OSPF not forming adjacency

[gunnydaman]

Hello everyone,

I am currently working on simulated network environment in preparation for a real-time environment. Within my network environment I have two routers connected by a GRE tunnel/ipsec vpn using EIGRP as a routing protocol. I then have Nexus 9k attached to the hub router and a 3560 ios switch attached to the peer end. I am able to ping the outside interface of both switches from both switches however, when I set up OSPF for the inside routing I cannot form an adjacency.

Can someone please look at my configs and help me figure out what I need to do to get OSPF working on my L3 switches. Is it a natting problem or maybe a multi-point problem?

Any help would be appreciated.

Thanks,

Matt 

PS This will eventually have other spokes attached to it. Just troubleshooting between two right now. Just putting that out there in case you are wondering about why I asked about multi-point.

[Georg Pauwen]

Hello,

both your routers are not running OSPF. Between which devices do you want to form an OSPF adjacency ?

[balaji.bandi]

Just to understand better do you have high level diagram of network.

From waht device to waht device you try to enable OSPF, what devices in the path

Can you post show ip interface ospf  on the OSPF devices ?

[gunnydaman]

I am trying to form an adjacency from the two L3 switches. Here is the diagram and configs you are asking for.

PEER:

SWITCH_PEER1#sh ip ospf interface
Loopback0 is up, line protocol is up
Internet Address 10.100.0.2/28, Area 0, Attached via Network Statement
Process ID 10, Router ID 10.100.0.2, Network Type LOOPBACK, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Loopback interface is treated as a stub Host

HUB:

sh ip ospf interface
Vlan20 is up, line protocol is up
IP address 192.168.210.1/28
Process ID 10 VRF default, area 0.0.0.0
Enabled by interface configuration
State DR, Network type BROADCAST, cost 40
Index 3, Transmit delay 1 sec, Router Priority 1
Designated Router ID: 10.100.0.1, address: 192.168.210.1
No backup designated router on this network
0 Neighbors, flooding to 0, adjacent with 0
Timer intervals: Hello 10, Dead 40, Wait 40, Retransmit 5
Hello timer due in 00:00:00
No authentication
Number of opaque link LSAs: 0, checksum sum 0
Vlan10 is up, line protocol is up
IP address 192.168.110.1/27
Process ID 10 VRF default, area 0.0.0.0
Enabled by interface configuration
State DR, Network type BROADCAST, cost 40
Index 2, Transmit delay 1 sec, Router Priority 1
Designated Router ID: 10.100.0.1, address: 192.168.110.1
No backup designated router on this network
0 Neighbors, flooding to 0, adjacent with 0
Timer intervals: Hello 10, Dead 40, Wait 40, Retransmit 5
Hello timer due in 00:00:01
No authentication
Number of opaque link LSAs: 0, checksum sum 0
loopback0 is up, line protocol is up
IP address 10.100.0.1/28
Process ID 10 VRF default, area 0.0.0.0
Enabled by interface configuration
State LOOPBACK, Network type LOOPBACK, cost 1
Index 1

[paul driver]

Hello
I am not able to view your configs at this time

However usually with ospf adjecencys not forming especially between switches is a result of mtu or ospf network type mismatch

So make sure you have the correct ospf interface network type on both switches and disable the mtu check with ip ospf mtu ignore command

[gunnydaman]

Added the no ip ospf mtu ignore on ospf related interfaces. Still no adjacency.

[Georg Pauwen]

Hello,

if your setup is:

Switch_Peer1 --> PEER_VPN_ROUTER --> HUB_VPN_ROUTER --> NEX_SWITCH

both switches will never be able to form an adjacency. Is that what you are trying to accomplish ?

[gunnydaman]

Yes, that is what I am trying to accomplish. Can you explain the reason the two switches will never form an adjacency? 

[Georg Pauwen]

Hello,

as far as I can tell, the two switches are not directly connected, there is no common network, so they won't be able to form an adjacency.

[balaji.bandi]

you need to read the OSPF Guidelines and Limitation, OSPF can join or form a network neighbour with disjoin network

[Georg Pauwen]

So how do you get both switches to form an adjacency ?

[Richard Burts]

Another issue is that, according to the output of show ip ospf interface, that the SWITCH_PEER is running OSPF on a loopback interface. While it is certainly valid to run OSPF on loopback interfaces (if you  want OSPF to advertise that subnet) OSPF will never form any adjacency using the loopback interface. 

[paul driver · Accepted solution]

Hello
After reviewing your configuration files, you dont have any reachability between those two switchs, and the reason for that is the hub rtrs are not aware of the switchs loopbacks addresses.

So you need to advertised those switch loopbacks subnets to each hub rtr and then once the switchs have reachability to each other via their loopbacks then you need to create a basic GRE tiunnel for OSPF connectivity and you should then be able to advertised the each switches vlans over the ospf 10 area adjacency. .

Review the attached for the configuration required, which basically shows what i have explained.
Ive change the subnet mask on the loopback interfaced of each  to a /32, then appended a static route on each hub rtr so they know how to reach those loopbacks and then redistributed those static routes into eigrp. between each eigrp hub rtr, and lastly created of a gre tunnel on each switch for ospf connectivity sourced from each loopback.

[paul driver · Accepted solution]

@gunnydaman 

I am assuming my suggestion was applicable to solving this connectivity issue?

Thanks for the rating and marking the post as solved 

[gunnydaman]

I had to adjust the source address on the GRE tunnel to use the loopback address, but other then that the settings you provided did the trick. Thanks for all the help.