04-14-2012 03:45 AM
Below is the production setup we have
(host)<---------(NS5400)---------------> (ISG 2000) <------------------------> (ISG 1000)<------>(Server)
Host IP = 10.0.228.26 (the host is initaiting traffic towards the server)
Server IP = 10.8.66.129
Correct routing is in place
policy is created on all three firewalls and required ports are permitted.
no natting is invlolved at all
Blow is the traffic log from the NS 5400 (which is first firewall or first hop from the host)
NS5400: NetScreen device_id=NS5400 [Root]system-notification-00257(traffic): start_time="today" duration=66 policy_id=3902 service=icmp proto=1 src zone=xxxxxxx dst zone=yyyyyyy action=Permit sent=82 rcvd=0 src=10.0.228.26 dst=10.8.66.129 icmp type=8 src-xlated ip=10.0.228.26 dst-xlated ip=10.8.66.149 session_id=916791 reason=Close - AGE OUT
04-16-2012 05:37 PM
I would say that these both appear normal so far.
The ISG 2000 is not going to reply to the traffic because the traffic is not destined for this device but the remote server behind yet another firewall. The ISG 2000 is doing all it is suppose to do. This checks to see that the traffic is permitted by a poicy and sets up a session for the traffic then forwards it along. Since this ages out, the issue is upstream.
Either the next firewall, ISG 1000, is dropping the traffic as not permitted. Or has some other configuration that is not compatible with returning the response.
Or the server is not responding for some other reason.
I think you have to get in touch with that remote team and arrange for a flow test and some captures on their side.
Senior IP Engineer - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
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04-16-2012 07:04 PM
Steve, I think the question is, and I am wondering this myself, not so much about the lack of response, but rather about the "Sent=0" at the ISG2000 as opposed to "Sent=82" at the NS5400.
So, by the time the session aged out at the NS5400, it had sent 82 bytes, and received nothing back.
At the ISG2000, however, when the session timed out, the sent counter is still at 0 bytes, thus giving the impression that the ISG2000 never sent any traffic out in the first place.
I have a feeling that something about that counter is a bit off being that the ISG2000 is ASIC-based, but I think so is the NS-5400, so I'm not sure why the difference there.