connecting remote sites using wan interface to work as a lan

[wesleyjay]

Hi,

We have a cisco 1700 series and two 2500 series these routers connect our three branches using leased line. presently each branches have different subnet. eg. Branch1 - 192.168.0.0/255.255.255.240, Branch 2 - 192.168.0.32/255.255.255.240, Branch 3 - 192.168.0.64/255.255.255.0. we would like to change change the setup that all our branch will be on the same network eg. 192.168.0.0/255.255.255.0. our purpose is to connect our 3 branches like a single lan. based from my readings what we need is bridging, is this what we are looking for? can you give me sample configuration on this kind of setup?

TIA,

Wesley

[mark.mcsherry]

Hi Wesley,

Are you sure you want to bridge? It's normal to have the setup you have and in some ways, moving to bridging would be seen as a backward step, as it's less efficient.

That said, you'll need something similar to this listed below. I've not tested this out, so you might want to lab it up if you can.

Check out the doc CD too:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fibm_r1/br1fpt1/br1ftb.htm#wp1019692

bridge irb

bridge 1 protocol ieee

interface Serial0

no ip address

bridge-group 1

interface Ethernet0

no ip address

bridge-group 1

You might also need a 'bridge 1 protocol ip'

Mark

[frennzy]

Just to reiterate what Mark said, you should consider why you want to bridge these three sites. You should also consider what impact it will have on your WAN links. If you have slow/low speed interconnections between the three sites, you are going to be sending a lot of unnecessary traffic between them. (ARPs, for example).

What functionality to you gain by bridging these sites? Weigh that against the reduction in performance and efficiency you will see before making a decision.

[wesleyjay]

Hi,

thanks for the quick reply, actually im also against that kind of setup (bridging lan using wan ports) the main reason is we are changing to a new provider and the application we are using is using that kind of setup(bridging). this is only a temporary solution. im thinking of a permanent solution but for now brigding will do,

Wesley

[nleblanc]

You would have to implement a VPN solution which involve the expense of purchasing VPN gateways at each of your sites. But I would like to know why you feel the need to have the 3 sites on the same subnet. The reason routing and subnetting exists is the ease of connecting remote sites.