From: shiran guez (shiranp3@gmail.com)
Date: Tue Jan 22 2008 - 04:34:22 ARST
you need to summerize the loopbacks on R1 also as the virtual
link extend area 0 so If you draw this on paper you would see that R1
is another area 0 point of connection to R3 so it also advertise to area 1
and the area range command is advertising the summary to the other areas not
to area 0 so there will be a leak from R1 to R3 of the specific routes.
Draw the logical areas with the virtual link on paper and you will see what
I mean.
Just Rememeber *Virtual Link is area 0 logical link!
*
On Jan 22, 2008 5:19 AM, YourPal <dearprudence28@gmail.com> wrote:
> Hi Experts,
>
> Can someone provide insight into this issue?
>
>
> Thank you.
>
> BR,
> Emil
>
>
> On 1/19/08, YourPal <dearprudence28@gmail.com> wrote:
> >
> > Hi Group,
> >
> > I have the following OSPF area summarization issue:
> >
> > R4-----(area 0)-----R5-----(area 1)-----R3-----(area 1)-----R1-----(area
> > 2)-----R2
> >
> > R4's lo0 (150.1.4.4/24) and R5's lo0 (150.1.5.5/24) are in area 0. The
> > loopbacks are advertised as host route.
> >
> > R5 summarizes the two loopbacks using command "area 0 range 150.1.4.0
> > 255.255.254.0". R3 correctly sees 150.1.4.0/23 and not the specifics.
> >
> > A virtual link is then built between R5 and R1 to connect area 2 to the
> > backbone. R1 also has the command "area 0 range 150.1.4.0 255.255.254.0
> ".
> >
> > Now, R3 no longer sees the summary 150.1.4.0/23. Instead it sees the
> > specific routes 150.1.4.4/32 and 150.1.5.5/32. Why is it so?
> >
> > In contrary, if I summarize area 1 routes on R5 and R1 using "area 1
> range
> > ..." command, R4 correctly sees the summary route. There's no "leakage"
> of
> > specific routes.
> >
> > The above issue is overcome by not using virtual link but building a GRE
> > tunnel between R5 and R1 and including the tunnel interfaces in area 0.
> The
> > "area 0 range ..." command remains on R5 & R1.
> >
> > Appreciate if anyone can shed some light on the issue.
> >
> >
> > Thank you.
> >
> > BR,
> > Emil
>
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-- Shiran Guez MCSE CCNP NCE1 http://cciep3.blogspot.com http://www.linkedin.com/in/cciep3
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