OSPF-STUB AREA

[miracle_david@yahoo.com]

Hi,

Please consider the following scenario. R2: ABR R3: a router connected to R2 as the last router of area 2. I define R3 as stub & R2 as stub no-summary. Is this configuration correct?

Figure in Stub area section  "https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html?dtid=osscdc000283#t28"

[Georg Pauwen]

Hello,

what are you trying to accomplish ? Defining the area as stub keeps type 5 AS-external LSAs out, defining the area as totally stubby keeps type 3, 4 or 5 LSAs out and allows only the default summary route. So it is either one or the other.

[miracle_david@yahoo.com]

So, do u mean it's incorrect & impossible to make 1 router stub & the other stub no-summary? If u refer to the link above you'll see that CISCO itself has done it & it must be a big mistake.

[Georg Pauwen]

Hello,

I wasn't clear on what you are asking, I thought you were looking for the difference between stubby and totally stubby. I guess Guiseppe's post below explains it very well...

[Giuseppe Larosa · Accepted solution]

Hello miracle_david@yahoo.com ,

the command

area x stub no summary

is needed only on the ABR nodes between area x and area 0.

The internal routers of the area just need to declare area x stub.

In building the OSPF adjacencies the stub area flag is checked but there isn't another flag for totally stub area.

So your configuration is correct if you apply the command on all the ABR(0,x) nodes and make area x a totally stub area.

Note:

if you want to revert area x to a standard type on the ABR node you may need to use two commands

no area x stub no summary

no area x stub

as the first command just removes the no-summary option and the second one removes the stub attribute

Hope to help

Giuseppe