Re: OSPF Distance Command .!

Paul Cosgrove,

I tried your topology..
 R3
    / \
  R1 R2
   \ /
     R0

R3 does not run any routing protocols, but has Lo0: 3.3.3.3 for testing.
R1 and R2 both have static routes to R3's loopback.
R0, R1 and R2 run OSPF between each other.

this is my config
***********************
R0********************
***********************
interface Loopback0
 ip address 100.100.100.100 255.255.255.0
!
interface Serial0/0
 ip address 10.1.1.1 255.255.255.252
 serial restart-delay 0
!
interface Serial0/1
 ip address 20.1.1.1 255.255.255.252
 serial restart-delay 0
!
interface Serial0/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial0/3
 no ip address
 shutdown
 serial restart-delay 0
!
router ospf 1
 router-id 100.100.100.100
 log-adjacency-changes
 network 10.1.1.1 0.0.0.0 area 0
 network 20.1.1.1 0.0.0.0 area 0
 network 100.100.100.100 0.0.0.0 area 0
!
ip http server
ip forward-protocol nd
!

***********************
R1********************
***********************
interface Loopback0
 ip address 1.1.0.1 255.255.255.0
!
interface Serial0/0
 ip address 10.1.1.2 255.255.255.252
 serial restart-delay 0
!
interface Serial0/1
 ip address 13.1.1.1 255.255.255.252
 serial restart-delay 0
!
interface Serial0/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial0/3
 no ip address
 shutdown
 serial restart-delay 0
!
router ospf 1
 router-id 1.1.0.1
 log-adjacency-changes
 redistribute static subnets
 network 1.1.0.1 0.0.0.0 area 0
 network 10.1.1.2 0.0.0.0 area 0
!
ip http server
ip forward-protocol nd
ip route 3.3.0.3 255.255.255.255 Serial0/1 13.1.1.2
!
***********************
R2********************
***********************
interface Loopback0
 ip address 2.2.0.2 255.255.255.0
!
interface Serial0/0
 ip address 20.1.1.2 255.255.255.252
 serial restart-delay 0
!
interface Serial0/1
 ip address 23.1.1.1 255.255.255.252
 serial restart-delay 0
!
interface Serial0/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial0/3
 no ip address
 shutdown
 serial restart-delay 0
!
router ospf 1
 router-id 2.2.0.2
 log-adjacency-changes
 redistribute static subnets
 network 2.2.0.2 0.0.0.0 area 0
 network 20.1.1.2 0.0.0.0 area 0
!
ip http server
ip forward-protocol nd
ip route 3.3.0.3 255.255.255.255 Serial0/1 23.1.1.2
!
***********************
R3********************
***********************
!
interface Loopback0
 ip address 3.3.0.3 255.255.255.0
!
interface Serial0/0
 ip address 13.1.1.2 255.255.255.252
 serial restart-delay 0
!
interface Serial0/1
 ip address 23.1.1.2 255.255.255.252
 serial restart-delay 0
!
interface Serial0/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial0/3
 no ip address
 shutdown
 serial restart-delay 0
!
ip http server
ip forward-protocol nd
!
!
!

and this is my routing table at R0
R0#sir
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static
route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
O 1.1.0.1 [110/65] via 10.1.1.2, 00:00:01, Serial0/0
     2.0.0.0/32 is subnetted, 1 subnets
O 2.2.0.2 [110/65] via 20.1.1.2, 00:00:01, Serial0/1
     100.0.0.0/24 is subnetted, 1 subnets
C 100.100.100.0 is directly connected, Loopback0
     3.0.0.0/32 is subnetted, 1 subnets
O E2 3.3.0.3 [110/20] via 20.1.1.2, 00:00:01, Serial0/1
                [110/20] via 10.1.1.2, 00:00:01, Serial0/0
     20.0.0.0/30 is subnetted, 1 subnets
C 20.1.1.0 is directly connected, Serial0/1
     10.0.0.0/30 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0/0

It does Load balancing.!

R0#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
1.1.0.1 0 FULL/ - 00:00:38 10.1.1.2 Serial0/0
2.2.0.2 0 FULL/ - 00:00:34 20.1.1.2 Serial0/1

i did try shutting interafces... clear ip route * , clear ip ospf process

no change in the OUTcome.!

Thanking You

Yours Sincerely

Divin Mathew John
divinjohn_at_gmail.com
divin_at_dide3d.com
http://www.dide3d.com
+91 9945430983
+91 9846697191
+974 5008916
PGP PUBLIC KEY BLOCK @ http://www.dide3d.com/divin_Public_PGP_key.txt
Sent from Bangalore, KA, India

On Fri, May 22, 2009 at 8:59 PM, Paul Cosgrove <paul.cosgrove_at_gmail.com>wrote:

> Hi Sadiq,
>
> I would have to recommend trying it again yourself, as it does work:
>
> R1 ----- R2
> \ /
> \ /
> \ /
> R0
>
> All links are network type point to point. Shutdown interfaces, cleared
> ospf process, no shut and waited for neighbors to establish.
>
> R0 then shows the following:
>
> Gateway of last resort is not set
>
> O 192.168.12.0/24 [110/128] via 192.168.20.2, 00:00:58, Serial1/1
> [110/128] via 192.168.10.1, 00:00:58, Serial1/0
> 1.0.0.0/32 is subnetted, 1 subnets
> O 1.1.1.1 [110/65] via 192.168.10.1, 00:00:58, Serial1/0
> 2.0.0.0/32 is subnetted, 1 subnets
> O 2.2.2.2 [110/65] via 192.168.20.2, 00:00:58, Serial1/1
> C 192.168.10.0/24 is directly connected, Serial1/0
> C 192.168.20.0/24 is directly connected, Serial1/1
> 10.0.0.0/32 is subnetted, 1 subnets
> C 10.10.10.10 is directly connected, Loopback0
>
> R0(config)#access-list 10 permit 192.168.12.0
> R0(config)#router ospf 1
> R0(config-router)#distance 90 1.1.1.1 0.0.0.0 10
> R0(config-router)#do sh ip ro
> Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
> ia - IS-IS inter area, * - candidate default, U - per-user static
> route
> o - ODR, P - periodic downloaded static route
>
> Gateway of last resort is not set
>
> O 192.168.12.0/24 [90/128] via 192.168.10.1, 00:00:05, Serial1/0
> 1.0.0.0/32 is subnetted, 1 subnets
> O 1.1.1.1 [110/65] via 192.168.10.1, 00:00:05, Serial1/0
> 2.0.0.0/32 is subnetted, 1 subnets
> O 2.2.2.2 [110/65] via 192.168.20.2, 00:00:05, Serial1/1
> C 192.168.10.0/24 is directly connected, Serial1/0
> C 192.168.20.0/24 is directly connected, Serial1/1
> 10.0.0.0/32 is subnetted, 1 subnets
> C 10.10.10.10 is directly connected, Loopback0
> R0(config-router)#
>
> AD can and is often used to differentiate routes in the same protocol.
> EIGRP externals and BGP internal routes being some obvious examples.
> Paul.
>
>
>
> Sadiq Yakasai wrote:
>
>> Gents, a little search over GS archives would second Bryan's point! This
>> issue hunted me down in my first attempt!
>>
>> While some have even gone to TAC, others have tried bugging it! But from
>> the
>> research I carried out a while ago, my conclusion is you are not to use AD
>> to influence prefix selection WITHIN the same routing protocol - use
>> metric
>> instead! BETWEEN 2 or more routing protocols, use AD.
>>
>> Otherwise, you are in for a long, unreliable and incoherent exercise.
>>
>> Sadiq
>>
>> On Fri, May 22, 2009 at 3:23 PM, Bryan Bartik <bbartik_at_ipexpert.com>
>> wrote:
>>
>>
>>
>>> Hello,
>>>
>>> Divin, I think you hit it right on :) I have labbed this several times
>>> before and what I found was that you cannot use AD to prefer one ospf
>>> route
>>> over another in the same ospf process (There may be crazy scenarios where
>>> you can, but I don't recall finding any). Makes sense, since like you
>>> said
>>> AD is to prefer one protocol over another. You could place the link to R1
>>> in
>>> another process on R0 and then change the distance in that process.
>>>
>>> Bryan Bartik
>>> CCIE #23707 (R&S), CCNP
>>> Sr. Support Engineer - IPexpert, Inc.
>>> URL: http://www.IPexpert.com
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
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Received on Fri May 22 2009 - 21:13:50 ART