yes, this is indeed the best explanation.
awesome thanks for explaining
So helpfull
great explanation
Great explanation ...
Greate explanation about the LSAs. Thanks
That was really the BEST explanation. Thank you.
Good explanation!
great clarification!
Excelent explanation about LSA
Thanks for easy explanation
You're welcome !
Incredibly well explained. Ty!
nice explanation
Just amazin'!
;)
I really really appreciate your work. Keep it up please. You helped me so much....
So glad you found these helpful, Huy. Cheers =)
If you're willing... Could you do me a favor? Do you mind sharing this video on Linked In, Reddit, Twitter, Facebook, or any other social media you use? As an independent creator, that would be an _enormous_ help, and I would appreciate it _greatly_ .
@@PracticalNetworking Since I use facebook, I will help you share it on this platform :)))
@@huyvuquang2041 Thank you for your support, Huy =)
Marvelous ❤❤❤ Brother
Absolutely amazing
you awsome man .
Excellent explanation!
Glad you enjoyed it, Weber =)
Nicely done thank you so much for your time.
You're welcome. Glad you enjoyed it =)
@ 2:52, if R2 and R3 are then configured with OSPF, would not Hello Packets, DBD, LSR, ... to form adjacency have happen? The forming of the adjacencies must take place with R2 and R3 before L1's can be sent. I can see how LSU/LSAs would be sent upstream from R1, or after adjacencies have already formed. Could you tell me what I am missing? What is the transition from creating full adjacencies between two OSPF routers and when LSA types begin to fully operate. Thanks!
Yes, all that would still happen. I'm simplifying that out in this video to focus on LSAs. But everything else in the series still applies (hello packets, LSU/LSR/LSA/DBD, neighbor adjacency sequence, and so on)
Thanks so much!
This is a great lesson, Thank you.
Good explanation. You might have had a typo on you ASBR. Instead of "Boundary" you used "Border"
Great explanation.
Thank you, Azza.
Well explained! do you have deep dive in EIGRP?
I have three articles on my blog that covers most of what most people need to know about EIGRP.
Many thanks. One question about example with 3 Routers R1,R2,R3 starting approx at 2:30, you mention that there's only 1 LSA type 1 per router (and update if necessary). When R3 emits its LSA type 1, in order for R2 to be aware of R3 update, I guess R1 propagates the update with a LSU (?), is it correct ? i am confused for now, with the propagation mechanism in order for all routers in area 0 to have the same LSDB.
Yes. Correct. After Routers are already neighbors with each other, they just send LSU's with new / updated info when necessary
Well done
Brill Sir just Brilllllllllllllllllllllllll
Have a doubt at 11th minute of the video about type 4 LSA, R6 will introduce it to R4 by type 1 LSA, and these will be shared to area 0 via R2 as type 3 LSA, so Routers in R1 will knows about R6 right?
AMAZING ❤
Why is R6’s Type 1 LSA / subnet that is sent to R4 not then sent to area 0 / R1 by R2 via a Type 3 LSA (if a type 3 is summarizing all the Type 1&2’s sent within its area) at which point it would know how to reach R6 when trying to get to the external subnet?
@10:56, it is stated that R6 has introduced itself into Area-44 using a Type-1 LSA. I am missing something here. Are we assuming that R4 and R6 are already neighbors? If so, how does this introduction happen?
Yes, they are already neighbors. The implication is that all routers in the same areas have become neighbors because of their Type 1 LSAs.
Of course, normally they would be sending hello packets and validating various attributes, but for this video I'm simplifying and saying all routers in the same area are neighbors.
Thanks! @@PracticalNetworking
thank you!!
Thank you
You're welcome.
What an explanation ... by the way I'm from India. Could you please tell me the simple definition of a domain ? I'm not getting it.
No sure to understand why there is no TYPE 2 LSAs on the 2 segments between R1and R2, and between R1 and R3 since there is also a DR on each link (this after minute 4). Arent these also multi-access links?
superb!
Hi Daniel, thank you for supporting the channel =) Glad you enjoyed the video!
Hi Ed I don't get why we need type 4 LSA. When router R6 introduced it self in area 44 via type 1 LSA should the ABR router R2 have sent type 3 LSA including subnet 9.9..9.0/24 in the summary into area 0? so every routers how to reach R6.
OSPF's professor
;)
So if a ASBR router introduces with Type 1 LSA to area 44. Why doesn't that type 1LSA get summerised within Typer 3LSA together with all of the other type 1 and 2 LSA's? Type 4LSA would seem like a owerhead. Im sure im missing some critical detail, can anyone explain?please
It's not the LSA itself that gets summarized by a Type 3. It's the _content of the LSA_ (in particular, the IP Networks contained in the LSA) that gets summarized by the type 3. Type 3 LSAs do not contain any information about the routers in foreign areas.
Gooooood woooooorrrkkkk👏👏
Thank you =)
Fcking brilliant explanation. Smthing my lector failed to do so.
Passed the ccna
WOHOOO! Congratulations!
4:02 can R2 be a DR ? because it just happened in my GNS3 LAB
Yes! If you're building the topology, any of the routers on the multi access segment could be the DR (R2/R7/R8/R9). Itw ill be whichever router wins the DR election (or is the first to be stood up). Details in the DR video: ua-cam.com/video/Mi3tNSUjb78/v-deo.html
If you say that the internal routers are representative of any number of internal routers, how about the ABRs? I've watched several intros to OSPF and they all use just a single ABR between areas which immediately makes be wonder about redundancy. I mean isn't this one of the main reasons to use a routing protocol, resilience to hardware (link or router) failures?
gread vid
Thank you =)
I still don't understand why they created LSA5. They could use LSA1 that ASBR generates anyway to spread external routes. Just put all the external routes that you got via redistribution inside LSA1 and it's done. And you can spread them as normal LSA1. Instead of that they created LSA5 and when they realised that it was unreacheble they also created LSA4. I don't understand. I think I miss something. It looks like for me that they just didn't want to change LSA1. It was simpler to add a couple of more LSAs to handle external routes.
❤