How is a layer 3 device aware of what the vlans are at layer 2?  You are
speaking of two different layers.  If a transparent firewall is needs to
bridge the traffic, what is the purpose of a bridge?

 

Regards,

 

Tyson Scott - CCIE #13513 R&S and Security

Technical Instructor - IPexpert, Inc.


Telephone: +1.810.326.1444 
Cell: +1.248.504.7309
Fax: +1.810.454.0130
Mailto:  [email protected]

 

Join our free online support and peer group communities:
<http://www.IPexpert.com/communities> http://www.IPexpert.com/communities

 

IPexpert - The Global Leader in Self-Study, Classroom-Based, Video On Demand
and Audio Certification Training Tools for the Cisco CCIE R&S Lab, CCIE
Security Lab, CCIE Service Provider Lab , CCIE Voice Lab and CCIE Storage
Lab Certifications.

 

From: Kingsley Charles [mailto:[email protected]] 
Sent: Sunday, October 04, 2009 10:57 AM
To: Tyson Scott
Cc: 'Segun Daini; [email protected]
Subject: Re: [OSL | CCIE_Security] Transparent firewall with trunking

 

Hi Tyson 

 

Irrespective of whether the ASA is in Transparent or routed mode, if I need
put the ASA in 

between a trunk link between two switches then it seems ASA should have two
different VLANs.

 

   switch ---- trunk-------------ASA ------trunk-------------switch

 

vlan 2 - 10.20.30.0                                               vlan 6 -
10.20.30.0 

vlan 3 - 20.10.30.0                                                vlan 7 -
20.10.30.0  

 

Does this not break the transparency of the network of bringing two
different vlans for a single subnet?

 

 

With regards

Kings

On Sun, Oct 4, 2009 at 6:53 PM, Tyson Scott <[email protected]> wrote:

Actually the problem is not that you can't do what you are trying to do.
The problem is that you are doing it wrong.

 

The VLAN should be different on each side.  You can't bridge the same VLAN.

 

R1 vlan 2 - 10.20.30.0 - Vlan22 - R2

R3 vlan 3 - 20.10.30.0 - Vlan 33 - R4

 

 

So the configuration would be

 

E0/0

no shutdown

E0/0.2

 vlan 2

E0/0.3

 vlan 3

E0/1

no shutdown

E0/1.22

vlan 22

E0/1.33

vlan 33

 

context TransparentFw1

 allocate-interface E0/0.2

 allocate-interface E0/0.22

context TransparentFw2

 allocate-interface E0/1.3

 allocate-interface E0/1.33

 

Then You assign the Port for R1 to Vlan 2, and R2 to Vlan 22

R3 to Vlan 3, and R4 to Vlan 33

 

 

Regards,

 

Tyson Scott - CCIE #13513 R&S and Security

Technical Instructor - IPexpert, Inc.


Telephone: +1.810.326.1444 
Cell: +1.248.504.7309
Fax: +1.810.454.0130
Mailto:  [email protected]

 

Join our free online support and peer group communities:
<http://www.ipexpert.com/communities> http://www.IPexpert.com/communities

 

IPexpert - The Global Leader in Self-Study, Classroom-Based, Video On Demand
and Audio Certification Training Tools for the Cisco CCIE R&S Lab, CCIE
Security Lab, CCIE Service Provider Lab , CCIE Voice Lab and CCIE Storage
Lab Certifications.

 

From: [email protected]
[mailto:[email protected]] On Behalf Of 'Segun Daini
Sent: Sunday, October 04, 2009 5:11 AM
To: Kingsley Charles; [email protected]
Subject: Re: [OSL | CCIE_Security] Transparent firewall with trunking

 

Hi,

For transparent firewall, you can only split a single network into two
separate networks bridged by the FW.

The FW interfaces will need to be in unique vlan in a single switch scenario
while for a two switch scenario, the vlan may be same.

The FW int can carry traffic for multiple vlan, thats why you cannot trunk
it. Also in multi context, the interface cant be shared.

Regards.

 

  _____  

From: Kingsley Charles <[email protected]>
To: [email protected]
Sent: Sunday, October 4, 2009 9:47:33 AM
Subject: [OSL | CCIE_Security] Transparent firewall with trunking

Hi all

 

I am trying trunking with transparent firewall with following topology:

 

 

     10.20.30.43
10.20.30.42

R1 (vlan2)-------------I
I-------------------- (vlan2) R3

 
Switch--------Trunking---------ASA---------Trunking---------- Switch 

R2 (vlan3)-------------I
I  ------------------- (vlan3) R4

     20.10.30.43
20.10.30.42

 

 

I have four routers. 

 

R1 and R2 are connected to switch 1 in vlan 2 and vlan 3 respectively.

R3 and R4 are connected to switch 1 in vlan 2 and vlan 3 respectively.

 

ASA G0/1 is connected to switch 1 with trunking.

ASA G0/0 is connected to switch 2 with trunking.

 

 

vlan 2 - 10.20.30.0

vlan 3 - 20.10.30.0

 

 

Based on my investigation, it seems we can't achieve this. During the
initial config itself, I am facing an issue. If I associate vlan2 to e1.2,
then I am not able to associate to 

vlan2 to e0.2 again.

 

 

interface Ethernet1
 no nameif
 no security-level
!
interface Ethernet1.2
 vlan 2
 nameif vlan2
 security-level 100
!
interface Ethernet1.3
 vlan 3
 nameif vlan3
 security-level 100

 

pixfirewall(config-subif)# vlan2
ERROR: VLAN 2 has been assigned to another interface

 

pixfirewall(config-subif)# vlan3
ERROR: VLAN 3 has been assigned to another interface

 

 

 

I am not able configure transparent firewall across vlans but how we do, if
there a case, if I need transparent firewall across trunk that carries many
vlans. Is it possible with ASA transparent firewall?

 

 

With regards

Kings

 

 

 

 

 

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