Replacing Static Routes with OSPF implementation

Member_2_3766735
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Hello,

I have 3 sites that have been set up with Cisco 2600s and 2800s. At the moment, we have static routes implemented, they work fine. In an effort to be more effective, we want to replace the statics with dynamic. OSPF seems to be the right direction.


Site1
router1 fa0/0 192.168.3.x fa0/1 192.168.1.x
router2 fa0/0 192.168.6.x fa0/1 192.168.1.x

Site2
router1 fa0/0 192.168.6.x fa0/1 192.168.4.x
router2 fa0/0 192.168.7.x fa0/1 192.168.4.x

Site3
router1 fa0/0 192.168.7.x fa0/1 192.168.2.x
router1 fa0/0 192.168.5.x fa0/1 192.168.2.x secondary
router2 fa0/0 192.168.6.x fa0/1 192.168.2.x

Site1Router1 is connected to Site2Router1 via Fastethernet 0/0
Site2Router2 is connected to Site3Router1 via Fastethernet 0/0
Site3Router2 is connected to Site1Router2 via Fastethernet 0/0

The fa0/1 of Router1 and Router2 at each site are connected to a switch at the sites.

Different IP schemes at the 3 sites.

Site1Router1

router ospf 1
network 192.168.1.0 0.0.0.0 area 0
network 192.168.3.0 0.0.0.0 area 0

Site1Router2

router ospf 1
network 192.168.3.0 0.0.0.0 area 0
network 192.168.6.0 0.0.0.0 area 0

Site2Router1

router ospf 1
network 192.168.6.0 0.0.0.0 area 0
network 192.168.4.0 0.0.0.0 area 0

Site2Router2

router ospf 1
network 192.168.7.0 0.0.0.0 area 0
network 192.168.4.0 0.0.0.0 area 0

Site3Router1

router ospf 1
network 192.168.7.0 0.0.0.0 area 0
network 192.168.5.0 0.0.0.0 area 0
network 192.168.2.0 0.0.0.0 area 0

Site3Router2

router ospf 1
network 192.168.1.0 0.0.0.0 area 0
network 192.168.2.0 0.0.0.0 area 0

OSPF doesn't work. Please help. Thank you.
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Instructor
Top Expert 2015
Commented:
How are these sites connected? Frame-relay?

You OSPF network statements don't look consistent with your topology and are missing the last octet.

For example, Site 1/Router 1:

network 192.168.1.1 0.0.0.0 area 0
network 192.168.3.1 0.0.0.0 area 0

Site 1/Router 2:
network 192.168.1.2 0.0.0.0 area 0
network 192.168.6.2 0.0.0.0 area 0

It doesn't appear that site 1 router 2 is connected to the 192.168.3.0 network. As such, you don't need a network statement of 192.168.3.x
Top Expert 2004

Commented:
Your network statements should match the actual configured subnets on the routers. the main reason your ospf doesn't work though is that the mask bits are wrong. Try (for example)
network 192.168.1.0 0.0.0.255 area 0
or do what donjohnston suggested above.

Why is there a secondary address at Site 3? Unless it has a known purpose, remove it.

Author

Commented:
The sites are connected via fiber.

I thought that the last octet in describing a network is 0.

You're right, the Site1Router2 is not connected to the 192.168.3.0 network. Site1Router1 is connected to that network.

The actual configured subnets at the 3 sites are 255.255.255.252 on the inside (fa0/1). The subnet configured at the sites between the routers is 255.255.255.0 (fa0/0). That holds true for each router at each site.

The secondary address is needed.

I appreciate your quick response. But, I need to have this working by tomorrow, or I'm in trouble :)

Thanks again.
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Don JohnstonInstructor
Top Expert 2015

Commented:
You can take the real easy way out...

On every router use the network statement:

network 192.168.0.0 0.0.255.255 area 0

it ain't pretty, but it'll work.
Top Expert 2004

Commented:
Yep, that would do it...

Author

Commented:
Would I be leaving the static routes in place, while I configure OSPF, and then remove the statics?

That's what I have right now, and the computers behind SIte1Router1 cannot ping the computers behind Site3Router1.

Please give me a 2-3 liner on your take on OSPF. What it does to the routes and how does the router understand the various packets going through it.

Thanks.
Don JohnstonInstructor
Top Expert 2015

Commented:
>Would I be leaving the static routes in place, while I configure OSPF, and then remove the statics?

Sure. There's nothing wrong with that.

>That's what I have right now, and the computers behind SIte1Router1 cannot ping the computers behind Site3Router1.

Please post the routing tables for S1R1 and S3R1. (show ip route)

Top Expert 2004

Commented:
I suspect you're just missing a static route at the moment. OSPF will take care of that problem because all routers will know about all configured networks.

OSPF is a means of communication between the routers so that they know about each other's configured networks. The protocol includes a means of exchanging database information, and any changes are immediately communicated to "neighbors." That's why properly configuring the network statements is critical- they tell the routers both what networks to advertise and on which networks to advertise.

Author

Commented:
So, if I don't tell one of my routers that it has to advertise a particular network, then the router would not even learn or know that network by itself?

I have to get rid of some static routes on the routers. For example, in Site1:

Site1Router1

router ospf 1
network 192.168.1.0 0.0.0.255 area 0
network 192.168.3.0 0.0.0.255 area 0

Site1Router2

router ospf 1
network 192.168.3.0 0.0.0.255 area 0
network 192.168.6.0 0.0.0.255 area 0

Those statements mean that I have configured my routers to advertise those networks to the other routers. Networks 1, 3, and 6 are advertised out. I have static routes for 192.168.89.0 and 192.168.90.0 also on those routers. Should I then configure the routers with

network 192.168.89.0 0.0.0.255 area 0
network 192.168.90.0 0.0.0.255 area 0

?

Thank you all for your valuable inputs.
Top Expert 2004
Commented:
No, the router will automatically learn about all routes advertised by others. You make network statements only for locally connected subnets, which is what you have above for Site 1. Otherwise it's no better than static routes :-)

The routers that "own" 192.168.89.0 and 192.168.90.0 should advertise those networks by making network statements for those as well as for the interfaces on which they need to advertise.

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