Is it possible to have a dynamic and static VPN between the same IOS router and ASA, sharing same interesting traffic/crypto ACL on the ASA end? The two devices in question:
- ASA 9.1 - hub/termination point for VPNs
- 897 15.4 - spoke/branch office
The 897 IOS router has two links for internet connectivity:
- Primary link: static IP 18.104.22.168, ATM0 tied to Dialer2 (default route injected via 'ppp ipcp route default', static AD 1)
- Backup link: dynamic IP, Cell0 tied to Dialer1 (floating static default route with AD 200 for when ATM0/Dialer2 interfaces go down)
There is a single network - 10.1.30.0/24 at the branch office. A static L2L VPN (22.214.171.124 for examples sake) is configured over ATM0 link to the ASA and is working successfully. In the event this link/tunnel goes down I want the branch office to maintain reachability back to our corporate networks via the dynamic VPN tunnel over the Cellular 4G backup link.
Currently both the static and dynamic VPN's have identical local and remote networks in their crypto ACL's.
Relevant ASA configuration:
crypto dynamic-map BACKUPCELL 16 match address CRYPTOACL_CELL crypto dynamic-map BACKUPCELL 16 set pfs group5 crypto dynamic-map BACKUPCELL 16 set ikev1 transform-set ESP-AES-256-SHA crypto dynamic-map BACKUPCELL 16 set reverse-route " crypto map outside_map 11 match address CRYPTOACL_ATM crypto map outside_map 11 set pfs group5 crypto map outside_map 11 set peer 126.96.36.199 crypto map outside_map 11 set ikev1 transform-set ESP-AES-256-SHA crypto map outside_map 11 set reverse-route " crypto map outside_map 16 ipsec-isakmp dynamic BACKUPCELL access-list CRYPTOACL_ATM extended permit ip any4 object 10.1.30.0_24 access-list CRYPTOACL_CELL extended permit ip any4 object 10.1.30.0_24
The issue I am facing when attempting to test a failover scenario by dropping the ATM0 link on the 897, 'show crypto ipsec sa' on the ASA shows decrypts but no encrypts (packet-tracer shows a DROP on ENCRYPT phase). It appears even with the static peer down, when evaluating the ASA's crypto map sequence it is stopping at the CRYPTOACL_ATM match for the static peer.
If I modify the ASA's CRYPTOACL_ATM to be something else specific, causing the CRYPTOACL_CELL to be matched it works successfully. It's not feasible as the branch office will need to access all networks over it's Cell0 link if ATM0 goes down.
Is there a possible solution with this topology and policy based VPN's on ASAs? (That doesn't involve a second ASA head end, or replacing it with something that supports route based VPNs.)
Thank you in advance.