From: YourPal (dearprudence28@gmail.com)
Date: Tue Jan 22 2008 - 01:19:52 ARST
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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