06-16-2003 07:04 AM - edited 03-09-2019 03:41 AM
I am looking for sample configurations for 1700 series router with...
ADSL Internet access
BRI backup (router-to-router)
3DES VPN
Have implemented the ADSL access and VPN but a bit in the dark regarding ISDN backup. Someone suggested I look at GRE and a routing protocol.
Some sample configs would be helpful as I need to add the ISDN backup on a live network. Don't want to mess up.
06-20-2003 08:15 AM
The router generally uses one of these three procedures to monitor the primary connection and initiate the backup connection when needed.
Backup Interface
Floating Static Route
Dialer Watches
You would have to evaluate these and decide which best suits your requirement and implement it accordingly.
Use the information in this document to help your decision.
http://www.cisco.com/warp/public/123/backup-main.html
You can also refer to the following samples for configuration.
http://www.cisco.com/en/US/tech/tk713/tk237/technologies_configuration_example09186a00800a3b77.shtml
http://www.cisco.com/en/US/tech/tk801/tk133/technologies_configuration_example09186a008009455e.shtml
http://www.cisco.com/en/US/tech/tk801/tk379/technologies_configuration_example09186a008010456b
06-20-2003 04:47 PM
The person who suggested the GRE tunnel to support a routing protocol had the right idea. The challenge with a VPN tunnel is to detect when it is down so that an alternate route can be selected. The ADSL interface almost never goes down, so classical dial backup approaches such as backup interface won't work. You must use an approach which tracks availability of the other side based on a routing protocol or "outside information." Cisco does not support the latter (but look at Nexland Pro800 Turbo or Symantec 200R for an example of how it can be done).
Using Cisco kit, your only choice is running a routing protocol, which requires a router at each end of the VPN. You can use BGP directly over the VPN, or any interior routing protocol (EIGRP, OSPF, RIP, etc) over a GRE tunnel. Last time I looked, only the GRE tunnel approach is documented here on CCO, but there is a white paper with an example of each approach on my web site.
Good luck and have fun!
Vincent C Jones
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