Connection Cache add failed

Ninad94

Hi Team,

Greetings!

We are having MPLS connectivity between branch and HO firewall. We are trying to access out finsso application which is hosted behind HO firewall over the MPLS connectivity. But that application is not accessible and if I see in packet capture I am getting "Drop Code: 254(Connection Cache Add Failed), Module Id: 25(network), (Ref.Id: _3450_uyHtJcpfngKrRmv) 1:1".

Please find below screenshot of packet capture.

@Saravanan @shiprasahu93 @Poorni_5 @Nevyaditha @Vigneshkumar_S

shiprasahu93

Hello @Ninad94,

Based on the screenshot, I see that the IP: 192.168.4.17 is sending a RST+ACK and most probably the subsequent packet might be getting dropped on the firewall. Since SonicWall is a stateful firewall, it makes a note of the TCP connection status. After a RST, the TCP connection is interrupted due to which you are seeing that drop on the firewall.

It looks like the drop is expected based on the packet capture, please take a look at the IP: 192.168.4.17. That is the IP, terminating this connection.

This KB gives more info on that drop code.

https://www.sonicwall.com/support/knowledge-base/packet-capture-shows-packet-dropped-connection-cache-add-failed/170505672579353/#:~:text=Packet%20Capture%20shows%3A%20Packet%20dropped%20%2D%20Connection%20Cache%20Add%20Failed,-12%2F20%2F2019&text=CAUSE%3A,packets%2C%20it%20closes%20the%20socket.

Thanks!

Ninad94

Hi @shiprasahu93

I have tried on Multiple client machines by accessing application but every Time I am getting same type of packet capture.

Should I try by enabling " fix/ignore TCP malformed packets" on diag page.

Is this setting help me to resolve this issue because if you see in Packet capture we recieve out of order TCP packets from Sever end.

shiprasahu93

Yes, you can certainly try that. Please verify the MTU across the MPLS connection, that might be causing such issues too.

Thanks!