Solved: One way Routing help

GanioG-42 · ‎10-25-2011

I am working on my FINAL for my CCNP class, and I have everything set up and working except one MAJOR part. I am supposed to be able to ping from the lo1 on R1 to lo1 are R6. EIGRP, BGP and Multiple OSPF areas are being used. I can ping from R6 to R1 but not the other way around. I'm "sure" its a OSPF in to BGP redistribution error in my config, but where? Every router with the exception of R1 can ping each other router. I can post configs as needed.

Obviously I'm not exactly looking for someone to do the final for me, I just need a prod in the right direction.

Vaibhava Varma · ‎10-25-2011

Hi Gregory

I was thinking on this and the very first post with diagram said Area 3 as to be NSSA Totally Stubby Area only allowing Type 7 LSA but when relooked at the R6 routing table its actually a NSSA only and hence the OE2 routes for the R1's Serial links 172.16.12.0/24 and 172.16.23.0/24 will not propogate into R6.

If we take a look at the show ip route of R6 they would still be missing.

To solve this issue please make Area 3 as NSSA Totally Stuuby by using the below command under R5 and R6 OSPF config so that R5 sends a default route to R6 and the issue will be solved.

R5 and R6

router ospf 1

area 3 nssa no-summary.

Hope this helps to solve this issue. Do let me know for any questions.

Regards

Varma

View solution in original post

GanioG-42 · ‎10-25-2011

And the Configs for R1 and R2, there might be some stuff that doesn't make sense to why I did something one way or another, I am still but a student .

version 12.4

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname R1

!

boot-start-marker

boot-end-marker

!

no aaa new-model

memory-size iomem 5

ip cef

!

multilink bundle-name authenticated

!

archive

log config

hidekeys

!

interface Loopback0

ip address 2.2.2.2 255.255.255.0

!

interface FastEthernet0/0

no ip address

shutdown

duplex auto

speed auto

!

interface Serial0/0

bandwidth 44736

ip address 172.16.12.2 255.255.255.0

clock rate 2000000

!

interface FastEthernet0/1

no ip address

shutdown

duplex auto

speed auto

!

interface Serial0/1

bandwidth 1581

ip address 172.16.12.4 255.255.255.0

clock rate 2000000

!

interface Serial0/2

ip address 172.16.23.2 255.255.255.0

clock rate 2000000

!

interface Serial0/3

no ip address

shutdown

clock rate 2000000

!

router ospf 1

log-adjacency-changes

redistribute bgp 1100 subnets

network 2.2.2.0 0.0.0.255 area 0

network 172.16.23.0 0.0.0.255 area 0

!

router bgp 1100

no synchronization

bgp log-neighbor-changes

network 172.16.23.0

redistribute ospf 1

neighbor 172.16.12.1 remote-as 7018

neighbor 172.16.12.3 remote-as 7018

no auto-summary

!

ip forward-protocol nd

!

ip http server

no ip http secure-server

!

control-plane

!

line con 0

exec-timeout 0 0

logging synchronous

line aux 0

line vty 0 4

login

!

end

Vaibhava Varma · ‎10-25-2011

Hi Gregory

One Way routing indicates source-based routing issue. What is the source and destination IP in question.

Please check that when you ping the from R1 to R6 the source IP which you are pinging with on R1 is present in the routing table of R6 and the destination IP of R6 is present in the R1 routing table.

Are you using virtual-links between R6 and R4 becuase per your diagram they seem to be in different OSPF Areas I gues OSPF1 here means OSPF Area 1 not OSPF PID 1 ?

Hope this helps you in your query.

Regards

Varma

cadet alain · ‎10-25-2011

Hi,

so on R1 ping 12.127.17.71 so lo1 is not working but on R6 ping 13.127.16.69 so lo1 is working ?

on R1 you are supposed to advertise Lo1 network via eBGP to R2 and R2 redistributes this prefix into OSPF, right?

on R6 you redistribute the Lo1 from EIGRP into the NSSA area 3 between R6-R5, right?

then on R2 you redistribute OSPF into BGP

assuming all my assumptions are correct then cna you start by doing the following show commands:

-on R1: sh ip bgp 13.127.16.69 and sh ip bgp 13.127.17.71

-on R2: sh ip bgp 13.127.16.69 and sh ip ospf database 13.127.16.69

-on R2: sh ip bgp 13.127.17.71 and sh ip ospf database 13.127.17.71

-on R3: sh ip route 13.127.16.69

Regards.

Alain.

-

Don't forget to rate helpful posts.

GanioG-42 · ‎10-25-2011

Verma, Yes I am using a virtual link to connect R6 to Area 0, and yes, they are OSPF Areas, no PIDs, sorry for the confusion.

Alain,

R1#show ip bgp 12.127.16.69

BGP routing table entry for 12.127.16.69/32, version 3

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

1

Local

0.0.0.0 from 0.0.0.0 (12.127.16.69)

Origin incomplete, metric 0, localpref 100, weight 32768, valid, sourced, best

R1#show ip bgp 12.127.17.71

% Network not in table

R1#

R2#sh ip bgp 12.127.16.69

BGP routing table entry for 12.127.16.69/32, version 11

Paths: (2 available, best #2, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

1

7018

172.16.12.3 from 172.16.12.3 (12.127.16.69)

Origin incomplete, metric 0, localpref 100, valid, external

7018

172.16.12.1 from 172.16.12.1 (12.127.16.69)

Origin incomplete, metric 0, localpref 100, valid, external, best

R2#sh ip ospf database 12.127.16.69

^

% Invalid input detected at '^' marker.

R2#sh ip bgp 12.127.17.71

% Network not in table

R3#sh ip route 12.127.17.71

Routing entry for 12.127.17.71/32

Known via "ospf 1", distance 110, metric 20, type extern 2, forward metric 128

Last update from 172.16.35.5 on Serial0/1, 00:12:32 ago

Routing Descriptor Blocks:

* 172.16.35.5, from 5.5.5.5, 00:12:32 ago, via Serial0/1

Route metric is 20, traffic share count is 1

BUT

R1#show ip route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

B 2.2.2.0 [20/0] via 172.16.12.2, 00:00:33

3.0.0.0/32 is subnetted, 1 subnets

B 3.3.3.3 [20/65] via 172.16.12.2, 00:00:33

4.0.0.0/32 is subnetted, 1 subnets

B 4.4.4.4 [20/129] via 172.16.12.2, 00:00:33

5.0.0.0/32 is subnetted, 1 subnets

B 5.5.5.5 [20/129] via 172.16.12.2, 00:00:33

172.16.0.0/24 is subnetted, 5 subnets

B 172.16.56.0 [20/192] via 172.16.12.2, 00:00:33

B 172.16.34.0 [20/128] via 172.16.12.2, 00:00:33

B 172.16.35.0 [20/128] via 172.16.12.2, 00:00:34

B 172.16.23.0 [20/0] via 172.16.12.2, 00:00:34

C 172.16.12.0 is directly connected, Serial0/0

is directly connected, Serial0/1

12.0.0.0/32 is subnetted, 2 subnets

S 12.127.17.71 [1/0] via 172.16.56.0

C 12.127.16.69 is directly connected, Loopback1

R2#sh ip route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

B 1.1.1.0 [20/0] via 172.16.12.1, 00:13:45

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/65] via 172.16.23.3, 00:15:05, Serial0/2

4.0.0.0/32 is subnetted, 1 subnets

O IA 4.4.4.4 [110/129] via 172.16.23.3, 00:15:05, Serial0/2

5.0.0.0/32 is subnetted, 1 subnets

O IA 5.5.5.5 [110/129] via 172.16.23.3, 00:14:55, Serial0/2

6.0.0.0/24 is subnetted, 1 subnets

O E2 6.6.6.0 [110/20] via 172.16.23.3, 00:14:55, Serial0/2

172.16.0.0/24 is subnetted, 5 subnets

O IA 172.16.56.0 [110/192] via 172.16.23.3, 00:14:55, Serial0/2

O IA 172.16.34.0 [110/128] via 172.16.23.3, 00:15:05, Serial0/2

O IA 172.16.35.0 [110/128] via 172.16.23.3, 00:15:05, Serial0/2

C 172.16.23.0 is directly connected, Serial0/2

C 172.16.12.0 is directly connected, Serial0/0

is directly connected, Serial0/1

12.0.0.0/32 is subnetted, 2 subnets

O E2 12.127.17.71 [110/20] via 172.16.23.3, 00:14:55, Serial0/2

B 12.127.16.69 [20/0] via 172.16.12.1, 00:13:46

R6#sh ip ro

Gateway of last resort is not set

2.0.0.0/32 is subnetted, 1 subnets

O IA 2.2.2.2 [110/193] via 172.16.56.5, 00:16:42, Serial0/0

3.0.0.0/32 is subnetted, 1 subnets

O IA 3.3.3.3 [110/129] via 172.16.56.5, 00:16:42, Serial0/0

4.0.0.0/32 is subnetted, 1 subnets

O IA 4.4.4.4 [110/193] via 172.16.56.5, 00:16:42, Serial0/0

5.0.0.0/32 is subnetted, 1 subnets

O 5.5.5.5 [110/65] via 172.16.56.5, 00:16:54, Serial0/0

6.0.0.0/24 is subnetted, 1 subnets

C 6.6.6.0 is directly connected, Loopback0

172.16.0.0/24 is subnetted, 4 subnets

C 172.16.56.0 is directly connected, Serial0/0

O IA 172.16.34.0 [110/192] via 172.16.56.5, 00:16:42, Serial0/0

O IA 172.16.35.0 [110/128] via 172.16.56.5, 00:16:55, Serial0/0

S 172.16.23.0 [1/0] via 172.16.56.0

12.0.0.0/32 is subnetted, 2 subnets

C 12.127.17.71 is directly connected, Loopback1

S 12.127.16.69 [1/0] via 172.16.56.0

So... I actually think I know where the problem is now, but how to solve it! R1 is looping to R2 and back, but why?

R6#traceroute 12.127.16.69

Type escape sequence to abort.

Tracing the route to 12.127.16.69

1 172.16.56.5 4 msec 12 msec 4 msec

2 172.16.35.3 8 msec 20 msec 4 msec

3 172.16.23.2 4 msec 32 msec 8 msec

4 172.16.12.3 8 msec 28 msec *

R6#

R1#traceroute 12.127.17.71

Type escape sequence to abort.

Tracing the route to 12.127.17.71

1 172.16.12.2 8 msec

172.16.12.4 4 msec

172.16.12.2 28 msec

2 * * *

3 * * *

4 * * *

5 * * *

6

R1#

cadet alain · ‎10-25-2011

Hi,

ip route 12.127.17.71 255.255.255.255 172.16.56.0

why did you do that? and it's incorrect because you must configure an ip address as next-hop not a subnet and this next-hop must be R2 ip address.

Regards.

Alain.

Don't forget to rate helpful posts.

Vaibhava Varma · ‎10-25-2011

Hi Gregory

Seems the issue is that the Source Subnet 172.16.12.0/24 which is sourcing the trace to R6 Lo1 12.127.17.71 is not present in the routing table of R6 and as I said before its a source based routing issue.

So to solve this issue we need to do below under OSPF config of R2..

a)under OSPF 1 redistribute connected subnet 172.16.12.0/24 and

Also on a side note

On R2 we need to include the match internal external 1 external 2 while redistributing into BGP the OSPF which will make the Lo1 of R6 ie 12.127.17.71 present in the routing table of R1 and we would not need the Static Route

The Problem here is that by default OSPF External Routes are not redistributed while redistribution.so we needed a Static Route on R1.

For sending the R6 Lo1 route directly to R1 and removing static route we need to do below under BGP config of R2

b) under BGP match external routes while OSPF to BGP redistribution

router bgp 1100

redistribute ospf 1 match internal external 1 external 2

!

Also I was wondering on R1 and R2 how did you manage to configure the same Subnet 172.16.12.0/24 on two different physical interfaces ? 172.16.12.1/24 and 172.16.12.3/24

Hope this clarifies your doubt and help solve the issue.

Regards

Varma

Hope this helps to solve your issue.

Regards

Varma

GanioG-42 · ‎10-25-2011

Ok, I had wondered about the 172.16.12.1-4, while i was drawing everying out it seemed the easy way to keep everything clear, it has been changed to 172.16.12.1-2 and 172.16.21.1-2.

As for the static routes, I had been playing around with those, at one point I thought they might be the answer, but I'm not so sure now.

Vaibhava Varma · ‎10-25-2011

Hi Gregory

Did you try configuring the above points on R2 which I have suggested above ?

On R2

router ospf 1

redistribute connected subnets

!

router bgp 1100

redistribute ospf 1 match internal external 1 external 2

!

Regards

Varma

GanioG-42 · ‎10-25-2011

Yes, I have done that, and had those statements in originally before I added static routes. Now, traceroute from R1 to R6 lo1 gets to R5's s0/1 (172.16.35.5) and then dies... Which is very confusing to me

Vaibhava Varma · ‎10-25-2011

HI Gregory

Can you please check the routing table of R5 and ensure it has both the routes for the source and destination under question ie R6 Lo1 and R1 172.16.12.0/24 and 172.16.21.0/24

Regards

Varma

GanioG-42 · ‎10-25-2011

Yeap, they are there,

R5#show ip route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

O E2 1.1.1.0 [110/1] via 172.16.35.3, 00:23:57, Serial0/1

2.0.0.0/32 is subnetted, 1 subnets

O 2.2.2.2 [110/129] via 172.16.35.3, 02:21:36, Serial0/1

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/65] via 172.16.35.3, 02:21:36, Serial0/1

4.0.0.0/32 is subnetted, 1 subnets

O IA 4.4.4.4 [110/129] via 172.16.35.3, 02:21:36, Serial0/1

5.0.0.0/24 is subnetted, 1 subnets

C 5.5.5.0 is directly connected, Loopback0

6.0.0.0/24 is subnetted, 1 subnets

O N2 6.6.6.0 [110/20] via 172.16.56.6, 02:21:51, Serial0/0

172.16.0.0/24 is subnetted, 6 subnets

C 172.16.56.0 is directly connected, Serial0/0

O IA 172.16.34.0 [110/128] via 172.16.35.3, 02:21:37, Serial0/1

C 172.16.35.0 is directly connected, Serial0/1

O E2 172.16.21.0 [110/20] via 172.16.35.3, 01:19:23, Serial0/1

O 172.16.23.0 [110/128] via 172.16.35.3, 02:21:37, Serial0/1

O E2 172.16.12.0 [110/20] via 172.16.35.3, 01:21:55, Serial0/1

12.0.0.0/32 is subnetted, 2 subnets

O N2 12.127.17.71 [110/20] via 172.16.56.6, 02:21:52, Serial0/0

O E2 12.127.16.69 [110/1] via 172.16.35.3, 00:23:58, Serial0/1

R5#

Vaibhava Varma · ‎10-25-2011

Hi Gregory

I was thinking on this and the very first post with diagram said Area 3 as to be NSSA Totally Stubby Area only allowing Type 7 LSA but when relooked at the R6 routing table its actually a NSSA only and hence the OE2 routes for the R1's Serial links 172.16.12.0/24 and 172.16.23.0/24 will not propogate into R6.

If we take a look at the show ip route of R6 they would still be missing.

To solve this issue please make Area 3 as NSSA Totally Stuuby by using the below command under R5 and R6 OSPF config so that R5 sends a default route to R6 and the issue will be solved.

R5 and R6

router ospf 1

area 3 nssa no-summary.

Hope this helps to solve this issue. Do let me know for any questions.

Regards

Varma

GanioG-42 · ‎10-25-2011

That was it! yes! Thank you!

Gregory J Ganio

Vaibhava Varma · ‎10-25-2011

HI Gregory

Glad to hear that the issue is resolved

Regards

Varma