While trying to analyze a different wifi performance problem I built a really small lab consisting of a Aruba 2530-25G-PoE switch, a single IAP-315 (Central managed).
Connected to the switch I have Miktotik Firewall that runs the DHCP server, and a Linux Desktop.
I then connect a Laptop to the wireless 802.1ac PSK network (5GHz) that broadcasts my local network on the IAP-315.
I've configured:
Band Steering Mode: Prefer 5 GHz
Airtime Fairness Mode: Fair Access
ClientMatch: On
80 MHz Support: Off
Background Spectrum Monitoring: On (Both 2,4GHz and 5 GHz)
Everything works fine I get good throughput with iperf between my laptop and desktop. But what I really can't understand is:
If I ping from the Laptop to the Desktop, I get stready replies around 2-3 ms (as expected).
However, if I ping from my Desktop to the Laptop I get much higher and variating rtt:
64 bytes from 192.168.88.82: icmp_req=1316 ttl=64 time=21.5 ms
64 bytes from 192.168.88.82: icmp_req=1317 ttl=64 time=52.0 ms
64 bytes from 192.168.88.82: icmp_req=1318 ttl=64 time=82.1 ms
64 bytes from 192.168.88.82: icmp_req=1319 ttl=64 time=111 ms
64 bytes from 192.168.88.82: icmp_req=1320 ttl=64 time=37.6 ms
64 bytes from 192.168.88.82: icmp_req=1321 ttl=64 time=68.4 ms
64 bytes from 192.168.88.82: icmp_req=1322 ttl=64 time=97.3 ms
64 bytes from 192.168.88.82: icmp_req=1323 ttl=64 time=24.4 ms
64 bytes from 192.168.88.82: icmp_req=1324 ttl=64 time=53.7 ms
64 bytes from 192.168.88.82: icmp_req=1325 ttl=64 time=82.3 ms
64 bytes from 192.168.88.82: icmp_req=1326 ttl=64 time=111 ms
64 bytes from 192.168.88.82: icmp_req=1327 ttl=64 time=38.2 ms
64 bytes from 192.168.88.82: icmp_req=1328 ttl=64 time=68.3 ms
64 bytes from 192.168.88.82: icmp_req=1329 ttl=64 time=304 ms
64 bytes from 192.168.88.82: icmp_req=1330 ttl=64 time=332 ms
Can anyone explain why I get higher latency pinging in one direction than the other between the exact same two devices?
I've tested with a few different laptops, and also testing pinging from the switch and still see the same behavior. I also saw the exact same behavior in a customers network with a similar setup.
IAP-315 is running 6.5.0.0-4.3.0.0_56428. In my customers network I tried upgrading their IAP to 6.5.1.0-4.3.1.1_57902. Still the same behavior.