From: zzk (ccie_99@yahoo.com)
Date: Tue Dec 09 2003 - 23:19:19 GMT-3
Thanks to all.
Brian, there might be another solution using ABR LSA3
filtering.
Anyway, I think it is best to change the network
design instead of scraching head... :)
--- Brian McGahan <bmcgahan@internetworkexpert.com>
wrote:
> OSPF (and IGP in general) is not designed with
> complex routing
> policy in mind. Instead this is what BGP is
> designed to do. I have seen a
> few large networks that run BGP with themselves in
> order to sort out their
> routing policy. Maybe this is something you should
> consider as a long term
> solution to your problem.
>
> In the short term as previously suggested there are
> two solutions.
> You can either poison the distance of the default
> learned from the ABR or
> filter it out using a route-map distribute-list. In
> either case this would
> have to be performed on every router in the area, as
> an LSA cannot be
> removed from the database, only the route can be
> removed from the routing
> table.
>
> HTH,
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Direct: 708-362-1418 (Outside the US and Canada)
>
> > -----Original Message-----
> > From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> > zzk
> > Sent: Tuesday, December 09, 2003 4:59 AM
> > To: Brian McGahan; 'Scott Morris';
> ccielab@groupstudy.com
> > Subject: RE: how to filter out default route in
> OSPF totally stub area?
> >
> > Hello
> >
> > Thanks for the illustration, Brian.
> > Our problem is there is a ABR router R1 generating
> a
> > IA type default route into the network (because
> the
> > area is totally stub NSSA), and another ASBR R2
> > generating a external type default route.
> > All the routers chose R1 as the default gateway,
> > because LSA type 3 is prefered over LSA type 7.
> >
> > Is there anyway we can make the routers to select
> R2
> > as the default gateway?
> > There is one ABR LSA type 3 filtering feature,
> however
> > it is not avaliable on Cat6 MSFC. :(
> >
> > thanks
> >
> >
> > --- Brian McGahan
> <bmcgahan@internetworkexpert.com>
> > wrote:
> > > A not-so-totally-stubby area (nssa no-summary)
> is a
> > > totally stubby
> > > area that you can redistribute into. The ABR of
> the
> > > NSTSA automatically
> > > originates a default of LSA type-3 into the
> area:
> > >
> > > Rack1R1#sh run | b router ospf
> > > router ospf 1
> > > area 12 nssa
> > > network 12.0.0.1 0.0.0.0 area 12
> > >
> > > Rack1R2#sh run | b router ospf
> > > router ospf 1
> > > area 12 nssa no-summary
> > > network 12.0.0.2 0.0.0.0 area 12
> > > network 150.1.2.2 0.0.0.0 area 0
> > >
> > > Rack1R1#show ip route ospf
> > > O*IA 0.0.0.0/0 [110/11] via 12.0.0.2, 00:02:49,
> > > Ethernet0/0
> > > Rack1R1#show ip ospf database
> > >
> > > OSPF Router with ID (150.1.1.1)
> (Process
> > > ID 1)
> > >
> > > Router Link States (Area 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum Link count
> > > 150.1.1.1 150.1.1.1 188
> > > 0x80000002 0x0006CE 1
> > > 150.1.2.2 150.1.2.2 188
> > > 0x80000003 0x00F8D2 1
> > >
> > > Net Link States (Area 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum
> > > 12.0.0.2 150.1.2.2 189
> > > 0x80000001 0x001342
> > >
> > > Summary Net Link States (Area
> 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum
> > > 0.0.0.0 150.1.2.2 211
> > > 0x80000001 0x00CBCE
> > >
> > >
> > > An NSSA for which the ABR originates a default
> is
> > > different (nssa
> > > default-information-originate). This is an LSA
> > > type-7 default (N1 or N2, N2
> > > by default):
> > >
> > > Rack1R2#sh run | b router ospf
> > > router ospf 1
> > > log-adjacency-changes
> > > area 12 nssa default-information-originate
> > > network 12.0.0.2 0.0.0.0 area 12
> > > network 150.1.2.2 0.0.0.0 area 0
> > >
> > > Rack1R1#sh ip route ospf
> > > 150.1.0.0/16 is variably subnetted, 3
> subnets,
> > > 2 masks
> > > O IA 150.1.2.2/32 [110/11] via 12.0.0.2,
> > > 00:00:46, Ethernet0/0
> > > O*N2 0.0.0.0/0 [110/1] via 12.0.0.2, 00:00:42,
> > > Ethernet0/0
> > > Rack1R1#sh ip ospf database
> > >
> > > OSPF Router with ID (150.1.1.1)
> (Process
> > > ID 1)
> > >
> > > Router Link States (Area 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum Link count
> > > 150.1.1.1 150.1.1.1 568
> > > 0x80000002 0x0006CE 1
> > > 150.1.2.2 150.1.2.2 568
> > > 0x80000003 0x00F8D2 1
> > >
> > > Net Link States (Area 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum
> > > 12.0.0.2 150.1.2.2 569
> > > 0x80000001 0x001342
> > >
> > > Summary Net Link States (Area
> 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum
> > > 150.1.2.2 150.1.2.2 54
> > > 0x80000001 0x00EF0F
> > >
> > > Type-7 AS External Link States
> (Area
> > > 12)
> > >
> > > Link ID ADV Router Age Seq#
> > > Checksum Tag
> > > 0.0.0.0 150.1.2.2 50
> > > 0x80000001 0x0040C7 0
> > >
> > >
> > >
> > >
> > > Brian McGahan, CCIE #8593
> > > bmcgahan@internetworkexpert.com
> > >
> > > Internetwork Expert, Inc.
> > > http://www.InternetworkExpert.com
> > > Toll Free: 877-224-8987
> > > Direct: 708-362-1418 (Outside the US and Canada)
> > >
> > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com
> > > [mailto:nobody@groupstudy.com] On Behalf Of
> > > > Scott Morris
> > > > Sent: Monday, December 08, 2003 11:46 AM
> > > > To: 'zzk'; ccielab@groupstudy.com
> > > > Subject: RE: how to filter out default route
> in
>
=== message truncated ===
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This archive was generated by hypermail 2.1.4 : Sat Jan 03 2004 - 08:25:38 GMT-3