We currently have several locations where we have Point to Point T1s setup in a star fashion and since they're very low traffic and do not require the sort of high level of availability T1s provide, we want to switch some to VPN. I wish to be able to setup the VPNs in such a way as from the other routers' perspectives everything is the same, so I don't have to reconfigure locations which are just fine with the T1s.
Each location has a Point to Point T1 to central and a cable or DSL connection for all Internet traffic. All of the routers are Cisco 2801 and have VWIX T1 cards and are setup thusly:
The interfaces on either side have 192.168.[location].1 and 192.168.[location].2 for the Point to Point themselves. However the actual networks are 10.[location].x.x. Here's an outlying location and the central location:
[ Outside #5 ]
controller T1 0/1/0 framing esf linecode b8zs channel-group 0 timeslots 1-24 interface FastEthernet0/0 description $$$LAN CONNECTION$$$ ip address 10.5.0.1 255.255.0.0 ip nat inside duplex auto speed auto interface FastEthernet0/1 ip address [IP for ISP] 255.255.255.224 ip access-group 102 out ip nat outside duplex auto speed auto interface Serial0/1/0:0 description $$$CONNECTION TO DOWNTOWN$$$ ip address 192.168.5.2 255.255.255.252 ip route 0.0.0.0 0.0.0.0 [IP for ISP] ip route 10.1.0.0 255.255.0.0 192.168.5.1 ip route 10.2.0.0 255.255.0.0 192.168.5.1 ... ip route 10.6.0.0 255.255.0.0 192.168.5.1 ip route 192.168.1.0 255.255.255.252 192.168.5.1 ip route 192.168.2.0 255.255.255.252 192.168.5.1 ... ip route 192.168.6.0 255.255.255.252 192.168.5.1
[ Central Location ]
controller T1 0/1/0 framing esf clock source internal linecode b8zs channel-group 0 timeslots 1-24 controller T1 0/1/1 ... controller T1 0/2/0 ... controller T1 0/3/0 ... interface FastEthernet0/0 description $$$LAN CONNECTION$$$ ip address 10.1.1.1 255.255.0.0 ip access-group 101 in ip nat inside speed 100 full-duplex interface FastEthernet0/1 description $$$CONNECTION TO GATEWAY ROUTER$$$ ip address 172.16.2.2 255.255.255.252 ip nat outside speed 100 full-duplex interface Serial0/1/0:0 description $$$CONNECTION TO LOCATION 1$$$ ip address 192.168.1.1 255.255.255.252 interface Serial0/1/1:0 description $$$CONNECTION TO LOCATION 2$$$ ip address 192.168.2.1 255.255.255.252 ... ip classless ip route 0.0.0.0 0.0.0.0 [gateway router sends to internet T1 or cable depending various things] ip route 10.2.0.0 255.255.0.0 192.168.1.2 ip route 10.3.0.0 255.255.0.0 192.168.2.2 ... ip route 10.9.0.0 255.255.0.0 192.168.9.2
So, in what way could I setup the VPNs to where they function essentially the same as the T1s from a networking perspective (especially to other locations) where I do not have to renumber or do anything to locations which are fine? I should mention I've never setup a VPN on Cisco previously, I've only done this.