I have an ASA 5510 running 8.2(5) with the following configuration and I am having problems routing traffic between sub-interfaces at the same security level. Although not shown there are ACL's for each sub-interface allowing ICMP and IP traffic in both directions. NOTE: I have cut down the amount of config posted but what is there should be sufficient.

The restrictions in place are: No upgrade beyond 8.2(5) No use of same-security commands All inside interfaces to be same security level.

Traffic flows to/from the outside to the various sub-interface, but between sub-interfaces it is hit & miss, which is the source of my confusion. If it were consistent in not working it would be easy.

The problems I am seeing for example are:

  1. Asymmetric NAT rules matched for forward and reverse flows; for traffic from sub-int 112 to 104
  2. ICMP traffic being denied by an implicit rule, yet each ACL has ext perm ICMP any any
  3. I am pretty sure this line nat (DMZ-102) 1 is an error but having it or removing it seems to make no difference.

So if anyone has suggestions/recommendations please let me know.

interface Ethernet0/0
 speed 100
 duplex full
 nameif outside
 security-level 0
 ip address 

interface Ethernet0/1
 speed 1000
 duplex full
 no nameif
 no security-level
 no ip address

interface Ethernet0/1.102
 vlan 102
 nameif DMZ-102
 security-level 100
 ip address 

interface Ethernet0/1.103
 vlan 103
 nameif DMZ-103
 security-level 100
 ip address 

interface Ethernet0/1.104
 vlan 104
 nameif DMZ-104
 security-level 100
 ip address 

interface Ethernet0/1.112
 vlan 112
 nameif DMZ-112
 security-level 100
 ip address 

access-list incoming extended permit ip any any
access-list OUTBOUND extended permit ip any any 
global (outside) 1 interface
global (DMZ-102) 1 interface
global (DMZ-103) 1 interface
global (DMZ-104) 1 interface
global (DMZ-112) 1 interface
nat (DMZ-102) 1
nat (DMZ-102) 0
nat (DMZ-103) 0
nat (DMZ-104) 0
nat (DMZ-112) 0
static (DMZ-103,outside) netmask 
static (DMZ-102,DMZ-103) netmask
static (DMZ-102,DMZ-104) netmask
static (DMZ-102,DMZ-112) netmask
static (DMZ-103,DMZ-102) netmask
static (DMZ-103,DMZ-104) netmask
static (DMZ-103,DMZ-112) netmask
static (DMZ-104,DMZ-102) netmask
static (DMZ-104,DMZ-103) netmask
static (DMZ-104,DMZ-112) netmask
static (DMZ-112,DMZ-102) netmask
static (DMZ-112,DMZ-103) netmask
static (DMZ-112,DMZ-104) netmask
access-group incoming in interface outside
access-group OUTBOUND out interface outside
route outside 1
  • Why wouldn't you be able to use same-security commands?
    – Eddie
    Nov 10, 2014 at 4:05
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 10, 2017 at 23:14

1 Answer 1


Without the use of same-security, traffic will not flow between interfaces at the same security level. That's the way it's designed, and the very purpose of those commands. No amount of ACLs can override that basic function. Once inter-interface/intra-interface is enabled -- thus allowing traffic at all -- ACLs will apply.

(You could set interfaces to different levels and use NAT/ACLs to control the traffic, but your restrictions don't allow that either. And it's a mess to maintain.)

  • Thanks Ricky. I understood that you needed ACL's if you were not using the same-security commands, i.e. the commands were optional. So Nov 10, 2014 at 19:05
  • Thanks Ricky. I obviously have misunderstood the same-security commands, thinking they were optional and avoided the need for ACL's. So on the basis that they are required and given that I am doing static NAT do I need any additional NAT or Global statements to those I already have for inter VLAN routing? It also occurs to me that since I am using sub-interfaces for VLAN's do I need both inter and intra traffic allowed? Nov 10, 2014 at 19:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.