Omnitik + SXT = high latency. Why?

RouterOS Wireless Networking
1

Hi!

We have an Omnitik and it have 30 active clients (SXT all of them).
The problem, so i try to ping the clients the reply time is 15-80ms irrespectively of traffic. If I’m pinging the omni, the reply is 1-5ms.
Topology: PPP Concentrator – PtP link (WDS) – Omni --Clients.

Any idea?

2
  • replace wds by station-bridge.
  • use nv2 protocol
  • ensure no wireless signal is below -75dB
  • look for a channel that is free of interference
3

My ptp link is UBNT, but I use wds mode many links and them works correctly.
I’m using nv2 protocol, and wireless mode 5G only N
The worst signal is -75db
The channel is totally free.

192.168.80.1 is the PPP Concentrator & Gateway (GW)
192.168.80.2 Ubnt 1
192.168.80.3 Ubnt 2
192.168.80.6 Omnitik

I’m using vlans from GW to AP-s

If I ping from 192.168.80.1 to 192.168.80.6 the reply time is perfect.
If I ping from 192.168.80.1 to pppoe clients the reply time is bad…

I have many other AP’s without problem, but them running in 5GHz A mode or Ubnt AP’s in N mode

4

i have same issue,pinging from sxt to omnitik i get average of 4 ms with fluctions going up to about 18ms,10ms, etc.

Omnitik
Ap-Bridge
NV2 enabled
AP and Client adaptive noise immunity enabled
noise floor of -119dbm
tried nstreme on/off
tried 20mhz and 20/40 above/below

SXT
Station-bridge
NV2 enabled
AMPDU Priorities on/off

5

Are the ping responses consistent?

I have noticed this with other high power CPE, the first few pings are high, the CPE take a second or two to ramp up the connection speed and tx power.

I don’t know if this is the case with the SXT, but it happens quite often with a Crossroads. Ping isn’t so good on the Dude, but as soon as I start checking into it the ping is under 5ms.

6

i have always had high pings with nv2. and after trying lot have not found a solution
i have a ptp link 4 km groove on one side 711-5hn on the other with 23 dbi grids. 20/40 mhz, 5ghz a/n signal is -70/71 bwtest shows 35-40 mbps but still ping replies vary from 1 ms to 40 ms even at no load. i dunno what to do. so far the customers are not complaining.

7

I can’t say for NV2, but nstreme latency was fairly erratic until the link had a decent amount of traffic going across it. When it was me and 20 other people, ping google would show 10ms, 70ms, 20ms, 50ms, 20ms, 20ms, 40ms, etc. Now that there is a never ending run of data across that link my ping is fairly consistent between 10-20 ms.

8

Same here. In a PtP link with 2 SXT (50m, power set at 0dbm, LOS):

  • Nv2: 10ms minimum (oscilating up to 50ms)
  • 802.11: 1-2ms

In Omnitik + SXT: the same

802.11: lower perfomance. 1-2ms ping
nv2: higher perfomance (about 75% more throughput). 12-18ms ping

Regards

9

Because of the way media access works with the NV2 protocol, you will see higher pings on an unloaded link / set of links.

Pass some traffic, say 5-10 megabit and you will most likely notice ping times drop to a few Ms. I believe it is in part due to the polling, and the TDMA access scheme designed into the protocol.

Also check your NV2 TDMA Period Size. Usually 2-4 ms works well for me with Nv2 most of the time.