From: Paul Cosgrove (paul.cosgrove@heanet.ie)
Date: Sat Apr 12 2008 - 08:45:06 ART
Just had another look at your tests, and since B does not even have a
router LSA for A, it would not use any other LSA from A even if it
received one. The type would not matter and so the statement in the
book must be an error.
Paul.
Paul Cosgrove wrote:
> Sorry, the correct name for the book I mentioned is "Opimal Routing
> Design".
>
> Paul Cosgrove wrote:
>> 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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