From: Paul Cosgrove (paul.cosgrove@heanet.ie)
Date: Fri Apr 11 2008 - 18:57:10 ART
Thanks Inran,
You have tested and found that Type-3 default routes are denied by the
database-filter, so as you said the original problem cannot be easily
solved without default static routes (or another protocol) on the
spokes. This would apply to both stub and totally stub areas as they
cannot use any other type of default route. Since these routes are
originated by the hub router, your tests suggest that the statement in
Optimising Routing Protocols about database-filter only filtering
received LSAs does not always apply.
Ignoring Type-3 default routes (which your tests show do not work with
this command), there are two other ways that default routes could be
injected into OSPF hub and spoke: default routers could also be injected
as Type-5 routes into a normal area, or Type-7 routes into a NSSA area.
The book does not mention the area type and so I was wondering if the
behaviour it describes occurs in either of those. If not then the
statement in the book must be incorrect.
Paul.
Mohmmad, Imran wrote:
> Hi Paul,
>
> If I have the "default-information originate always" on ABR, still there
> will be no LSA advertisement including the default from ABR
>
> router ospf 10
> log-adjacency-changes
> area 45 stub no-summary
> network 10.10.10.3 0.0.0.0 area 45
> network 40.40.40.3 0.0.0.0 area 45
> network 192.168.30.3 0.0.0.0 area 0
> default-information originate always
> !
> A#sh run int se1/1
> Building configuration...
>
> Current configuration : 198 bytes
> !
> interface Serial1/1
> description ****Connected to B******
> ip address 40.40.40.3 255.255.255.0
> ip pim sparse-mode
> encapsulation ppp
> ip ospf database-filter all out
> serial restart-delay 0
>
> B#sh ip os database
>
> OSPF Router with ID (2.2.2.2) (Process ID 10)
>
> Router Link States (Area 45)
>
> Link ID ADV Router Age Seq# Checksum Link
> count
> 2.2.2.2 2.2.2.2 40 0x80000001 0x007291 2
> B#
> B#
> B#sh ip route ospf
> B#sh ip route ospf
>
> Imran
>
> -----Original Message-----
> From: Paul Cosgrove [mailto:paul.cosgrove@heanet.ie]
> Sent: Friday, April 11, 2008 2:44 AM
> To: Mohmmad, Imran
> Cc: nagendra kumar; atif raees; ccielab@groupstudy.com
> Subject: Re: OSPF Inra Area route filtering
>
> Hi Imran,
>
> Interesting. "Optimal routing design" discusses the two database filter
>
> commands with hub and spoke on pages 177/178. The section ends with:-
>
> "You can also originate a default route at the ABR using
> default-information originate instead of static routes at the
> remote-routers. The command ip ospf database-filter all out only
> filteres learned LSAs, not locally originated ones, so a locally
> generated default would still be sent to the remote routers"
>
> The preceding example in the book is a partial config which doesn't
> specify an area type. I wonder if the different behaviour is related to
>
> the LSA type of the default, which with the totally stub will have to be
>
> Type 3?
>
> Paul.
>
> Mohmmad, Imran wrote:
>
>> It will block the advertisement of all LSA from interface including
>>
> the
>
>> default.
>>
>> DS1/0--------S1/1RP
>> |
>> |
>> S1/0
>> A
>> |
>> |
>> /\
>> / \
>> / \
>> S1/0 S1/0
>> B C
>>
>> Router D, RP and router A S1/0 is in area 0 and the router A se1/1 and
>> s1/2 in area 45 with two different point to point links.
>>
>> Once we configured the area 45 as totally-stub the OIA SLA that we can
>> see on B and C is the default route and Router SLA for C link to
>>
> router
>
>> A
>>
>> A#sh run | sec router ospf
>> router ospf 10
>> log-adjacency-changes
>> area 45 stub no-summary
>> network 10.10.10.3 0.0.0.0 area 45 <Link to router C>
>> network 40.40.40.3 0.0.0.0 area 45<Link to router B>
>> network 192.168.30.3 0.0.0.0 area 0
>>
>>
>> B#sh ip os database
>>
>> OSPF Router with ID (2.2.2.2) (Process ID 10)
>>
>> Router Link States (Area 45)
>>
>> Link ID ADV Router Age Seq# Checksum Link
>> count
>> 2.2.2.2 2.2.2.2 569 0x80000001 0x007291 2
>> 3.3.3.3 3.3.3.3 663 0x80000004 0x00E2C9 2
>> 150.1.3.3 150.1.3.3 588 0x8000000B 0x00DD9C 4
>>
>> Summary Net Link States (Area 45)
>>
>> Link ID ADV Router Age Seq# Checksum
>> 0.0.0.0 150.1.3.3 677 0x80000001 0x003769
>>
>> B#sh ip route ospf
>> 10.0.0.0/24 is subnetted, 1 subnets
>> O 10.10.10.0 [110/128] via 40.40.40.3, 00:02:59, Serial1/0
>> O*IA 0.0.0.0/0 [110/65] via 40.40.40.3, 00:02:59, Serial1/0
>>
>> A#sh run int se1/1
>> Building configuration...
>>
>> Current configuration : 198 bytes
>> !
>> interface Serial1/1
>> description ****Connected to B******
>> ip address 40.40.40.3 255.255.255.0
>> ip pim sparse-mode
>> encapsulation ppp
>> ip ospf database-filter all out
>> serial restart-delay 0
>>
>> Once we filter-lsa advertisement on A, the B router is no longer have
>> any OSPF LSA including the default Summary.
>>
>> B#sh ip os database
>>
>> OSPF Router with ID (2.2.2.2) (Process ID 10)
>>
>> Router Link States (Area 45)
>>
>> Link ID ADV Router Age Seq# Checksum Link
>> count
>> 2.2.2.2 2.2.2.2 3 0x80000001 0x007291 2
>> B#
>> B#
>> B#sh ip os database
>>
>> OSPF Router with ID (2.2.2.2) (Process ID 10)
>>
>> Router Link States (Area 45)
>>
>> Link ID ADV Router Age Seq# Checksum Link
>> count
>> 2.2.2.2 2.2.2.2 6 0x80000001 0x007291 2
>> B#sh ip route ospf
>>
>>
>> Imran
>>
>>
>>
>> -----Original Message-----
>> From: Paul Cosgrove [mailto:paul.cosgrove@heanet.ie]
>> Sent: Thursday, April 10, 2008 3:14 AM
>> To: nagendra kumar
>> Cc: Mohmmad, Imran; atif raees; ccielab@groupstudy.com
>> Subject: Re: OSPF Inra Area route filtering
>>
>> The command filters learned LSAs from being relayed on, so you should
>> still be able to send a default from the hub.
>>
>> Paul.
>>
>> nagendra kumar wrote:
>>
>>> Hi,
>>>
>>> I guess this command will filter all LSAs and so itz our
>>>
>> responsibility to configure a default route in all spoke routers.
>>
>>>
>>> Regards,
>>> Nagendra
>>>
>>> Paul Cosgrove <paul.cosgrove@heanet.ie> wrote: neighbor x.x.x.x
>>>
>> database-filter all out
>>
>>> Paul.
>>>
>>> Mohmmad, Imran wrote:
>>>
>>>> Hi there,
>>>>
>>>> What you want to filter, route entering into the routing table from
>>>>
>> OSPF
>>
>>>> LSDB or the inter-area LSA itself?
>>>>
>>>> If you want to filter the route entering from OSPF LSDB to routing
>>>>
>> table
>>
>>>> you can use the distribute-list in on OSPF process,
>>>>
>>>> If you want to filter the Intra-Area LSA itself, then with in an
>>>>
> area
>
>> it
>>
>>>> is not possible.
>>>>
>>>> Imran
>>>>
>>>> -----Original Message-----
>>>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
>>>>
>> Of
>>
>>>> atif raees
>>>> Sent: Wednesday, April 09, 2008 1:15 AM
>>>> To: ccielab@groupstudy.com
>>>> Subject: OSPF Inra Area route filtering
>>>>
>>>> Dear all
>>>>
>>>> i am experimenting a hub & spoke topology using FR.
>>>>
>>>> Each spoke has it on LAN
>>>>
>>>> Hub has area 0 & area 1 as totally stub are all FR spoke are in Area
>>>>
>> 1
>>
>>>> what i want to achieve is to filter (intra area ospf routes sent by
>>>>
>> each
>>
>>>> spoke) at hub site so that spoke can has just default route in it
>>>> routing
>>>> table which they already have as i have configured area 1 as totally
>>>> stub.
>>>>
>>>> is it possible.
>>>>
>>>> Atif Raees
>>>>
>>>>
>>>>
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