RE: OSPF LSA type 3 filtering

Do you mean summarizing topology information or reachability information?
Topology information is already automatically summarized at the ABR, and Type
2 LSA doesn't contain any reachability information, so I'm not sure what
you're referring to.

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>

Internetwork Expert, Inc.
http://www.INE.com

From: Narbik Kocharians [mailto:narbikk_at_gmail.com]
Sent: Wednesday, January 02, 2013 8:51 PM
To: Brian McGahan
Cc: Cisco certification
Subject: Re: OSPF LSA type 3 filtering

What if in area 1 there are some LSA type-1 and type-2? Can you not filter
them or summarize them with the "area range" command?
On Wed, Jan 2, 2013 at 6:17 PM, Brian McGahan
<bmcgahan_at_ine.com<mailto:bmcgahan_at_ine.com>> wrote:
How does it affect Type 2 LSAs?

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>

Internetwork Expert, Inc.
http://www.INE.com

-----Original Message-----
From: nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>
[mailto:nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>] On Behalf Of
Narbik Kocharians
Sent: Wednesday, January 02, 2013 4:52 PM
To: Tim Cribbs Jr.
Cc: Sarad; Cisco certification
Subject: Re: OSPF LSA type 3 filtering

Thanks very much, I am glad it helped. And yes it also handles LSA type-2.

On Wed, Jan 2, 2013 at 2:28 PM, Tim Cribbs Jr.
<tmcribbs_at_gmail.com<mailto:tmcribbs_at_gmail.com>> wrote:

> I was JUST at this exact point in my studies and was about to comment,
> but THANKFULLY Narbik got to it before me. lol
>
> BTW, area range will also work with type 2 (1&2).
>
> Tim
>
> On Wed, Jan 2, 2013 at 5:05 PM, Sarad
<tosara_at_gmail.com<mailto:tosara_at_gmail.com>> wrote:
> > Hi Narbik,
> >
> > Thanks for the in detailed expert level explanation. People like you
> > keep this forum alive. I just did a lab on this and now it make more
> > sense. So take out from this would be both these commands do the LSA
> > filtering on
> ABR
> > but Area range command would work only when filtering LSA type 1
> > regenerating as type 3.
> >
> >
> > Area-range
> >
> > LSA1 ---> LSA3
> >
> > Filter-list
> >
> > LSA1/LSA3 -----> LSA
> >
> >
> > Thanks again for the awesome explanation.
> >
> > Cheers
> > Sara
> >
> >
> > On Thu, Jan 3, 2013 at 7:49 AM, Narbik Kocharians
> > <narbikk_at_gmail.com<mailto:narbikk_at_gmail.com>>
> wrote:
> >
> >> *Sarad,*
> >> *Since we are all engineers, and engineers are "Must See" people,
> >> walk through the following lab.*
> >> **
> >> *Let s assume the following topology:*
> >>
> >>
> >>
> >> Lo0(1.1.1.1/24)-----<http://1.1.1.1/24)----->
*R1*(F0/0)12.1.1.1/24<http://12.1.1.1/24> --------
> 12.1.1.2/24(F0/0)*R2*<http://12.1.1.2/24(F0/0)*R2*>
> >>
> >>
> >>
> >> *R2*(S0/0.23)
23.1.1.2/24----------23.1.1.3/24(S0/0.32)<http://23.1.1.2/24----------23.1.1.
3/24(S0/0.32)> *R3*
> >>
> >>
> >>
> >>
*R3*(F0/0)34.1.1.3/24--------34.1.1.4/24(F0/0)*R4*<http://34.1.1.3/24--------
34.1.1.4/24(F0/0)*R4*>
> >>
> >>
> >>
> >> *OSPF Areas configuration:*
> >>
> >> R1 s Lo0 is advertised with a mask of 24 in area 1
> >>
> >> The link connecting R1 to R2 is in area 1
> >>
> >> The link connecting R2 to R3 is in area 0
> >>
> >> The link connecting R3 to R4 is in area 2
> >>
> >>
> >>
> >> *To verify:*
> >>
> >> R1#*Show ip route ospf | I O*
> >>
> >> O IA 34.1.1.0 [110/66] via 12.1.1.2, 00:04:13, FastEthernet0/0
> >>
> >> O IA 23.1.1.0 [110/65] via 12.1.1.2, 00:04:13, FastEthernet0/0
> >>
> >>
> >>
> >> R2#*Show ip route ospf | I O*
> >>
> >> O IA 34.1.1.0 [110/65] via 23.1.1.3, 00:05:05, Serial0/0.23
> >>
> >> O 1.1.1.0 [110/2] via 12.1.1.1, 00:04:35, FastEthernet0/0
> >>
> >>
> >>
> >> R3#*Show ip route ospf | I O*
> >>
> >> O IA 1.1.1.0 [110/66] via 23.1.1.2, 00:04:30, Serial0/0.32
> >>
> >> O IA 12.1.1.0 [110/65] via 23.1.1.2, 00:05:05, Serial0/0.32
> >>
> >>
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> O IA 1.1.1.0 [110/67] via 34.1.1.3, 00:04:30, FastEthernet0/0
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:04:30, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:04:30, FastEthernet0/0
> >>
> >>
> >>
> >> *Let s test the "area range" command on R3:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3(config)#*router ospf 1*
> >>
> >> R3(config-router)#*area 1 range 1.1.1.0 255.255.255.0 not-ad*
> >>
> >>
> >>
> >> *To verify the configuration:*
> >>
> >> **
> >>
> >> *On R4*
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> *O IA 1.1.1.0 [110/67] via 34.1.1.3, 00:07:07, FastEthernet0/0*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:07:07, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:07:07, FastEthernet0/0
> >>
> >>
> >> *NOTE: It did not work, because the Area range command does not
> >> work on inter-area routes at all; now let s try this command on
> >> R2:*
> >> **
> >>
> >> *On R2*
> >>
> >> R2(config)#*router ospf 1*
> >>
> >> R2(config-router)#*area 1 range 1.1.1.0 255.255.255.0 not-ad*
> >>
> >>
> >>
> >> *To verify the configuration:*
> >> **
> >> *On** R2*
> >>
> >> *NOTE: It s in the routing table and the database of the local
> >> router
> >> (R2):*
> >>
> >>
> >>
> >> R2#*sh ip route ospf | I O*
> >>
> >> O IA 34.1.1.0 [110/65] via 23.1.1.3, 00:00:33, Serial0/0.23
> >>
> >> *O 1.1.1.0 [110/2] via 12.1.1.1, 00:00:33, FastEthernet0/0*
> >>
> >>
> >>
> >> R2#*Show ip ospf da router*
> >>
> >>
> >>
> >> *Link connected to: a Stub Network*
> >>
> >> * (Link ID) Network/subnet number: 1.1.1.0*
> >>
> >> * (Link Data) Network Mask: 255.255.255.0*
> >>
> >> * Number of TOS metrics: 0*
> >>
> >> * TOS 0 Metrics: 1*
> >>
> >> * *
> >>
> >> *But is it going to be advertised to the other areas? Let s check:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3#*Show ip route ospf | I O*
> >>
> >> O IA 12.1.1.0 [110/65] via 23.1.1.2, 00:07:49, Serial0/0.32
> >>
> >>
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:18:52, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:09:14, FastEthernet0/0
> >>
> >>
> >>
> >> *As you can see the answer is "NO". *
> >>
> >> *So you can see that it prevented the LSA type-3 generation for the
> >> 1.1.1.0/24<http://1.1.1.0/24> prefix on the router that sees the route as
LSA-1 and
> LSA-3. *
> >>
> >> * *
> >>
> >> *NOW .let s test the area filter-list , but before we test it, we
> should
> >> remove the Area range command:*
> >>
> >> **
> >>
> >> *On R2*
> >>
> >> R2(config)#*router ospf 1*
> >>
> >> R2(config-router)#*No area 1 range 1.1.1.0 255.255.255.0
> >> not-advertise*
> >>
> >>
> >>
> >> *To verify the configuration:*
> >>
> >> **
> >>
> >> *On R3*
> >>
> >>
> >>
> >> R3#*Show ip route ospf | I O*
> >>
> >> *O IA 1.1.1.0 [110/66] via 23.1.1.2, 00:00:16, Serial0/0.32*
> >>
> >> O IA 12.1.1.0 [110/65] via 23.1.1.2, 00:12:47, Serial0/0.32
> >>
> >>
> >>
> >> *Let s configure the area filter-list on R2:*
> >>
> >> * *
> >>
> >> *On R2*
> >>
> >> R2(config)#*IP prefix-list tst deny 1.1.1.0/24*<http://1.1.1.0/24*>
> >>
> >> R2(config)#*IP prefix-list tst permit 0.0.0.0/0<http://0.0.0.0/0> le 32*
> >>
> >>
> >>
> >> R2(config)#*router ospf 1*
> >>
> >> R2(config-router)#*area 1 filter-list prefix tst out*
> >>
> >>
> >>
> >> *To verify the configuration:*
> >>
> >> **
> >>
> >> *On R2*
> >>
> >>
> >>
> >> R2#*Show ip route ospf | I O*
> >>
> >> O IA 34.1.1.0 [110/65] via 23.1.1.3, 00:02:12, Serial0/0.23
> >>
> >> *O 1.1.1.0 [110/2] via 12.1.1.1, 00:02:12, FastEthernet0/0*
> >>
> >>
> >>
> >> R2#*Show ip ospf da router*
> >>
> >>
> >>
> >> *Link connected to: a Stub Network*
> >>
> >> * (Link ID) Network/subnet number: 1.1.1.0*
> >>
> >> * (Link Data) Network Mask: 255.255.255.0*
> >>
> >> * Number of TOS metrics: 0*
> >>
> >> * TOS 0 Metrics: 1*
> >>
> >>
> >>
> >> *The output of the above show command reveals that the area
> >> filter-list did not do anything to the routing table or the
> >> database of the router
> that
> >> it s configured on. But let s see how it affected the other
> >> routers:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3#*Show ip route ospf | I O*
> >>
> >> O IA 12.1.1.0 [110/65] via 23.1.1.2, 00:15:36, Serial0/0.32
> >>
> >>
> >>
> >> *GR8, it worked.*
> >>
> >> *So this may seem like both area range and the area filter-list
> >> commands do the same thing, because of the end result, b**ut let s
> >> configure the "Area Filter-list" on R3. Remember in the earlier
> >> test the area range command did not work on R3:*
> >>
> >> * *
> >>
> >> *Let s remove the previous command before testing it on R3:*
> >>
> >>
> >>
> >> *On R2*
> >>
> >> R2(config)#*router ospf 1*
> >>
> >> R2(config-router)#*No area 1 filter-list prefix tst out*
> >>
> >>
> >>
> >> *To verify the configuration:*
> >>
> >> **
> >>
> >> *On R3*
> >>
> >> R3#*Show ip route ospf | I O*
> >>
> >> *O IA 1.1.1.0 [110/66] via 23.1.1.2, 00:00:10, Serial0/0.32*
> >>
> >> O IA 12.1.1.0 [110/65] via 23.1.1.2, 00:17:47, Serial0/0.32
> >>
> >>
> >>
> >> *NOW .let s configure the area filter-list on R3:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3(config)#*ip prefix-list tst deny 1.1.1.0/24*<http://1.1.1.0/24*>
> >>
> >> R3(config)#*ip prefix-list tst permit 0.0.0.0/0<http://0.0.0.0/0> le 32*
> >>
> >>
> >>
> >> R3(config)#*router ospf 1*
> >>
> >> R3(config-router)#*area 0 filter-list prefix tst out*
> >>
> >>
> >>
> >> *Let s verify the routing table of R4*
> >>
> >>
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:29:01, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:19:23, FastEthernet0/0
> >>
> >>
> >>
> >> *So you can see that it did affect the routers in area 2. *
> >>
> >> *So the area range command can be used on the ABR that is
> >> directly connected to the area that originated the route
> >> (intra-area routes) or another way of saying it (Does NOT generate
> >> LSA-3 for the other areas), whereas, the Area filter-list command
> >> affects LSA type-3s and can be configured on any ABR within your
> >> routing domain.*
> >>
> >>
> >>
> >> *You could also use the following command to accomplish the same
> >> result, the following two methods will work on LSA Type-3s going
> >> from area 0 to another area: *
> >>
> >> **
> >>
> >> *Let s remove the previous command and verify:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3(config)#*router ospf 1*
> >>
> >> R3(config-router)#*No area 0 filter-list prefi tst out*
> >>
> >>
> >>
> >> *On R4*
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> *O IA 1.1.1.0 [110/67] via 34.1.1.3, 00:00:27, FastEthernet0/0*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:35:22, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:25:44, FastEthernet0/0
> >>
> >>
> >>
> >> *Let s configure a static route on R3 and point it to Null0:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3(config)#*IP route 1.1.1.0 255.255.255.0 null0*
> >>
> >>
> >>
> >> *To verify the configuration:*
> >>
> >> **
> >>
> >> *On R4*
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:37:00, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:27:22, FastEthernet0/0
> >>
> >>
> >>
> >> *Or the following: Let s remove the previous command and verify:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3(config)#*no IP route 1.1.1.0 255.255.255.0 null0*
> >>
> >>
> >>
> >> *On R4*
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> *O IA 1.1.1.0 [110/67] via 34.1.1.3, 00:00:27, FastEthernet0/0*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:37:54, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:28:16, FastEthernet0/0
> >>
> >>
> >>
> >> *Contrary to popular belief, the distribute-list in command can
> >> affect the neighboring router/s:*
> >>
> >>
> >>
> >> *On R3*
> >>
> >> R3(config)#*access-list 1 deny 1.1.1.0 0.0.0.255*
> >>
> >> R3(config)#*access-list 1 permit any*
> >>
> >>
> >>
> >> R3(config)#*router ospf 1*
> >>
> >> R3(config-router)#*distribute-list 1 in*
> >>
> >>
> >>
> >> *On R4*
> >>
> >> R4#*Show ip route ospf | I O*
> >>
> >> O IA 23.1.1.0 [110/65] via 34.1.1.3, 00:38:55, FastEthernet0/0
> >>
> >> O IA 12.1.1.0 [110/66] via 34.1.1.3, 00:29:17, FastEthernet0/0
> >>
> >>
> >>
> >> *I hope this helped.*
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> On Tue, Jan 1, 2013 at 9:36 PM, Sarad
<tosara_at_gmail.com<mailto:tosara_at_gmail.com>> wrote:
> >>
> >>> Hi All,
> >>>
> >>> May be it's not clear what I have sent before let me put this
> >>> straight,
> >>>
> >>> Other than direction (In/Out) what are the limitations of area
> >>> range command over filter-list command in term of OSPF LSA type 3
filtering?
> >>>
> >>> Thanks
> >>> Saranga
> >>>
> >>>
> >>> On Wed, Jan 2, 2013 at 4:16 PM, Sarad
<tosara_at_gmail.com<mailto:tosara_at_gmail.com>> wrote:
> >>>
> >>> > Hi Experts,
> >>> >
> >>> > Can somebody help me to get my head around this, I've been
> >>> > labbing
> ospf
> >>> > type 3 filtering, Main method use for this is filter-list command.
> >>> Which we
> >>> > can use to filter route based on the direction (in /out)
> >>> >
> >>> >
> >>> >
> >>> > Then there is area range command with not-advertise switch we
> >>> > can
> use to
> >>> > do limited filtering on ABR. When I tested this it only works
> >>> > when I
> >>> filter
> >>> > LSA type 3 from non backbone area to a backbone area.
> >>> >
> >>> > Can somebody help me to explain what is the exact usage of this
> command
> >>> in
> >>> > term of filtering in OSPF. There is nothing much in the doc CD
> >>> >
> >>> > *
> >>> > *
> >>> > *area area-id filter-list prefix prefix-list-name {in | out}
> >>> > area* area-id *range* ipv6-prefix /prefix-length [*advertise* |
> >>> > * not-advertise*] [*cost* cost]
> >>> >
> >>> >
> >>> > Cheers
> >>> > Sara
> >>>
> >>>
> >>> Blogs and organic groups at http://www.ccie.net
> >>>
> >>> __________________________________________________________________
> >>> _____ Subscription information may be found at:
> >>> http://www.groupstudy.com/list/CCIELab.html
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >> --
> >> *Narbik Kocharians
> >> *CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> >> *www.MicronicsTraining.com<http://www.MicronicsTraining.com>*
<http://www.micronicstraining.com/>
> >> Sr. Technical Instructor
> >> YES! We take Cisco Learning Credits!
> >> A Cisco Learning Partner
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
> > ____________________________________________________________________
> > ___ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> >
> >
> >
> >
> >
> >
>

--
*Narbik Kocharians
*CCSI#30832, CCIE# 12410 (R&S, SP, Security)
*www.MicronicsTraining.com<http://www.MicronicsTraining.com>*
<http://www.micronicstraining.com/>
Sr. Technical Instructor
YES! We take Cisco Learning Credits!
A Cisco Learning Partner
Blogs and organic groups at http://www.ccie.net