From: Robert Massiache (robert2140@hotmail.com)
Date: Sun Oct 20 2002 - 21:00:08 GMT-3
thanks a lot Brian! I appreciate your time and your help.
>From: "Brian McGahan" <brian@cyscoexpert.com>
>To: "'Robert Massiache'" <robert2140@hotmail.com>, <ccielab@groupstudy.com>
>Subject: RE: No LSA Command
>Date: Sun, 20 Oct 2002 10:27:40 -0500
>
>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:
>
>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
This archive was generated by hypermail 2.1.4 : Tue Nov 05 2002 - 08:35:52 GMT-3