ASA multiple connections (VLANS) to the same Ethernet

Unanswered Question
Aug 5th, 2009


I have an ASA 5505 (SEC Plus) and I'm trying to configure it so it can be accessed from two subnets running in the same switch. Let's call the subnets: and

I configured a VLAN for on one ethernet port and another VLAN for on another port. Let's assume that the two VLAN interfaces are configured with the following addresses and Both ASA ports are plugged into the same switch using different ports so that hosts from each respective subnet can get to the ASA. When I login to the ASA, I can ping hosts on both subnets via the respective interfaces but when I try to ping from the hosts in that subnet, I get a single reply and the rest of the pings time out:

Pinging with 32 bytes of data:

Reply from bytes=32 time=1ms TTL=255

Request timed out.

Request timed out.

Request timed out.

Ping statistics for

Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),

Approximate round trip times in milli-seconds:

Minimum = 1ms, Maximum = 1ms, Average = 1ms

What am I doing wrong?

Thank you!


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guibarati Fri, 08/07/2009 - 11:52

you are connecting the two ports on the same switch with no Vlan on the swith?

If so that is the problem, you are connecting ASA's interface 1 and ASA's interface 2 to eachother over layer2

They may be sharing the same MAC also.

You need either connect them to different switches or to different VLANS on the same switch.


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