Tuesday, December 7, 2010

Connecting Two OSPF Areas With Stub Area In Middle Challenge - Diagram & Initials


###################
# Here are the Initials  #
###################

^^^ R1 ^^^
^^^^^^^^^^

en
!
conf t
!
ho R1
!
no ip do lo
!
line con 0
no exec-time
exit
!
int lo0
ip add 11.11.11.11 255.255.255.255
exit
!
int f0/0
ip add 12.12.12.1 255.255.255.0
no sh
exit
!
router ospf 1
router-id 255.255.255.1
net 11.11.11.11 0.0.0.0 a 0.0.0.0
net 12.12.12.1 0.0.0.0 a 0.0.0.1
area 1 stub
exit
!
end
!
wr mem
!
==================================

^^^ R2 ^^^
^^^^^^^^^^

en
!
conf t
!
ho R2
!
no ip do lo
!
line con 0
no exec-time
exit
!
int f0/0
ip add 12.12.12.2 255.255.255.0
no sh
exit
!
int f1/0
ip add 23.23.23.2 255.255.255.0
no sh 
exit
!
router ospf 1
router-id 255.255.255.2
net 12.12.12.2 0.0.0.0 a 1
net 23.23.23.2 0.0.0.0 a 2
area 1 stub
exit
!
end
!
wr mem
!
==================================

^^^ R3 ^^^
^^^^^^^^^^

en
!
conf t
!
ho R3
!
no ip do lo
!
line con 0
no exec-time
exit
!
int f0/0
ip add 23.23.23.3 255.255.255.0
no sh
exit
!
int lo0
ip add 33.33.33.33 255.255.255.0
no sh 
exit
!
router ospf 1
router-id 255.255.255.3
net 33.33.33.33 0.0.0.0 a 2
net 23.23.23.3 0.0.0.0 a 2
exit
!
end
!
wr mem
!
********************************

3 comments:

Anonymous said...

GRE can fix anything ;)

bookworm said...

Hello Deepak Ji,

I got a doubt on Tunnel participation in OSPF advertizement.

~~~~~~~~~~~~~~~~~~

R1(config)#router ospf 1
R1(config-router)#net 112.112.112.1 0.0.0.0 a 0
R1(config-router)#exit


R2(config)#router ospf 1
R2(config-router)#net 112.112.112.2 0.0.0.0 a 0
R2(config-router)#exit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In Router R2 why should we give "Area 0" here. Because R2 don't know about 'Area 0' till now right !

Please correct me where i am lacking or thinking in wrong direction.

Thanks a million in advance :)

/ Gangadhar

Deepak Arora said...

The area should match on both sides in order to form neighborship. That's fundamental rule for ospf in order to form adjacency.

I would suggest you to read following two posts and see if things make more sense.

In case you still feel issues...feel free to drop me an email or comment here.

http://deepakarora1984.blogspot.com/2010/10/things-that-must-match-in-order-to-form.html

http://deepakarora1984.blogspot.com/2010/08/gre-tunnels-unleashed-making-breaking.html


HTH...
Deepak Arora