Re: Multiple OSPF Adjacencies In Different Areas Out Single

From: Cristi Grigore (cristi.grigore@gmail.com)
Date: Wed Apr 09 2008 - 23:00:13 ART

Hi Matt,

are you sure you're not having problems with the tunnel due to recursive
routing?

I replicated the problem and, from R5, I was able to ping a loopback on R1
that was advertised through OSPF. Here are the configs (the link between R1
and R2 is a serial link and R2 and R5 are connected through FR but that
should'n matter):

R1:
!
interface Loopback1
 ip address 10.1.1.1 255.255.255.0
 ip ospf 1 area 0
!
interface Serial0/1/1
 ip address 155.1.32.3 255.255.255.0
 ip ospf 1 area 0
!
router ospf 1
 log-adjacency-changes
!

R2:
!
interface Tunnel0
 ip address 25.0.0.2 255.255.255.0
 ip ospf 1 area 0
 keepalive 1 3
 tunnel source 155.1.0.2
 tunnel destination 155.1.0.5
!
interface Serial0/0/0
 ip address 155.1.0.2 255.255.255.0
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 ip ospf 1 area 2
!
interface Serial0/0/1
 ip address 155.1.32.2 255.255.255.0
 ip ospf 1 area 0
!
router ospf 1
 log-adjacency-changes
 area 2 nssa
 distribute-list prefix TUNNEL_DEST in Tunnel0
!
ip prefix-list TUNNEL_DEST seq 5 deny 155.1.0.5/32
ip prefix-list TUNNEL_DEST seq 10 permit 0.0.0.0/0 le 32
!

R5:
!
interface Tunnel0
 ip address 25.0.0.5 255.255.255.0
 ip ospf 1 area 0
 keepalive 1 3
 tunnel source 155.1.0.5
 tunnel destination 155.1.0.2
!
interface Serial0/0/0
 ip address 155.1.0.5 255.255.255.0
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 ip ospf 1 area 2
!
router ospf 1
 log-adjacency-changes
 area 2 nssa
 distribute-list prefix TUNNEL_DEST in Tunnel0
!
ip prefix-list TUNNEL_DEST seq 5 deny 155.1.0.2/32
ip prefix-list TUNNEL_DEST seq 10 permit 0.0.0.0/0 le 32
!

Now, the ping to R1's loopback 10.1.1.1 is working:
R5#sir
[..]
     155.1.0.0/16 is variably subnetted, 3 subnets, 2 masks
O 155.1.0.2/32 [110/64] via 155.1.0.2, 00:09:56, Serial0/0/0
C 155.1.0.0/24 is directly connected, Serial0/0/0
O 155.1.32.0/24 [110/11175] via 25.0.0.2, 00:09:56, Tunnel0
     25.0.0.0/24 is subnetted, 1 subnets
C 25.0.0.0 is directly connected, Tunnel0
     10.0.0.0/32 is subnetted, 1 subnets
O 10.1.1.1 [110/11176] via 25.0.0.2, 00:09:56, Tunnel0
R5#ping 10.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 68/69/72 ms
R5#

On Thu, Apr 10, 2008 at 1:38 AM, Matt Bentley <mattdbentley@gmail.com>
wrote:

> Hi GS:
>
> I know this sounds pretty weird, but here's is what's going on.
>
>
> R1<--------------R2--------------------->R5
> (area 0) Fa0/0 (e0/0)
> <------------------------>
> NSSA Area
> GRE Tunnel
>
> I have an OSPF adjacency over both the GRE tunnel as well as over the
> physical interfaces on R2 and R5.
>
> Here is relevant config:
>
> R2:
> int tun0
> tunnel source fa0/0
> tunnel destination 141.1.0.5
> ip add 1.1.1.2 255.255.255.0
>
> router ospf 1
> network 141.1.0.2 0.0.0.0 area 2
> network 1.1.1.2 0.0.0.0 area 0
>
>
> R5:
> int tun0
> tunnel source e0/0
> tunnel destination 141.1.0.2
> ip add 1.1.1.5 255.255.255.0
>
> router ospf 1
> network 141.1.0.2 0.0.0.0 area 2
> network 1.1.1.5 0.0.0.0 area 0
>
> For some reason I don't know, the tunnel adjacency won't come up unless I
> have the tunnel sources be the directly connected interfaces. I CAN reach
> R2 from R5, but CAN'T reach R1 from R5, even though R5 has a route which
> appears to trace (based on the "show ip route" output) directly as it
> should
> go to get to R1. R1 can get to R5 (I know this because of debugging ICMP
> -which R5 receives, and subsequently sends a packet to R1, but it never
> gets
> there. As soon as I configure a static route on R5 - and it doesn't
> matter
> whether it is to the tunnel interface or to e0/0, then I can ping that
> prefix. The traffic must be getting blackholed someplace, but I really
> can't figure out where. Thanks in advance for everybody's help.
>
>
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>
>
> 

-- 
Thank you,
Cristi Grigore

Pass the CCIE in six weeks, Guaranteed!
http://www.certscience.com/CCIE

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