Re: OSPF LSA type 3 filtering

You guys don't mind me adding a thing or two to otherwise great
technical discussion (excluding those other bits).

> The next is where the distinction is made, as area 1 in would affect routes
> going out of area 0 and area 2 into area 1, but would not affect routes going
> out of area 0 into area 2, and likewise it would not affect routes going out
> of area 2 into area 0.

In IOS, there is no direct summarization between non-backbone areas.
I.e. the only direction for LSA summarization is 0->other and
other->0, but there is no other->other. However, when discussing OSPF,
it's important to keep in mind that not all vendors do things the same
way.

Just to illustrate the above point, what makes a router an ABR? Here's
my take on implementation by Cisco IOS and Juniper Junos:

http://blog.ipexpert.com/2012/05/10/what-makes-a-router-an-ospf-abr-cisco-and-juniper-comparison/

Great stuff. We should have more these technical discussions here. I
miss 'em :-)

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor - IPexpert
Blogs and organic groups at http://www.ccie.net