From: Bit Gossip (bit.gossip@chello.nl)
Date: Sun Aug 26 2007 - 13:21:14 ART
Hi Lim,
the lab seems to confirm the area X range on an ABR creates a summury LSA
out of all and ONLY intra area X routes, so only native ospf routes of area
X. This doesn't include external and inter-area (LSA type 3).
R1--- area 1---R2---area 0---R4---area 170 (170.1.170.170/32)
R2(config-router)#do show run | b router ospf 1
router ospf 1
router-id 170.1.2.2
area 0 range 170.1.0.0 255.255.0.0
As you can see on R1 both external and IA (170.1.170.170) leaks to the area
0 range because not originated in area 0
R1#show ip route ospf
170.1.0.0/16 is variably subnetted, 10 subnets, 6 masks
O E2 170.1.200.0/27 [110/20] via 170.1.150.2, 00:00:01,
FastEthernet1/0/13
O E2 170.1.15.0/26 [110/20] via 170.1.150.2, 00:00:01, FastEthernet1/0/13
O IA 170.1.170.170/32
[110/658] via 170.1.150.2, 00:01:08, FastEthernet1/0/13
O E2 170.1.9.9/32 [110/20] via 170.1.150.2, 00:00:01, FastEthernet1/0/13
O E2 170.1.7.7/32 [110/20] via 170.1.150.2, 00:00:01, FastEthernet1/0/13
O IA 170.1.0.0/16 [110/11] via 170.1.150.2, 00:00:06, FastEthernet1/0/13
O E2 170.1.69.2/32 [110/20] via 170.1.150.2, 00:00:02, FastEthernet1/0/13
I could not find any confirmation on the DocCD related to this behavior,
maybe someone else has more luck ....
Bit.
----- Original Message -----
From: "Toh Soon, Lim" <tohsoon28@gmail.com>
To: "Serhat Aslan" <serhatworks@gmail.com>
Cc: "Cisco certification" <ccielab@groupstudy.com>
Sent: Sunday, August 26, 2007 4:35 PM
Subject: Re: OSPF "area range" command summarizes only intra-area routes?
> Hi Serhat,
>
> I'm sorry I don't fully understand your points.
>
> Without any area summarization, routers in Area 4 will learn all the
> 200.0.0.x/32 routes as inter-area routes.
>
> I want to summarize all these host routes so that routers in Area 4 only
> see
> 200.0.0.0/24. I did it on the ABR (R4) using the "area 0 range 200.0.0.0
> 255.255.255.0" command.
>
> However, Area 4 still sees 200.0.0.9/32. Why? As far as R4 is concerned,
> the
> 200.0.0.9/32 is an inter-area route whereas the other 200.0.0.x/32 are
> intra-area routes.
>
> Appreciate your further advice.
>
>
> Thank you.
>
> B.Rgds,
> Lim TS
>
>
> On 8/26/07, Serhat Aslan <serhatworks@gmail.com> wrote:
>>
>> Hi Toh,
>> You made a wrong summarization. The steps of the summarizations are:
>> 0. The areas must be originated with the specified ABR. This means
>> intra-area routes.
>> 1. Choosing an Area, (the routes must be originated with the same area)
>> "area-range X"
>> 2. Area Routes Aggregation, (IP subnet mask supernetting)
>>
>> You forgot to consider step1.
>>
>> Serhat Aslan
>>
>>
>> On 8/26/07, Toh Soon, Lim <tohsoon28@gmail.com> wrote:
>>
>> > Hi Group,
>> >
>> > R4 is an ABR connected to Area 0 and Area 4. It learns the following
>> > routes
>> > in Area 0:
>> >
>> > Intra-area:
>> > 200.0.0.2/32
>> > 200.0.0.5/32
>> > 200.0.0.6/32
>> >
>> > Inter-area:
>> > 200.0.0.9/32
>> >
>> > I'm trying to summarize the above routes into Area 4, as follows:
>> >
>> > !
>> > router ospf 1
>> > area 0 range 200.0.0.0 255.255.255.0
>> > !
>> >
>> > Routers in Area 4 see the summary address 200.0.0.0/24. All component
>> > routes
>> > are suppressed except for 200.0.0.9/32 which "leaks" into Area 4. E.g.
>> >
>> > O IA 200.0.0.9/32 [110/784] via 192.168.40.1, 00:21:02,
>> > FastEthernet0/0
>> > O IA 200.0.0.0/24 [110/2] via 192.168.40.1, 00:17:49,
>> > FastEthernet0/0
>> >
>> >
>> > I suspect the "area range" command only summarizes intra-area routes.
>> > Can
>> > anyone clarify this? I might be missing something here.
>> >
>> >
>> > Thank you.
>> >
>> > B.Rgds,
>> > Lim TS
>> >
>> > _______________________________________________________________________
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>> > http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
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