Re-establishing VPN connection when ISP forces new IP address

Is the IP address change occurring because you are not keeping the ADSL connection "UP"?

More likely to maintain a consistent dynamically assigned IP with a persistent UP state (i.e.: renew an existing lease vs. trying to lease an IP you previously relinquished).

C> We are using a CISCO router (851) in Greenland to connect to be able

Best Regards, News Reader

| We are using a CISCO router (851) in Greenland to connect to be able | to connect from our facility in Colorado to a GPS receiver in | Greenland. TeleGreenland charges a lot for a fixed IP address using a | ADSL modem, so we are trying to VPN to our facility using the CISCO | router through the much less expensive dynamic IP address option. We | are able to VPN successfully for a short while, but appears the ISP | forces a new IP address every so often, which breaks our VPN tunnel. | So far we have not been able find a solution for re-establishing the | VPN tunnel once the IP address is changed. Does anyone have any | suggestions on how to program the router to circumnavigate this | problem?

What exactly are you using for the tunnel? One approach that would probably work is a multi-point GRE tunnel with NHRP so the dynamic side can update the other end's notion of its address.

Dan Lanciani ddl@danlan.*com

Another option would be to setup the 851 as an EasyVPN client in network-extension mode, to a Cisco device in Colorado acting as the 'server' - but this again assumes the server end has a fixed IP. I would suggest this is OK if you're only connecting two sites - if you want to add more sites connecting to the one in Greenland, then maybe DMVPN (mGRE tunnelling with IPSec profiles as above) is a better way forward.

Cisco IOS IPSec VPN technology page:

Thanks for all of your suggestions. We found a solution to our problem. We setup both Syslog logging and NTP to sync with servers on our VPN-only accessible network, thus forcing the router to re- establish the VPN tunnel if only to sync with the NTP server and deliver logging messages. We are also running a 'kron' a few times a day to ensure the tunnel stays up.

-Thomas

Thanks for all of your suggestions. We found a solution to our problem. We setup both Syslog logging and NTP to sync with servers on our VPN-only accessible network, thus forcing the router to re- establish the VPN tunnel if only to sync with the NTP server and deliver logging messages. We are also running a 'kron' a few times a day to ensure the tunnel stays up.

-Thomas

EasyVPN is a really good option for these scenarios. We use it for many sites that have smaller Cable/DSL based ISPs.