SE Articles From the Field
Summary
In Stratusphere UX, administrators may observe RDP or RFX session latency consistently reported around ~400 ms. This behavior is not indicative of actual network latency and is most commonly observed when RDP is using UDP transport (RDPEUDP).
Symptoms
- Protocol shows RDP or RFX
- Session Latency displays ~350–450 ms (commonly 400.00 ms)
- Latency appears static or minimally changing
- Session Quality = 100%
- Packet Loss = 0%
- User experience is normal
Example
The screenshot below illustrates this behavior:
- Latency values shown in RED (~400 ms) indicate sessions using UDP transport
- Latency values shown in GREEN (low ms values) indicate sessions using TCP-only transport (UDP disabled)
Cause
Modern Microsoft RDP (RDP 8.0+) uses a dual transport model:
- TCP: session establishment and control
- UDP (RDPEUDP): preferred for graphics and input
Both RDP and RFX sessions can leverage UDP.
Why 400 ms Appears
When UDP is in use:
- No traditional RTT measurement
- Latency becomes synthetic or stale
- Often defaults around ~400 ms
Impact in Stratusphere UX
- Reported latency does not reflect actual network latency
- Other metrics remain accurate (Quality, Packet Loss)
Resolution / Guidance
Expected behavior if:
- Protocol = RDP or RFX
- Latency ≈ 400 ms
- No packet loss
- Good user experience
Validation Steps
1. Disable UDP via GPO:
Turn Off UDP On Client = Enabled
2. Check client:
netstat -an | findstr 3389
Best Practices
- Do not treat 400 ms as a network issue
- Correlate with user experience and packet loss
Key Takeaway
A latency value around 400 ms typically indicates UDP transport is in use and not actual latency.