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L4 Transporter

OSPF question

I have a stub area - my office.

But I have 2 paths into it from area 0.0.0.0

Is it still a stub as its has 2 paths in and out.

 

so area 0.0.0.0 via rtr A to area 10.172.0.0 or area 0.0.0.0 via rtr b to area 10.172.0.0

 

What I want it just the DGW sent it from both rtrA and rtrB


Accepted Solutions
Highlighted
L7 Applicator

Re: OSPF question

@Alex_Samad,

So a stub area by default will allow LSA types 1,2, and 3; while a Totally Stubby Area is only going to allow LSA types 1,2, and the default route that you actually want. You can also create a Totally Not So Stubby Area if you have a requirement for redistribution, but it doesn't sound like you do with the information that you've provided. 

Totally Stubby Areas are stub areas with an additional option bit for the vast majority of switch/routing vendors. Very few actually allow for a straight Totally-Stubby declaration. The vast majority of equipment you're simply specifying an additional parameter like no-summaries in junos or  no-summary in Cisco terminology.

 

How you would actually get this configured is going to depend on your equipment vendor, but pretty much every vendor I've ever run across will have detailed configuration examples on how to configure Totally Stubby Areas, that's a pretty universal phrase. 

View solution in original post


All Replies
Highlighted
L7 Applicator

Re: OSPF question

@Alex_Samad,

I'm a little lost on your question and what you are trying to achieve. If this was a stub area properly configured to begin with, redundant paths aren't going to make it not a stub; that's actually how the vast majority of networks would be configured. 

L4 Transporter

Re: OSPF question

So I have my office it has 2 routers A + B

 

A connects to DC A and B connects to DC B

 

DC A + DC B are connected.

 

Is the office is a stub area, a packet can leave the area via a different routers than it entered into from.

 

Curently all of the OSPF DB is sent into the area. If I can change it to a stub area only 0.0.0.0 will be sent it

Highlighted
L7 Applicator

Re: OSPF question


@Alex_Samad wrote:

so area 0.0.0.0 via rtr A to area 10.172.0.0 or area 0.0.0.0 via rtr b to area 10.172.0.0


If you only want a default route to be propagated, then it sounds more like you actually want to use a totally stubby area instead of a stub area. If you configure this as a stub area you'll still going to get all of the routes within the OSPF network, the only thing a stub area is going to do is block type 5 LSAs.

If you create a totally stubby area you'll block type 5 and type 3 LSAs and the only route you'll get is the actual default route that you want; the only exception to this is if you continue to utilize the same 10.172.0.0 area for this connection. 

 

I'm not trying to come off as rude or anything, but before you actually do this I would recommend reading up on OSPF and area configurations. It sounds like right now you are using a very simple single area network, and that works fine for a lot of networks. Decide if you actually need to separate things into different areas, and then sit down and go through your area design before you actually do any of the actual configuration.

 

Highlighted
L4 Transporter

Re: OSPF question

I'm happy to be called out if I am missing something

 

and I do a lot of reading, but I look at OSPF infrequently  - so there is some stuff you learn by doing it day in day.

 

Which is why I come to forums.

 

As for totally stub and stubb. do you mean stub and not so stubby ?

 

stub & nssa 

 

A

Highlighted
L7 Applicator

Re: OSPF question

@Alex_Samad,

So a stub area by default will allow LSA types 1,2, and 3; while a Totally Stubby Area is only going to allow LSA types 1,2, and the default route that you actually want. You can also create a Totally Not So Stubby Area if you have a requirement for redistribution, but it doesn't sound like you do with the information that you've provided. 

Totally Stubby Areas are stub areas with an additional option bit for the vast majority of switch/routing vendors. Very few actually allow for a straight Totally-Stubby declaration. The vast majority of equipment you're simply specifying an additional parameter like no-summaries in junos or  no-summary in Cisco terminology.

 

How you would actually get this configured is going to depend on your equipment vendor, but pretty much every vendor I've ever run across will have detailed configuration examples on how to configure Totally Stubby Areas, that's a pretty universal phrase. 

View solution in original post

Highlighted
L7 Applicator

Re: OSPF question

Hello,

I understand that you only want the default route broadcast into the area, but any reason why? Since you only have a few sites, the firewalls/routers should be able to handle a few routes. I more than twice what you have any just found it easier to set everything into area 0.0.0.0 and user weights and route distribution to send out what is needed to the far site.

 

Hope that makes sense.

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