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ASA Transparent Mode For Multiple Subnets

thomaswcisco
Level 1
Level 1

I am looking to replace a FortiGate firewall which is currently working in transparent mode handling mutiple subnets with ASA 5515.  Currently, I am testing transparent mode configuration on ASA 5505, and it will not forward any traffic that is not in the same subnet as IP address assigned to BV interface.

For example, the following configuration works.

10.0.0.3/24 (computer) ---> 10.0.0.2/24 (firewall) ---> 10.0.0.1/24 (computer)

However, the following does not work

10.0.0.3/24 (computer) ---> 10.10.0.2/24 (firewall) ---> 10.0.0.1/24 (computer)

I thought that transparent mode is just a bump in the wire, so why does the IP address/subnet assigned to BV interface affects the traffic?  Is the ASA capable of handling other/multiple subnets in transparent mode other than the subnet assigned to BV interface?

By the way, I used to run PIX 515E 7.2(2) transparent mode filtering multiple subnets.  The current ASA 5505 is on 9.0(1).  Is it the limitation on the ASA 5505 model but not on the more powerful ASA model?

Thank you

16 Replies 16

Thanx a lot Jcarvaja...

darshan shetty
Level 1
Level 1

Dear Thomas,

I had faced the same problem in higher version above 9.0. But it works perfectly fine in versions like 8.2 & 8.4 and  same applies for routed mode as well.

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