From: YourPal (dearprudence28@gmail.com)
Date: Sat Jan 19 2008 - 13:50:03 ARST
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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