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Beginner

My network is going crazy (Static Routing)

Hello everyone,

 

So I have this network. However I think I must have done something to the static routing because right now the packets doesnt take that shortest way possible but insted some random way, sometimes it doesnt ever reach its destination. Also, all of my routers each have like 12+ static routing connections, is that normal?

7d3702ec92aefe0838dd54b6b7a68c68

 

 

I don't really know what I should do with that static routing. Also, the PC:s on one of the side can't talk to the other side. 

 

So my questions is:

* What should I do to make my static routing stable

* What should I do to make the PC:s talk to eachother

 

Thank you!

 

/Greg

1 ACCEPTED SOLUTION

Accepted Solutions
VIP Collaborator

Re: My network is going crazy (Static Routing)

I would assume things are more stable now that the duplicate static routes have been removed.

 

If you are saying you don't see anything reroute if you drop a link, that is probably because the static routes have a higher priority (lower administrative distance) and will override the OSPF routes.

1. For this to work, ALL the routers must be configured with OSPF, including R1 & R8.

2. Make sure you are seeing the proper OSPF neighbors on all routers (show ip ospf neighbor)

3. Make sure you are seeing OSPF routes on all routers (show ip ospf routes)

4. If by chance you are OSPF peering across the switch in the middle of the four routers, eliminate that as it will only confuse things.

5. If all the above look OK, then remove the static routes and OSFP should then take over. (This will probably impact traffic during the transition.

6. Do "show ip route" and all the routes should now be OSPF routes (except the directly connected interfaces).

 

 

20 REPLIES 20
VIP Collaborator

Re: My network is going crazy (Static Routing)

So if I understand you correctly, you have four main routers each with about 12 static routes? If that is the case, it really doesn't sound like that is anything out of the ordinary or excessive. If anything it probably could be considered a small deployment.

Perhaps if you could provide the router configs it would be easier to identify what is happening. At the very least a listing of the static routes for each router.

On the surface, I can see how things could get "confused" with the current configuration of the routers with their direct links between each other and the connection to the switch which I assume is a common network. Seems it would be prone to routing loops or packets taking sub-optimal paths.

Finally, static routing is just that. If an interface is up, it will route packets as directed by the static routes, regardless if the next hop IP is available. So traffic could be black holed. There are some ways around it, but that in itself complicates things. You may want to consider implementing a dynamic protocol such as EIGRP or OSPF which would more than likely solve these issues.

But for now, if you could provide the requested info we can see about helping with your issues.

Regards

Beginner

Re: My network is going crazy (Static Routing)

Thank you for your answer!

So, I havent done anything static routing with the switch in the middle yet. I want to sort this out first.

 

Here are the static routing:

Center1:

192.168.20.0/24 via 192.168.10.2

192.168.20.0/24 via 192.168.40.1

192.168.30.0/24 via 192.168.10.2

192.168.30.0/24 via 192.168.40.1

192.168.50.0/24 via 192.168.10.2

192.168.50.0/24 via 192.168.40.1

192.168.55.0/24 via 192.168.10.2

192.168.55.0/24 via 192.168.40.1

192.168.60.0/24 via 192.168.10.2

192.168.60.0/24 via 192.168.40.1

192.168.65.0/24 via 192.168.10.2

192.168.65.0/24 via 192.168.40.1

192.168.100.0/24 via 192.168.10.2

192.168.100.0/24 via 192.168.40.1

 

 

Center2:

192.168.30.0/24 via 192.168.20.2

192.168.30.0/24 via 192.168.10.1

192.168.40.0/24 via 192.168.20.2

192.168.40.0/24 via 192.168.10.1

192.168.100.0/24 via 192.168.20.2

192.168.60.0/24 via 192.168.20.2

192.168.65.0/24 via 192.168.20.2

192.168.55.0/24 via 192.168.50.2

192.168.100.0/24 via 192.168.10.1

192.168.60.0/24 via 192.168.10.1

192.168.65.0/24 via 192.168.10.1

 

Center3:

192.168.40.0/24 via 192.168.30.2

192.168.10.0/24 via 192.168.20.1

192.168.50.0/24 via 192.168.20.1

192.168.55.0/24 via 192.168.20.1

192.168.65.0/24 via 192.168.30.2

192.168.60.0/24 via 192.168.30.2

192.168.40.0/24 via 192.168.20.1

192.168.10.0/24 via 192.168.30.2

192.168.50.0/24 via 192.168.30.2

192.168.55.0/24 via 192.168.30.2

192.168.65.0/24 via 192.168.20.1

192.168.60.0/24 via 192.168.20.1

 

Center4:

192.168.10.0/24 via 192.168.40.2

192.168.20.0/24 via 192.168.30.1

192.168.50.0/24 via 192.168.30.1

192.168.100.0/24 via 192.168.30.1

192.168.65.0/24 via 192.168.60.2

192.168.55.0/24 via 192.168.30.1

192.168.50.0/24 via 192.168.40.2

192.168.10.0/24 via 192.168.30.1

192.168.20.0/24 via 192.168.40.2

192.168.100.0/24 via 192.168.40.2

192.168.55.0/24 via 192.168.40.2

 
Highlighted
Beginner

Re: My network is going crazy (Static Routing)

Looking at your routing, you are trying to use both paths around the edge of your central routing environment on all routers. This means that for packets arriving at router 2 bound for 192.168.65.1, half will be sent to router 1 and half to router 3. Of the packets sent to router 1, half will be sent correctly to router 4 and the other half will be returned to router 2!

 

A quick fix would be to remove the statics that go the wrong way around the loop e.g. 

 

Center1: 192.168.65.0/24 via 192.168.10.2

 

... but ultimately I recommend that you set up a simple dynamic routing protocol on all of the routers and get rid of all of the statics.

 

There are lots of online guides for this. I suggest that you look at EIGRP or OSPF in the first instance.

 

Hope this helps

 

Dave

VIP Collaborator

Re: My network is going crazy (Static Routing)

Hello,

It's easy to see the issue here. Your static routes point in two different directions around the ring, so each router has two routes to a destination. By default they will load share across both, so to illustrate, while Center 1 is sending packets for 192.168.55.x to Center 4, Center 4 may be sending packets to the same destination to Center 1. So the packets end up going nowhere.

The simplest fix would be to define a single route with the statics. One direction around the ring. That will get you stability. The redundancy will be lost and any fix to a lost link or router would be a manual re-route. But that's better than having problems any day. That's the disadvantage of static routing.

 

Implementing OSPF or EIGRP would be the way to go.

 

Hope this helps.l

 

Beginner

Re: My network is going crazy (Static Routing)

Thank you for you answer,

 

However, I don't know how to implement OSPF or EIGRP and I've been unable to find any good tutorials on how to do it.

 

/Greg

VIP Collaborator

Re: My network is going crazy (Static Routing)

Your first order of business should be to stabilize the network, so suggest implementing the suggested fix with the statics.

If your network is just what is in the diagram, implementing OSPF or EIGRP would not be a large undertaking. Understand that EIGRP is Cisco proprietary and only works with Cisco routers, OSPF is an industry standard and could work in a multi-vendor environment.

For OSPF, in it's most basic form, you need to identify an area and the networks you want to peer across for establishing OSPF neighbors as well as the other networks you wish to advertise. For your network, making everything area 0 and if it is all 192.168.x.x address space, then the configuration on each router would be as simple as:

!
router ospf 100
 network 192.168.0.0 0.0.255.255 area 0
!

OR IF YOU CHOSE TO DO IT ON A MORE GRANULAR BASIS:

!
router ospf 100
 network 192.168.10.0 0.0.0.255 area 0

 network 192.168.40.0  0.0.0.255 area 0
!

You just need to specify the networks associated with that particular router.

 

Here is a link for OSPF, this document is one of the better ones and has been around forever.

https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html

 

Hope this helps

 

 

 

 

 

 

Beginner

Re: My network is going crazy (Static Routing)

Thank you for your respons!

 

I did network 192.168.0.0 0.0.255.255 area 0 on the routers and remove the dupletts of static routing on each router, I don't really see any change besides that its no longer going into weird directions, if I for example cut a wire of, the package won't take a different route. 

VIP Collaborator

Re: My network is going crazy (Static Routing)

I would assume things are more stable now that the duplicate static routes have been removed.

 

If you are saying you don't see anything reroute if you drop a link, that is probably because the static routes have a higher priority (lower administrative distance) and will override the OSPF routes.

1. For this to work, ALL the routers must be configured with OSPF, including R1 & R8.

2. Make sure you are seeing the proper OSPF neighbors on all routers (show ip ospf neighbor)

3. Make sure you are seeing OSPF routes on all routers (show ip ospf routes)

4. If by chance you are OSPF peering across the switch in the middle of the four routers, eliminate that as it will only confuse things.

5. If all the above look OK, then remove the static routes and OSFP should then take over. (This will probably impact traffic during the transition.

6. Do "show ip route" and all the routes should now be OSPF routes (except the directly connected interfaces).

 

 

Beginner

Re: My network is going crazy (Static Routing)

Thank you! It's working perfectly!

 

I just have a little question, is there a way to include the switch in the middle for this? So it could take the middle route, do i need to change the switch to a router?


Thanks again!

 

 

VIP Collaborator

Re: My network is going crazy (Static Routing)

Very glad to hear everything is working. Congratulations on your OSPF deployment.

You could add the switch in. Just make it a common network (VLAN) for all four routers and they should peer across it.

What may happen as a result is that it may become the preferred path for many of the routes if it is a higher bandwidth than the point to points. (Look at OSPF costing in the link I provided).

Thank you for the votes.

Beginner

Re: My network is going crazy (Static Routing)

Thank you for your respons!

 

Sorry, but I don't really understand how to make the VLAN for all the four routers.

VIP Collaborator

Re: My network is going crazy (Static Routing)

Is it a Cisco switch with a default configuration and only being used for the routers?

If so, assign the router interfaces a common network and plug them into the switch and it should just work as by default all the switch ports are in the default VLAN 1.

 

If it is a Cisco switch and you want to create a unique VLAN for these routers:

!
conf t
!
!
! CREATE A UNIQUE VLAN
!
vlan 2
!
! GIVE IT A NAME (OPTIONAL)
!
name ospf_lan
!
exit
!
! ASSIGN THE VLAN TO INTERFACES
!
interface f7/1
 switchport mode access
 switchport access vlan 2
 spanning-tree portfast
!

Beginner

Re: My network is going crazy (Static Routing)

It is a switch-PT. I did as you said, but it doesn't work, when I cut the wires except the one to the switch the package just stopps at the router.

VIP Collaborator

Re: My network is going crazy (Static Routing)

What did you do, just plug into the switch with default config or create a unique VLAN?

 

Thanks

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