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Router interconect - URGENT

Hi experts!

I am wondering if the following setup is possible:

We currently have this:
   Isp
     |
Router1
     |   LES line (fibre) Trunk
     |  
2950 switch


We are getting a second location and would like to connect with the above setup. I was wondering if it is possible to setup a trunk (through a leased line) from the new location to the 2950 switch(above) so we can get to router1 or is that not good practise. i.e.

  Isp
     |
Router1
     |  
     |    LES line (fibre)
     |                   LES line2
2950 switch ------------------------ Router2

Is this possible at all or should we have the LES line connecting the 2 routers directly? We just need to point a default from router2 to router1.
0
mmbecks7
Asked:
mmbecks7
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2 Solutions
 
dhoffman_98Commented:
This is going to depend on what subnet the switch is on, and you would need to provide additional information to get a more complete picture.

Let's say the interface on the 2950 side of Router 1 is 10.5.1.0/24. The same subnet has to be used for the interface on the 2950 side of Router 2. If not then the two subnets will never communicate with each other because the switch is a switch... not a router.

If the 2950 was replaced with a router, then you could do something like that because the connection from each router would go to individual interfaces with their own IP Address, and on their own subnets.

The problem with putting both routers on the same subnet is that there is no way for traffic on the subnet to know which router to talk to.

What may work better is run the new circuit from Router 2 to a second interface on Router 1. Then Router 1 would have to be configured with a route for the network that is served by Router 2 so that clients in your network (on the 2950 switch) would be routed to the site on Router 2 if their destination address was on that router. If not then they could be routed out to the ISP on the other interface.

But then you have to question if you even need a Router 2. Figure you have the ISP on the outside, connected through Router 1. If Router 1 has more than one interface on the inside, then you can connect one leased line to one interface, and the new leased line to the other. Then each network would have their own subnets, and you set up your routes in the router so that traffic for network 1 goes out interface 1 and traffic for network 2 goes out interface 2... all other traffic goes out the default to the internet. Something like this:

                   ISP
                     |
                     |
         WAN Interface
                     |
                     |
                Router
                 /      \
                /        \
Interface1           Interface2
       |                           |
       |                           |
  Circuit1                Circuit2
       |                           |
       |                           |
 Network1            Network2



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pseudocyberCommented:
I would recommend doing it this way:

  Isp
     |
Router1------------------------ Router2
     |  
     |    LES line (fibre)
     |                   LES line2
2950 switch
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mmbecks7Author Commented:
Thanks for the replies...Yes the routers would be on the same subnet...The ultimate goal is to have this:

Isp1  
     |
Router1                            
     |                                                    Isp2
     |    LES line (fibre)                            |
     |                   LES line2                      |
2950 switch ------------------------ Router2

Router 2 points a default to router one as primary and another default to isp2 with a higher metric as backup. Would that be possible with this setup? Or should connect router to router?
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pseudocyberCommented:
I would make the "WAN" (LES) line a different subnet, so you don't have broadcast traversing it.  Is there some need to make it the same segment?
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mmbecks7Author Commented:
Not really, only that it costs less to get the circuit to the 2950 from router2 rather thn to router1...But if router to router works better then we can go for that....Final thoughts? :)
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dhoffman_98Commented:
I have nothing else to add. It looks like pseudocyber's solution is the same as mine, I just added the extra interfaces, but the end result is the same. I'm not sure about mmbeck's. It looks like what you originally created but mentions creating two default routes. I don't think you can do that. Default is default, regardless of metrics. However you can create two static routes and set different metrics, but I don't think that falls into what you are looking to accomplish.
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mmbecks7Author Commented:
Is it not possible to have this for example:

ip route 0.0.0.0 0.0.0.0 router1 10
ip route 0.0.0.0 0.0.0.0 router2 30

So traffic would go through router1 and router2 is backup??
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dhoffman_98Commented:
Where would you be configuring that? If you are configuring it on the routers then where is the traffic being forwarded to? These lines say to send traffic to router1 and then if it fails, then send it to router2. But if this configuration is ON router1, it can't redirect traffic back to router2 on the same interface that the traffic was coming from.

On the other hand, if you have a client on the network that has access to both routers you could do that. Say you have an XP workstation on the network. You could manually set static routes like that with two metrics. That way it's the IP Stack on the workstation that determines where to send it before it even gets to the router.
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mmbecks7Author Commented:
This would be on router2 with a second connection to isp2 on a different interface:

ip route 0.0.0.0 0.0.0.0 isp1 IP 10
ip route 0.0.0.0 0.0.0.0 isp2 IP 30
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dhoffman_98Commented:
Then that's what I'm saying. It won't work that way. You are saying that you want to create a route on router2 that says the traffic should go back to router1. Look at it this way. The router has an internal interface on your network, and an external interface to the ISP. What you are saying is that traffic that was sent to the router to go out to the ISP is going to get sent back to the other router. It doesn't work that way unless the next hop is on the other interface... and it isn't. It's the clients on your network that will determine which router to talk to... not the router. Once the traffic gets to the router with an external destination, it will go outside.

Again, if you want to set something like that up, you'll need to set the two routes on each client and set the appropriate metrics there.
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mmbecks7Author Commented:
Hi

Thanks for that...The connection from router2 to router1 would be a trunk on a vlan with an external ip address and not an internal one...Would it still not work?? Mind you the routers are cisco 6500's and do have multiple vlans on them (so getting traffic in and out is not an issue). What u r saying is that the routers have to be directly connected to each other with 2 separate interfaces for each connection?
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dhoffman_98Commented:
If they are multiple vlans and can therefore have individual subnets, then you potentially CAN do it that way. It's just  matter of the basic function of a router. It looked like you were trying to take traffic from one segment "segmentA" which had a default gateway pointing to router1, and then having router1 send that traffic back over the same segment to another gateway interface on segment2. While it looks like it could work, you are asking the router to bounce traffic back out the same interface that it came in from, and I don't thing that works.
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