Re: preferring OSPF inter-area compared to intra-area

Let me enlighten you. Read ccie99999's post, his last one.

Who ever is reading this post, please let me know if I was out of hand and
i was spamming. Don't unicast, send it to all. so you can enlighten this
gentleman.

On Mon, Jan 7, 2013 at 11:02 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:

> The subject title is preferring OSPF inter-area compared to intra-area.
> Please enlighten us as to how your input tells us how to prefer OSPF
> Inter-Area routes over Intra-Area routes.****
>
> ** **
>
> Brian McGahan, CCIE #8593 (R&S/SP/Security)****
>
> bmcgahan_at_INE.com****
>
> ** **
>
> Internetwork Expert, Inc.****
>
> http://www.INE.com****
>
> ** **
>
> *From:* Narbik Kocharians [mailto:narbikk_at_gmail.com]
> *Sent:* Tuesday, January 08, 2013 12:41 AM
> *To:* Brian McGahan
> *Cc:* ccie99999; Carlos G Mendioroz; Cisco certification
>
> *Subject:* Re: preferring OSPF inter-area compared to intra-area****
>
> ** **
>
> WOW....****
>
> First of all what I wrote is very applicable to the question that
> ccie99999 had in this post. Because he was complaining that it does not
> work. The following is his post:****
>
> "*What I was complaining is that route-map matching ip next-hop or
> matching**
> ip route-source is not working when applied with a distribute list inbound
> to ospf.
> Strange I don't find any official reference on this scenario.*"
> Did i miss something?****
>
> ** **
>
> What are you referring to? Please be more specific. ****
>
> These are NOT labs from my book, people that have my books will tell you
> that these labs are NOT from my book. I just took my time to respond with
> the configuration that clearly shows that the options work correctly.
> Besides even if I post something from my book, so what? Are you the
> moderator? Why don't we get Paul B involved, because you are totally our of
> hand. ****
>
> ** **
>
> BTW, you agreed that these options do not work, or they are not supported,
> and the above configuration proves that you are wrong. AGAIN.****
>
> ** **
>
> ** **
>
> On Mon, Jan 7, 2013 at 10:30 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:**
> **
>
> Hi Narbik,****
>
> ****
>
> I would argue that your response is spam, and is not
> applicable to the list. Once again you are posting out of context free
> lab material without answering the original posters question. I could
> likewise post output from INEs lab workbooks or from Ciscos documentation
> but that is not productive. If you have technology discussion input to
> give we are more than happy to accept it.****
>
> ****
>
> Thanks,****
>
> ****
>
> Brian McGahan, CCIE #8593 (R&S/SP/Security)****
>
> bmcgahan_at_INE.com****
>
> ****
>
> Internetwork Expert, Inc.****
>
> http://www.INE.com****
>
> ****
>
> *From:* Narbik Kocharians [mailto:narbikk_at_gmail.com]
> *Sent:* Monday, January 07, 2013 11:15 PM
> *To:* ccie99999
> *Cc:* Brian McGahan; Carlos G Mendioroz; Cisco certification****
>
>
> *Subject:* Re: preferring OSPF inter-area compared to intra-area****
>
> ****
>
> *SORRY FOR THE LONG POST.*****
>
> ****
>
> *Lets say we have a hub and spoke topology, where R1 is the hub router,
> and R2, R3, and R4 are the spoke routers. All the links are configured as
> P2P using the following IP addressing scheme:*****
>
> ****
>
> R1(S0/0.12)12.1.1.1/24--------------12.1.1.2(S0/0.21)R2****
>
> R1(S0/0.13)13.1.1.1/24--------------13.1.1.3(S0/0.31)R3****
>
> R1(S0/0.14)14.1.1.1/24--------------14.1.1.4(S0/0.41)R4****
>
> ****
>
> *R2 is running OSPF on its Lo0 and Lo1 with IP addresses of 2.2.2.2/8 and
> 200.2.2.2/24 respectively.*****
>
> * *****
>
> *R3 is running ospf on its Lo0 with an IP address of 3.3.3.3/8*****
>
> *R4 is running ospf on its Lo0 with an IP address of 4.4.4.4/8*****
>
> * *****
>
> *Everything is running in OSPF area 0. Lets begin:*****
>
> ****
>
> *On R1*****
>
> ****
>
> R1#Show ip route ospf | I O****
>
> *O 2.0.0.0/8 [110/65] via 12.1.1.2, 00:01:24, Serial0/0.12*****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:44, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:14, Serial0/0.14****
>
> *O 200.2.2.0/24 [110/65] via 12.1.1.2, 00:01:24, Serial0/0.12*****
>
> ****
>
> *You can see that R1 is receiving two routes from R2, networks 2.0.0.0/8and
> 200.2.2.0/24.*****
>
> ****
>
> *Lets filter all routes coming through S0/0.12:*****
>
> ****
>
> *On R1*****
>
> ****
>
> R1(config)#*Route-map tst deny 10*****
>
> R1(config-route-map)#*match interface s0/0.12*****
>
> R1(config)#*route-map tst permit 90*****
>
> ****
>
> R1(config-route-map)#*router ospf 1*****
>
> R1(config-router)#*distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:38, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:38, Serial0/0.14****
>
> ****
>
> *Lets remove the previous solution and filter network 2.0.0.0/8 coming
> through S0/0.21 sub-interface:*****
>
> ****
>
> R1(config)#*No route-map tst*****
>
> ****
>
> R1(config)#*router ospf 1*****
>
> R1(config-router)#*No distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 2.0.0.0/8 [110/65] via 12.1.1.2, 00:00:19, Serial0/0.12****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:19, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:19, Serial0/0.14****
>
> O 200.2.2.0/24 [110/65] via 12.1.1.2, 00:00:19, Serial0/0.12****
>
> ****
>
> *The previous solution will NOT work here; to filter network 2.0.0.0/8coming
through S0/0.21 we need to do the following:
> *****
>
> ****
>
> R1(config)#*access-list 2 permit 2.0.0.0 0.255.255.255*****
>
> ****
>
> R1(config)#*route-map tst deny 10*****
>
> R1(config-route-map)#*match interface s0/0.12*****
>
> R1(config-route-map)#*match ip addr 2*****
>
> R1(config)#*route-map tst permit 90*****
>
> ****
>
> R1(config-route-map)#*router ospf 1*****
>
> R1(config-router)#*distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:23, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:23, Serial0/0.14****
>
> O 200.2.2.0/24 [110/65] via 12.1.1.2, 00:00:23, Serial0/0.12****
>
> ****
>
> *Perfect it worked, obviously the same task can be configured using
> another method.*****
>
> * *****
>
> *Lets remove the configuration from the previous solution and filter
> network 200.2.2.0/24 coming from R2, but this time we are going to use
> the IP Next-hop option:*****
>
> ****
>
> R1(config)#*No route-map tst*****
>
> R1(config)#*No access-list 2*****
>
> ****
>
> R1(config)#*router ospf 1*****
>
> R1(config-router)#*No distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 2.0.0.0/8 [110/65] via 12.1.1.2, 00:00:29, Serial0/0.12****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:29, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:29, Serial0/0.14****
>
> O 200.2.2.0/24 [110/65] via 12.1.1.2, 00:00:29, Serial0/0.12****
>
> ****
>
> *To filter using the IP next-hop option:*****
>
> ****
>
> ****
>
> R1(config)#*access-list 1 permit 200.2.2.0 0.0.0.255*****
>
> ****
>
> R1(config)#*access-list 10 permit host 12.1.1.2*****
>
> ****
>
> R1(config)#*route-map tst deny 10*****
>
> R1(config-route-map)#*match ip addr 1*****
>
> R1(config-route-map)#*match ip next-hop 10*****
>
> R1(config)#*route-map tst permit 90*****
>
> ****
>
> R1(config-route-map)#*router ospf 1*****
>
> R1(config-router)#*distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 2.0.0.0/8 [110/65] via 12.1.1.2, 00:00:05, Serial0/0.12****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:05, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:05, Serial0/0.14****
>
> * *****
>
> *Now.lets remove the previous solution and use the route-source
> option:*****
>
> ****
>
> R1(config)#*No access-list 1* ****
>
> R1(config)#*No access-list 10* ****
>
> R1(config)#*No route-map tst*****
>
> R1(config)#*router ospf 1*****
>
> R1(config-router)#*No distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 2.0.0.0/8 [110/65] via 12.1.1.2, 00:00:34, Serial0/0.12****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:34, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:34, Serial0/0.14****
>
> O 200.2.2.0/24 [110/65] via 12.1.1.2, 00:00:34, Serial0/0.12****
>
> ****
>
> * *****
>
> *To use the route-source option, we MUST use the RID of R2 in the
> access-list. To find out the RID of R2:*****
>
> ****
>
> R2#*Show ip ospf | I ID*****
>
> *Routing Process "ospf 1" with ID 0.0.0.2*****
>
> ****
>
> R1(config)#*access-list 3 permit 0.0.0.2*****
>
> R1(config)#*access-list 30 permit 200.2.2.0 0.0.0.255*****
>
> ****
>
> R1(config)#*route-map tst deny 10*****
>
> R1(config-route-map)#*match ip addr 30*****
>
> R1(config-route-map)#*match ip route-source 3*****
>
> R1(config)#*route-map tst permit 90*****
>
> R1(config-route-map)#*router ospf 1*****
>
> R1(config-router)#*distribute-list route-map tst in*****
>
> ****
>
> R1#*Show ip route ospf | I O*****
>
> O 2.0.0.0/8 [110/65] via 12.1.1.2, 00:00:06, Serial0/0.12****
>
> O 3.0.0.0/8 [110/65] via 13.1.1.3, 00:00:06, Serial0/0.13****
>
> O 4.0.0.0/8 [110/65] via 14.1.1.4, 00:00:06, Serial0/0.14****
>
> ****
>
> ****
>
> I hope this helped. ****
>
> ****
>
> On Mon, Jan 7, 2013 at 7:09 PM, ccie99999 <ccie99999_at_gmail.com> wrote:****
>
> Thanks for your reply Brian..
>
> I see your point about filtering the RIB and not what OSPF chooses. ( I
> didn't realize this before actually)
>
> What I was complaining is that route-map matching ip next-hop or matching
> ip route-source is not working when applied with a distribute list inbound
> to ospf.
> Strange I don't find any official reference on this scenario.****
>
>
>
> On Mon, Jan 7, 2013 at 6:08 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
>
> > This filters the RIB (routing table), not the OSPF decision process. By
> > the time you apply this OSPF has already chosen the intra area route over
> > the inter area one, so all you can do is permit or deny the intra area
> one.
> >
> > The only way to really accomplish this is to make the two route types
> > equal. If you were to change the inter area route to intra area with
> > something like a virtual link or tunnel then you can modify which path is
> > preferred.
> >
>
> ****
>
> --
> @ccie99999****
>
>
>
> Blogs and organic groups at http://www.ccie.net
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>
>
>
>
> ****
>
>
>
> ****
>
> ****
>
> -- ****
>
> *Narbik Kocharians**
> *CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> *www.MicronicsTraining.com* <http://www.micronicstraining.com/>
> Sr. Technical Instructor ****
>
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner****
>
>
>
> ****
>
> ** **
>
> -- ****
>
> *Narbik Kocharians**
> *CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> *www.MicronicsTraining.com* <http://www.micronicstraining.com/>
> Sr. Technical Instructor ****
>
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner****
>

--
*Narbik Kocharians
*CCSI#30832, CCIE# 12410 (R&S, SP, Security)
*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