I'm in early stage of configuring a ASA-5520 box for remote VPN access w/ IPSec. I'm trying to enable ISAKMP on the "outside" interface (with vlan).

The outside interface would be the sub-interface 802.1Q for a redundant interface.

                   | === Gi0/0 === < --- > Switch #1

                   |           |

ASA-5520 ==           | +++ Redundant1 +++  Redundant1.251 (vlan251 outside)

                   |           |

                   | === Gi0/2 === < --- > Switch #2

Cisco Adaptive Security Appliance Software Version 8.3(1)4
Device Manager Version 6.3(1)

The command wouldn't succed since the interface does not have a "nameif" (as suggested by cisco.com). If I do set a "nameif" then the redundant interface will pass untagged packets.

The command is "crypto isakmp enable interface-name"

It would be: crypto isakmp enable Redundant1.251 but

Here is my run conf:

interface GigabitEthernet0/0
description Switch_#1
duplex full
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/1
description *** not used ***
duplex full
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/2
description Switch_#2
duplex full 
no nameif   
no security-level
no ip address
!            
interface GigabitEthernet0/3
description *** not used ***
duplex full 
shutdown    
no nameif   
no security-level
no ip address

!

interface Management0/0
description mgt-vlan
nameif inside
security-level 100
ip address 172.19.24.66 255.255.254.0
management-only
!
interface Redundant1
description Switch_#1_#2
member-interface GigabitEthernet0/0
member-interface GigabitEthernet0/2
no nameif
no security-level
no ip address
!
interface Redundant1.251
description vlan251
vlan 251
no nameif
security-level 100
ip address "outside_ip" 255.255.255.