VPN failover

Here is my set up:
Home office has a T1 and a Cablemodem (When the T1 goes down we route traffic to the cablemodem router).  Each has a cisco 831 router and respectively on our lan.

Remote offices (with cisco 806 or 831's) VPN into the T1 router.

My questions is: With this set up is it possible to have the remote offices establish a vpn with the cablemodem router in the event that the T1 fails?
If not, what kind of setup/hardware would I need to get the desired result here.
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moduloConnect With a Mentor Commented:
PAQed with points refunded (125)

Community Support Moderator
The fact that the traffic is VPN is a side issue.  This is really the same question as fail-over from one ISP to another, which seems to get asked here about once a week.  And there really isn't a cheap answer for incoming traffic.

Does your T1 fail often?  Is there another provider in your area?

friekedAuthor Commented:
Any faults in the T1 are a problem for us, we've already switched from another service provider because they were down too much.

Losses from non-VPN traffic are negligible to us but when our satelite offices lose the connection to our corporate office it causes major problems for us.

We want all of our branch offices (each with a cisco 831) to have 2 ipsec tunnels to the corporate office, one to each of the 2 routers there (831 also).
One of the tunnels would have higher priority and be used as default route to the corporate office and it would only use the 2nd tunnel if the first connection went down for whatever reason.

Please let me know if this could be done with our current setup or if it’s possible with another combination of hardware.  Don't consider money as an issue here in your answer.
friekedAuthor Commented:
I found the answer to my question:
Configuring DPD and Cisco IOS Keepalives with Multiple Peers
in the Crypto Map
To configure DPD and IOS keepalives to be used in conjunction with the crypto map to allow for stateless failover, perform the following steps. This configuration will cause a router to cycle through the peer list when it detects that the first peer is dead.

1. enable

2. configure terminal

3. crypto map map-name seq-num ipsec-isakmp

4. set peer {host-name [dynamic] | ip-address}

5. set transform-set transform-set-name

6. match address [access-list-id | name]

   Command or Action  Purpose  
Step 1

Router> enable
 Enables privileged EXEC mode.

•Enter your password if prompted.
Step 2
 configure terminal

Router# configure terminal
 Enters global configuration mode.
Step 3
 crypto map map-name seq-num ipsec-isakmp

Router (config)# crypto map green 1 ipsec-isakmp
 Enters crypto map configuration mode and creates or modifies a crypto map entry.

•The ipsec-isakmp keyword indicates that IKE will be used to establish the IPSec SAs for protecting the traffic specified by this crypto map entry.
Step 4
 set peer {host-name [dynamic] | ip-address}

Router (config-crypto-map)# set peer
 Specifies an IPSec peer in a crypto map entry.

•You can specify multiple peers by repeating this command.
Step 5
 set transform-set transform-set-name

Router (config-crypto-map)# set transform-set txfm
 Specifies which transform sets can be used with the crypto map entry.

•You can specify more than one transform set name by repeating this command.
Step 6
 match address [access-list-id | name]

Router (config-crypto-map)# match address 101
 Specifies an extended access list for a crypto map entry.
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