Re: OSPF conditional default route injection

I should add the following:

On R2
R2(config)#ip route 0.0.0.0 0.0.0.0 null0 track3

On Wed, Jun 9, 2010 at 9:33 AM, <ccie_at_halawlaw.com> wrote:

> Where did you apply the track??
>
> On Wed, 9 Jun 2010 09:18:19 -0700, Narbik Kocharians <narbikk_at_gmail.com>
> wrote:
> > *Here you go my friend:*
> > **
> > *Let s say you have the following topology:*
> >
> >
> >
> > *R1 (F0/0)---------- (F0/0) R2 (F0/1)-------------(F0/1) R3*
> >
> > * *
> >
> > *IP addressing:*
> >
> > *R1 s F0/0 = 10.1.12.1 /24*
> >
> > *R2 s F0/0 = 10.1.12.2 /24*
> >
> > *R2 s F0/1 = 10.1.23.2 /24*
> >
> > *R3 s F0/1 = 10.1.23.3 /24*
> >
> > *R3 s Loopback0 = 3.3.3.3 /24*
> >
> > * *
> >
> > *Routing protocols:*
> >
> > *R1 and R2 are running OSPF in area 0*
> >
> > * *
> >
> > *R2 and R3 are running Eigrp As 100, R3 s Loopback0 interface is
> advertised
> > in this routing protocol.*
> >
> >
> >
> > *Policy:*
> >
> > *R2 should inject a default route ONLY if it does NOT see network
> 3.3.3.0
> > /24 in its routing table:*
> >
> >
> >
> > *On R2*
> >
> >
> >
> > *router ospf 1*
> >
> > *network 10.1.12.2 0.0.0.0 area 0*
> >
> > *default-information originate*
> >
> >
> >
> > *We know that default-information originate on its own will NOT inject a
> > default route, and we need a default route in order to originate one.
> Let s
> > configure one:*
> >
> >
> >
> > R2(config)#*ip route 0.0.0.0 0.0.0.0 Null0*
> >
> >
> >
> > *We should see a default route injected in R1 s routing table:*
> >
> >
> >
> > *R1#Show ip route ospf | Inc O*
> >
> > * *
> >
> > *O*E2 0.0.0.0/0 [110/1] via 10.1.12.2, **00:08:09**, FastEthernet0/0*
> >
> >
> >
> > *Now let s implement the policy:*
> >
> >
> >
> > *The state of the following Boolean will ONLY be UP, if object 1 is NOT
> up
> > (Specified by the NOT keyword in the second line of the following
> > configuration):*
> >
> >
> >
> > R2(config)#*track 3 list boolean and*
> >
> > R2(config -track)#*object 1 NOT*
> >
> >
> >
> > *But the question is, what is object 1? So let s define object 1:*
> >
> >
> >
> > R2(config)#*track 1 ip route 3.3.3.0 255.255.255.0 reachability*
> >
> >
> >
> > *Now let s test:*
> >
> >
> >
> > *On R1*
> >
> >
> >
> > R1#Show ip route ospf | Inc O
> >
> > R1#
> >
> >
> >
> > *Note R1 does NOT have a default route anymore because R2 can see
> network
> > 3.3.3.0 /24 in its routing table, here is the proof:*
> >
> >
> >
> > *On R2*
> >
> >
> >
> > *R2#Show ip route | B Gate*
> >
> > Gateway of last resort is not set
> >
> >
> >
> > 3.0.0.0/24 is subnetted, 1 subnets
> >
> > *D 3.3.3.0 [90/156160] via 10.1.23.3, **00:01:56**,
> FastEthernet0/1*
> >
> > 10.0.0.0/24 is subnetted, 2 subnets
> >
> > C 10.1.12.0 is directly connected, FastEthernet0/0
> >
> > C 10.1.23.0 is directly connected, FastEthernet0/1
> >
> >
> >
> > *So let s shutdown the loopback0 interface on R3 and see the result:*
> >
> >
> >
> > *On R3*
> >
> >
> >
> > R3(config)#*Int lo0*
> >
> > R3(config-if)#*Shut*
> >
> >
> >
> > *Let s check the routing table on R1:*
> >
> >
> >
> > *On R1*
> >
> >
> >
> > *BB1#Show ip route ospf*
> >
> > * *
> >
> > *O*E2 0.0.0.0/0 [110/1] via 10.1.12.2, **00:01:07**, FastEthernet0/0*
> >
> >
> > On Wed, Jun 9, 2010 at 8:03 AM, Sorin Platon <sorin.platon_at_gmail.com>
> > wrote:
> >
> >> So i tried tested and labed the OSPF conditional default route
> injection,
> >> all the scenarios i did were to inject a default route based on the
> >> presence
> >> of a subnet in the routing table
> >>
> >> This was done trough route-maps or reliable static routes
> >>
> >> I'm trying to do the reverse, inject a default route in case a subnet
> is
> >> NOT
> >> present in the routing table
> >>
> >> I did tried the obvious and did a deny on the ACL or a deny in the
> >> routing
> >> map but didn't got the desired result
> >>
> >> is it feasible ?
> >>
> >> regards
> >> Sorin
> >>
> >>
> >> 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!
> > Training And Remote Racks available
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
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>

-- 
Narbik Kocharians
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
www.MicronicsTraining.com
Sr. Technical Instructor
YES! We take Cisco Learning Credits!
Training And Remote Racks available
Blogs and organic groups at http://www.ccie.net