GRE Tunnel Routing Problem

[Andy Guley]

I created a GRE tunnel.  The tunnel is up and functioning fine.  I am having a routing issue on one side of the network.

Router 1

interface Tunnel5

ip address 10.255.111.2 255.255.255.252

ip mtu 1400

tunnel source 10.110.141.254

tunnel destination 10.87.5.2

S     192.168.21.0/24 [1/0] via 10.255.111.1

Router 2

interface Tunnel5

ip address 10.255.111.1 255.255.255.252

ip mtu 1400

tunnel source 10.87.5.2

tunnel destination 10.110.141.254

S    192.168.20.0/24 [1/0] via 10.255.111.2

From router 1 data travels correctly accross the tunnel:

Tracing the route to 192.168.21.254

VRF info: (vrf in name/id, vrf out name/id)

  1 10.255.111.1 12 msec 8 msec 8 msec

  2 10.87.5.9 8 msec *  8 msc

From router 2 it keeps bouncing between the tunnel and serial interface on the router:

traceroute 192.168.20.200

1 10.255.111.2 8 msec 8 msec 8 msec

2 10.110.11.46 16 msec 16 msec 16 msec

3 10.110.11.1 8 msec 8 msec 8 msec

4 10.255.111.2 12 msec 16 msec 12 msec

5 10.110.11.46 24 msec 24 msec 24 msec

6 10.110.11.1 12 msec 16 msec 12 msec 1 10.255.111.2 8 msec 8 msec 8 msec
2 10.110.11.46 16 msec 16 msec 16 msec
3 10.110.11.1 8 msec 8 msec 8 msec
4 10.255.111.2 12 msec 16 msec 12 msec
5 10.110.11.46  24 msec 24 msec 24 msec
6 10.110.11.1 12 msec 16 msec 12 msec

10.110.11.46 is the serial interface on the router where the 10.255.111.2 tunnel is created.  10.110.11.1 is an interface for MPLS.

[JohnTylerPearce]

Andy,

Ok, let me make sure I get this correct.

Is that 'show run int vlan 333' from the Switch or from R1?

If (interface vlan 333) is from R1, can you post the results from 'show int vlan333' ?

[Andy Guley]

vlan333 is the switch hanging off of the router.

[JohnTylerPearce]

Andy,

Ok, Cool. So on R1, there is a physical port that is connected to this switch. On R1, can you post the results from 'show run int X' where X is the port on Router 1 that is going to this SW.

[Andy Guley]

R1

Show run int gi0/1

no ip address

ip flow ingress

ip flow egress

duplex full

speed 100

Here is the config on the switch that it hooks into as well:

interface GigabitEthernet0/1

description CISCO2911 Gig 0/1

switchport access vlan 141

switchport trunk encapsulation dot1q

switchport mode trunk

speed 100

duplex full

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape  10  0  0  0

queue-set 2

mls qos trust cos

auto qos voip trust

rmon collection stats 1 owner PMmonitor

rmon collection history 1 owner PMmonitor buckets 50 interval 1800

[JohnTylerPearce]

Andy,

So when it gets to R1, it's going to do a route lookup, and obviously take the default route, since there is no default route.

On Gi0/1, on R1, configure the IP address of 192.168.20.x, X will be some number that you want to use. Once this happens, it will become a directly connected route.

On R1, after you do this, you will see 192.168.20.0 255.255.255.0, and it will ARP out for any host on 192.168.20.x/24.

Is this switch for testing purposes?

[Andy Guley]

Its not for testing purposes but I can play with it a little.  The swtich is a 3560 and routing is not currently enabled on it.  Can I enable routing on the switch and then put a static route on the router?

Ip route 192.168.20.0 255.255.255.0  via 192.168.20.200?

[JohnTylerPearce · Accepted solution]

Andy,

We'll, this 3560 switch has an SVI on it, so you should be able to put an IP address on R1 and make it a L3 link basically.

you can try that static route command.

[Andy Guley]

Disregard last post.  I created the interface and it is now routing correctly.  I really appreciate all of your help on this issue.

Thank you very much.

[JohnTylerPearce]

Andy,

No problem glad I could help!