From: Chris Lewis \(chrlewis\) (chrlewis@cisco.com)
Date: Fri Jul 08 2005 - 11:47:05 GMT-3
This is possible, if I understand the question correctly, however care
is needed in how the loopbacks are injected into OSPF.
So if the goal is to get R3 with a single summary route covering the
10.1.12.8/30 and the 10.1.12.1/32, but also a more specific for
10.1.12.5, this is how I would do it.
First a summary route to cover that range needs to be 10.1.12.0/28,
which I would create using the area range command. This will only
summarize internal OSPF routes. You still want the specific for loopback
1 to get through, so inject that in to OSPF via redistribution, so it is
not summarized by the area range command. Routing table for R3, followed
by relevant config for R1 and R2 follow:
Berore any summarization, R3 has a routing table like this
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
O E2 10.1.12.4/30 [110/20] via 10.1.13.1, 00:00:55, Serial3/0
C 10.1.13.0/30 is directly connected, Serial3/0
O IA 10.1.12.1/32 [110/129] via 10.1.13.1, 00:05:29, Serial3/0
O IA 10.1.12.8/30 [110/128] via 10.1.13.1, 00:21:21, Serial3/0
After the area range command is applied on R2, R3 has a routing table
like this.
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O E2 10.1.12.4/30 [110/20] via 10.1.13.1, 00:03:09, Serial3/0
C 10.1.13.0/30 is directly connected, Serial3/0
O IA 10.1.12.0/28 [110/128] via 10.1.13.1, 00:00:13, Serial3/0
Is this what you were looking for?
R1:
!
interface Loopback0
ip address 10.1.12.1 255.255.255.255
!
interface Loopback1
ip address 10.1.12.5 255.255.255.252
!
router ospf 1
log-adjacency-changes
redistribute connected subnets route-map conn
network 10.1.12.1 0.0.0.0 area 1
network 10.1.12.9 0.0.0.0 area 1
!
access-list 1 permit 10.1.12.4 0.0.0.3
!
route-map conn permit 10
match ip address 1
R2:
router ospf 1
log-adjacency-changes
area 1 range 10.1.12.0 255.255.255.240
network 10.1.12.8 0.0.0.3 area 1
network 10.1.13.0 0.0.0.3 area 0
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Teesa Peter
Sent: Friday, July 08, 2005 12:56 AM
To: ccielab@groupstudy.com
Subject: OSPF Summarization
Hi group,
I just thought of this situation but didn't find any solution.
R1--------------R2-------------R3
R1---R2 subnet is
10.1.12.8 255.255.255.252
R2---R3 subnet is 10.1.13.0 255.255.255.252 R1's loopback 0 is
10.1.12.1 255.255.255.255
R1's loopback 1 is
10.1.12.5 255.255.255.252
R1--R2 link and R1's loopbacks area on Area 1.
R2--R3 link is Area 0
I want to summarise Area 1 subnets into area 0 to a single route, along
with specific route of R1's loopback 1 .ie only 10.1.12.8 & 10.1.12.1
should be summarised.Is it possible ?
If I configure area
1 range command then all the three subnets will be summarised ,How can I
exclude loopback 1 being summarised ?
If I configure area filter-list
then how can I generate the summary route ?
Or if there is any other way
of accomplishing this ?
Thanks,
Peter
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