A new Expert Event has been added to track the full length of a TCP Handshake from the first SYN sent from the client to the ACK that closes off the three-way handshake. This Expert Events provides a value that better represents the network latency from a user’s perspective.
LiveWire:
| Expert Event | Notes | |
|---|---|---|
| 1 | TCP Slow Connection Setup | Description: The TCP handshake appears to be slow based
on the configured threshold.This expert measures from the
first SYN packet that the client sends, ratherthan the
last SYN packet. This gives a more realistic value from
the perspective ofthe client attempting a
connection. Cause: There is network latency or the endpoints are slow to process the handshake. Remedy: Check round-trip packet delay (latency). Check the CPU utilization of thereceiver. Check the responsiveness of the receiver by capturing at the receivingend of the data. |
A new expert called TCP Slow Connection Setup has been added to LiveWire, as well as a new engine expert column called TCP Connection Setup (sec).
LiveFlow:
On the LiveFlow side: There is a new AVC field called artConnectionSetupTimeSum.
LiveFlow Configuration
LiveFlow has two flow timeout values set in liveflow.json that affect this field. By default, the tcp_handshake_timeout is 2 seconds, and the tcp_wait_timeout is 3 seconds - these values are set for optimization purposes. The customer may configure the values to a maximum of 30 seconds to suit their needs, otherwise the long tcp handshake will be split into multiple flows.