Hello,

I've a problem that sometimes the network response to the internet is slow. When I connect directly to the modem no problems but when the data travels throw the internal network its much slower. Normal internet pages have no problem, but we are using a program/website that have to load PDF pages. This is much slower when it have to travel throw our network and after time its become slower and slower.

Now I have installed an Rapsberry Pi with the QoS monitoring and the RTT is around 20ms. The network is as follows. ISP modem vlan1>switch1>switch2>switch3>switch4>vlan1 Firewall/Fortigate vlan2 >switch4>switch3>switch2>switch1>workstation.

ISP wan adres is travel over vlan 1 to the fortigate firewall and then travels back over vlan 2 to the client. The raspberry Pi is also connected to switch 1 and PRTG is on switch 4 both in the same vlan.

Article Comments

My Question is how can I locate the problem. Now I'm measuring a RTT of 20ms is that normal for a local network?


Dec, 2017 - Permalink

Hi there,

Unfortunately, we can't really troubleshoot this as this is more a job for a network professional which analyzes the network more extensively and most likely knows where the physical bottlenecks are. According to some research, these are typical timings for local RTT-Values:

  • 100BASE-TX-Ethernet <1 ms
  • WLAN 802.11b 10 ms
  • Generic Cable 10 ms
  • ADSL 6000 ohne Fastpath 40 ms
  • ADSL 2000 ohne Fastpath 55 ms
  • ISDN 200 ms
  • UMTS 300–400 ms
  • GPRS 700-1000 ms

(Source: https://de.wikipedia.org/wiki/Paketumlaufzeit)

Best regards.


Dec, 2017 - Permalink

Thank you for the response!


Dec, 2017 - Permalink