Well i think you forgot to post the network diagram, here's a basic configuration that you would require
let the toplogy be like
10.10.10.0/24 --R1 -----R2 ---20.20.20.0/24
Ipsec between R1 and R2 and the subnet between them is 172.16.1.0/30
At R1
crypto isakmp policy 1
encryption 3des
authentication pre-share
hash md5
group 2
crypto isakmp key cisco address 172.16.1.2
crypto ipsec transform-set myset esp-3des esp-md5-hmac
crypto map test 1 ipsec-isakmp
set peer 172.16.1.2
set transform set myset
match address 100
access-list 100 permit ip 10.10.10.0 0.0.0.255 20.20.20.0 0.0.0.255
interface serial 0/0
ip address 172.16.1.1 255.255.255.252
crypto map test
At R2
crypto isakmp policy 1
encryption 3des
authentication pre-share
hash md5
group 2
crypto isakmp key cisco address 172.16.1.1
crypto ipsec transform-set myset esp-3des esp-md5-hmac
crypto map test 1 ipsec-isakmp
set peer 172.16.1.1
set transform set myset
match address 100
access-list 100 permit ip 20.20.20.0 0.0.0.255 10.10.10.0 0.0.0.255
Int serial 0/0
ip address 172.16.1.2 255.255.255.252
crypto map test
The access-list should be mirror images of each other and should have entries for the all the subnets behind the routers for which the traffic needs to be encrypted
Have a look at IPSec on Router to Router at the below link
http://www.cisco.com/en/US/tech/tk583/tk372/tech_configuration_examples_list.html
HTH, rate if it does
Narayan
