OSPF NSSA (Not so stubby area)

i visit every day this and do lab now admin might delete all lab config file pls share all lab solution config file again it really helps to learn the concept well hope you do this again for all lab i am waiting for that

I'm doing the best i can to add final configs for all labs, it's very time consuming so i'm not sure when i'll be able to do so.

I believe however that working yourself to the final solution will learn you more than just checking on the answer file

Good luck!

Rene

Hey, thanks a lot. Very nice work. Just some remarks
"Advertise these networks into OSPF, do not use the "network" command to achieve this!"
Me personally - I did it using ip ospf 1 area 3 under interface lo1 and interface lo2 sub-menus

Therefore - that makes impossible completing the next task : "Router Thor: configure a summary towards Area 0 for the 2 loopbacks you just created,"
by using summary-address command, since those routes aren't external. therefore - I did it on Router Wodan, which is an ABR, by using area 3 range... command.

Correct me if i'm wrong

That'll do the trick as well. I like to use tasks like "don't use this or that command" so you have to think about other options. There are two ways of getting something into the OSPF Database and that's advertising (using the network or interface) command OR redistribution.

Both will do the trick but you have to be careful with other tasks, good job though!

Using "redistribute static" command you could make a summary on the router Thor for these external routes.

With OSPF there are 2 ways to summarize:

- Type 3 summary LSAs (inter-area) by using the summary command.
- Type 5 external LSAs by using the area range command.

i did this lab and i thought in use too the "ip ospf" command under interface config mode.So the problem is that once you use that command the loopback interfaces become advertised into internal ospf areas so to summarize properly i can use only "area range" command on router Wodan. So the lab was asking to summarize on router Thor so i dont think i did correct.

Wow i am glad you posted up solutions for these labs. Makes it great for all of us to learn HOW to solve them, just not making scenarios.

Glad you like it william.

Hi mcox50,

Thanks for your message. let me give you my answer on this:

The way I state the task/goal/questions is the way another network engineer or a customer could ask you a question. I'm not going to tell you "type in area X summary" command, which would be nothing more but copy/pasting. It's up to you as a network engineer to find out what command you should use to summarize inter-area prefixes. If you don't know the command you can look them up in my final configuration.

If you look at the task before the one where you have to summarize you can see it says "Advertise these networks into OSPF, do not use the "network" command to achieve this!"

If you are not allowed to use the "network" command you can only use the "redistribute" command. Once again i'm not going to tell you as a task "type in redistribute X" but I'm trying to make people think what other methods there are to put something into a routing protocol besides using a "network" command. I believe this makes the difference between learning something and "monkey see monkey do".

When summarizing with OSPF you have to summarize inter-area routes with the summary-address command (LSA TYPE 3). External routes (LSA TYPE 5) have to be configured using the area range command. Two different things, two different commands.

When I started the site I took the idea of using funky router names from the book "Routing TCP/IP Vol1"...which is about the best and most complete routing book you could get. It would have been much easier to use R1,R2,R3 and such and if I had to redo everything I probably would...now i'm going to stick with it.

Networking isn't a toy but things don't have to look professional/serious to be professional all the time...We are learning here which should be fun. No need to sit in a suit and tie behind the computer configuring routers here.

Good luck with the labs and thanks for your comment!

hi,
the labs are good, but your main problem is language, the way you ask tasks to do is not clear, for exemple you said:

Router Thor: configure a summary towards Area 0 for the 2 loopbacks you just created, make sure you do not advertise networks you do not have.

Your solution shows that you used summary-address ...command

and same question for Zeus Router:

Router Zeus: configure a summary towards Area 0 for the 2 loopbacks you just created, make sure you do not advertise networks you do not have.

You used area range ... command...

it's somehow confusing, why you used the question format and you configured it as summary-address then you asked the same question for zeus router and you solved it with area range ... i don't understand..;

In addition, why you are using names like thor, godzila, zeus ... this is not professional, it makes me feel like if i'm playing with toys and kids.... Sorry but i suggest to change the names for normal Routers names R1 R2 R3 etc so people do not get confused.

Thank you.

"When summarizing with OSPF you have to summarize inter-area routes with the summary-address command (LSA TYPE 3). External routes (LSA TYPE 5) have to be configured using the area range command. Two different things, two different commands."

I think its the other way around.

Anything that is local to the OSPF domain is summarized by using the area range command and anything that is from a outside source with the summary-address command.

In our case Wodan sees the 172.16.0.0 and 172.16.1.0 subnets as N2 - OSPF NSSA external type 2(type 7 LSAs) and Zeus sees them as E2(type 5 since they passed through Wodan and it converted them).

Using area range will not work since this came from a outside source(redistribution on Thor) so Wodan does not create summary route and Zeus still sees E2 routes.

The correct way to do it in this case is summary-address on either Thor or Wodan.

As a rule of thumb:
ABR - area range command to summarize
ASBR - summary-address to summarize

Hi Alexandru,

Thanks for your comment on the area range vs summary-address. You are totally right...I always mix those up ;D Just edited my comment.

Rene

This lab was cool.
thanks again for creating this.

your welcome!

Interesting video but could you tell about when advertising 172.16.2.0 and 172.16.3.0 network of zeus why did you use 'network 172.16.0.0 255.255.0.0 area 4' instead of 172.16.0.0 0.0.255.255 area 4 command under ospf? I'm confused in this bit.

cheers

Did I type 172.16.0.0 255.255.0.0 area 4? If so I've been sleeping OSPF requires wildcards but if you accidently type in a subnet mask it will convert it to a wildcard...try it and you'll see.