From: Peter van Oene (pvo@usermail.com)
Date: Sun Oct 20 2002 - 20:57:10 GMT-3
At 05:56 PM 10/20/2002 -0400, Peter van Oene wrote:
>At 10:27 AM 10/20/2002 -0500, Brian McGahan wrote:
>>Robert,
>>
>> The command "ip ospf database-filter all out" works like passive
>>interface does in distance vector protocols. When you say 'passive
>>interface' in OSPF, you deny sending any hello packets out an interface,
>>therefore an adjacency cannot be established. With 'ip ospf
>>database-filter' on the other hand, you are only filtering the LSA
>>generation. This means that you can still establish adjacencies (since
>>hellos are still sent), but you won't send your neighboring router any
>>LSA's. Therefore you will receive all the LSA's in their database, but
>>they will not receive any of yours. Observe the following:
>
>Good points, but unless LSAs are otherwise properly such that the given
>router is able to properly represent itself, you will break
^ flooded :)
>your ospf. This is a pretty dangerous command as I think i mentioned :)
>
>
>
>
>>R1--12.0.0.0/8--R2
>>
>> R1 and R2 share an Ethernet segment running OSPF. They each
>>advertise a prefix into the OSPF domain, 1.1.1.1/32 and 2.2.2.2/32
>>respectively. R2 uses the command 'ip ospf database-filter all out' on
>>the Ethernet segment between them. Therefore, R1 does not receive the
>>LSA 2.2.2.2/32 in its OSPF database (and therefore the IP routing
>>table), yet R2 still does receive the LSA 1.1.1.1/32 and installs it in
>>the IP routing table.
>>
>>
>>R1#sh ip int brief
>>Interface IP-Address OK? Method Status
>>Protocol
>>FastEthernet0/0 12.0.0.1 YES manual up up
>>
>>Loopback0 1.1.1.1 YES manual up up
>>!
>>R1#sh run | b router ospf
>>router ospf 1
>> network 0.0.0.0 255.255.255.255 area 0
>>!
>>R1#sh ip ospf nei
>>Neighbor ID Pri State Dead Time Address
>>Interface
>>2.2.2.2 1 FULL/DR 00:00:35 12.0.0.2
>>FastEthernet0/0
>>!
>>
>>R2#sh ip int brief
>>Interface IP-Address OK? Method Status
>>Protocol
>>Ethernet0 12.0.0.2 YES manual up up
>>
>>Loopback0 2.2.2.2 YES manual up up
>>
>>!
>>R2#sh run int e0
>>interface Ethernet0
>> ip address 12.0.0.2 255.0.0.0
>> ip ospf database-filter all out
>>end
>>!
>>R2#sh run | b router ospf
>>router ospf 1
>> network 0.0.0.0 255.255.255.255 area 0
>>!
>>R2#sh ip ospf nei
>>Neighbor ID Pri State Dead Time Address
>>Interface
>>1.1.1.1 1 FULL/BDR 00:00:37 12.0.0.1
>>Ethernet0
>>!
>>
>>R2#sh ip route
>><snip>
>> 1.0.0.0/32 is subnetted, 1 subnets
>>O 1.1.1.1 [110/11] via 12.0.0.1, 00:05:43, Ethernet0
>> 2.0.0.0/32 is subnetted, 1 subnets
>>C 2.2.2.2 is directly connected, Loopback0
>>C 12.0.0.0/8 is directly connected, Ethernet0
>>!
>>R1#sh ip route
>><snip>
>> 1.0.0.0/32 is subnetted, 1 subnets
>>C 1.1.1.1 is directly connected, Loopback0
>>C 12.0.0.0/8 is directly connected, FastEthernet0/0
>>R1#
>>!
>>R1#sh ip ospf dat
>>
>> OSPF Router with ID (1.1.1.1) (Process ID 1)
>>
>> Router Link States (Area 0)
>>
>>Link ID ADV Router Age Seq# Checksum Link
>>count
>>1.1.1.1 1.1.1.1 475 0x80000005 0x7B7B 2
>>!
>>R2#sh ip ospf dat
>>
>> OSPF Router with ID (2.2.2.2) (Process ID 1)
>>
>>
>> Router Link States (Area 0)
>>
>>Link ID ADV Router Age Seq# Checksum Link
>>count
>>1.1.1.1 1.1.1.1 480 0x80000005 0x7B7B 2
>>2.2.2.2 2.2.2.2 486 0x80000006 0x27B8 2
>>
>> Net Link States (Area 0)
>>
>>Link ID ADV Router Age Seq# Checksum
>>12.0.0.2 2.2.2.2 488 0x80000001 0x29EE
>>!
>>
>>
>>
>>HTH
>>
>>Brian McGahan, CCIE #8593
>>Director of Design and Implementation
>>brian@cyscoexpert.com
>>
>>CyscoExpert Corporation
>>Internetwork Consulting & Training
>>Voice: 847.674.3392
>>Fax: 847.674.2625
>>
>>
>> > -----Original Message-----
>> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
>>Of
>> > Peter van Oene
>> > Sent: Sunday, October 20, 2002 9:08 AM
>> > To: ccielab@groupstudy.com
>> > Subject: Re: No LSA Command
>> >
>> > At 03:10 PM 10/20/2002 +1000, Robert Massiache wrote:
>> > >I have a question for your guys.
>> > >
>> > >In what context do we use the command "ip ospf database-filter all
>>out"
>> > >This very same command is used both inside "router ospf 64" as well
>>as
>> > >"interface s0".
>> >
>> > I would only use this is situations where there were parallel links
>>and I
>> > was concerned about that added processing that sending the same
>>updates
>> > down s0 that were also going to s1 toward the same router might
>> > cause. Beyond that, it's very dangerous.
>> >
>> >
>> >
>> > >William Parkhurst seems to be of very less explanatory. Could someone
>> > pour
>> > >some lime light please....
>> > >
>> > >thanks
>> > >
>> > >
>> > >
>> > >
>> > >_________________________________________________________________
>> > >Surf the Web without missing calls! Get MSN Broadband.
>> > >http://resourcecenter.msn.com/access/plans/freeactivation.asp
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