We are troubleshooting a packet loss issue in our environment. Users are on the outside of the FTD, Servers on the inside. Servers are VMs in ESXi Hyperflex environment (forgive me for poor terminology).
We can reproduce the issue consistently. Host makes a request for data to the SQL server. Connectivity is successful. SQL server starts to send data. Data starts in slow start but eventually increases in size based on the Window scale 8 (multiple is 256). Eventually the flow experiences mulitple TCP re-transmissions and the server eventually RST the connection.
We have not applied any QoS but I see in the show asp drop output a ton of queue tail drops. (I just cleared the counters one week ago.)
Is there a default QoS configuration on FTD that would cause this to be incrimenting?
FTD 4110s with FP code 7.25.
- Server advertises MSS 1460
- Client advertises MSS 1460
- Firepower is still set at default 1380
- All interfaces within Hyperflex, Fabric Interconnect and Upstream switches MTUs are 1500
- FTD interfaces MTUs are 1500
