TCP RTO Clarification



When looking at the TCP Details page for a custom device, what is the specific difference between RTO’s Out and In?

Are RTO’s Out from the device? Meaning, the device sent a packet to a client and the client did not respond multiple times.
Are RTO’s In from the client? Meaning, the client sent a packet to the device and the device did not respond multiple times.

For a custom device, would RTO’s Out be indicative of a local network issue or a remote network issue?


I think it’s easiest if you start thinking of an RTO as a congestion event.

So if you’re looking at a specific device’s outbound metrics, it is displaying events for data that was sent outbound from the current device to its peer. Therefore, an RTO out is saying that a congestion event occurred when the current device was sending data to its peer.

Conversely, inbound metrics are when the current device is receiving data from its peer. So an inbound RTO is a congestion event that occurred when the devices peer was sending it data.

Does this help?