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seamlessfirework's avatar
seamlessfirework
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Sep 29, 2023

iRule forwarding to Virtual Server not working

Hey guys, I manage a really old BIG-IP environment. Most of the configuration were not made by myself so I'll try to give you a brief overview what I have here. There is a BIG-IP cluster, some parti...
application delivery
seamlessfirework's avatar
seamlessfirework
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You mean what BIG-IP version I am running? If yes 14.1.5.3.

Paulius's avatar
Paulius
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Sep 29, 2023

seamlessfirework The syntax in the iRule seems to be correct, supported on this code version, and I don't see any bugs relating to this specific action. You might consider running the following tcpdump and opening it up in wireshark to see what the F5 is doing with it.

tcpdump -nni 0.0:nnp host <first_virtual_server_IP> -w /shared/tmp/VS_Tshoot.pcap

This should show you exactly where the traffic is going if you look at the F5 field that will be added into the capture. It might be worth uploading a QKVIEW to iHealth and see if it can find anything as well.

  • seamlessfirework's avatar
    seamlessfirework
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    Sep 29, 2023

    Paulius Thanks for your quick hint. An upload to iHealth is not possible. Sorry. But I did a capture and found something strange to me. The BIG-IP sends a TCP reset because of an iRule execution error. Have a look at the F5 trailer

    F5 Ethernet Trailer Protocol
    F5 Trailer Header - Version: 1
        Magic: 0xf5deb0f5
        Length: 122
        Version: 1
    Low Details
        F5 Trailer Header, Provider: 1, Type: 1
            Provider: 1
            Type: 1
            Trailer length: 44
            Version: 2
        Ingress: False (OUT)
        Slot (1-based): 1
        TMM (0-based): 2
        Virtual Server: /Common/VirtualServer-443
            Length: 32
            Name: /Common/VirtualServer-443
    Medium Details
        F5 Trailer Header, Provider: 1, Type: 2
            Provider: 1
            Type: 2
            Trailer length: 70
            Version: 4
        Flow ID: 0x00004001830ea800
        Peer ID: 0x0000000000000000
        Connflow Flags High Bits: 0x01202080
        Connflow Flags: 0x04808024
        Flow Type: 0x40
        HA Unit: 0x01
        Reserved: 0x00010008
        Priority: 3
        RST cause: [294f5e2:1864] iRule execution error
            Length: 30
            0000 000. = Version: 0 (0x00)
            .... ...0 = Peer: 0
            Value: 0x00000294f5e2
            Line: 1864
            Cause: iRule execution error

    I've never seen that before to be honest.

    • Paulius's avatar
      Paulius
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      Sep 29, 2023

      seamlessfirework Are you seeing any errors generated in the F5 ltm logs for the iRule applied to either of the virtual servers?

      • seamlessfirework's avatar
        seamlessfirework
        Icon for Cirrus rankCirrus
        Sep 30, 2023

        Paulius I had the same thought but there is no error in the log. I opened a support case. I'm curios what they say about this issue.