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New Member

2 IP classes on the same subnet

Good morning, i've got a problem they i'd liek to share with you.

We have 2 networks , each on a router .

On router 1: 192.168.1.0/24

On Router 2: 172.16.1.0/24

On each router there'ss a switch connected and on each switch there are different servers connected. One of them is 192.168.1.100 ( On router 1) . the thing is that something went wrong on Router 1 and everything just stopped, i have to take this server (192,168.1.100) and connect it to the switch of the router 2 ( different subnet). However, i can't change its IP because dirrefent Remote Clients across the world directly connect to this IP.

What shoul i do to make it work , once i connect it to the switch on router 2 ?

Thanks

3 REPLIES

Re: 2 IP classes on the same subnet

You can try this....

If suppose on Router2, you have interface f0/0 with subnet 172.16.1.0/24

Now you can put a secondary ip on the interface f0/0 as 192.168.1.1

and conect the server 192.168.1.100 in the same vlan/switch to which f0/0 of R2 is connected.

it will something like this

int f0/0

ip address 172.16.1.1 255.255.255.0

ip address 192.168.1.1 255.255.255.0

And also make sure you have proper routing done for the subnet 192.168.1.0/24 towards the router2 and not router1.

Hope this helps.

New Member

Re: 2 IP classes on the same subnet

You can do one thing .

On router 2, u just add the ip address 192.168.1.0/24 as secondary with 172.16.1.0/24

Your both switch will work with the one router 2.

thanks

rajib

Hall of Fame Super Silver

Re: 2 IP classes on the same subnet

Jad

Both of the previous responses assume that you want to move the entire subnet from router 1 to router 2. And if that is the case then the suggestion from rajib is better than the other one since it does correctly advise the new subnet as secondary (the first response just defines 2 primary addresses - and that does not work - you would wind up with only the 192.168.1.0 network on router 2).

But my understanding of your post is that you want to leave network 192.168.1.0 on router 1 and move only the single server. While that can be done, it is somewhat complex and does have some potential negative effect on the network. So before I would move the server I would want to look into what the failure was, and whether there was some way to solve the failure without moving the server to router 2.

But if I were going to move the server (without changing its IP address) here is how I would do it:

- move the server to a connection on the switch connected to router 2.

- on router 1 configure a host specific static route with router 2 as the next hop (for example ip route 192.168.1.100 255.255.255.255 ).

- on router 2 create a subnet that includes 192.168.1.100 as a host address and configure it as a secondary on router 2. (note that having the address as .100 will require a subnet of /29 to make .100 a host address). So configure on router 2 interface

ip address 192.168.1.99 255.255.255.248 secondary

(note that the address on router 2 does not have to be .99, it just has to be something within that subnet which goes from .96 to .103)

This will allow the server to be accessed on router 2 without changing its IP address. Note that one of the negative aspects of this is that the address range from .96 to .103 on router 1 will not be reachable from router 2.

Can you clarify whether my understanding of the problem is correct?

HTH

Rick

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