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I am experiencing a strange issue.

I have two devices:

  • (A) Ubuntu 14.04, x64 computer - 192.168.1.42
  • (B) Embedded ARM computer with Ubuntu 14.04 (Odroid XU4) - 192.168.1.60

Tests:

  • A and B are connected through WiFi on the same router
  • Pings from B to A are fast (< 10ms)
  • Pings from A to B are slow (> 100ms)
  • Pings from A to B are fast if B is pinging A at the same time (< 10ms) and goes up again if B stop pinging A (after ~5secs)

How could I debug it? How could I manage to have a lower ping?

alexis@alexis:~/$ ping 192.168.1.60
PING 192.168.1.60 (192.168.1.60) 56(84) bytes of data.
64 bytes from 192.168.1.60: icmp_seq=1 ttl=64 time=128 ms
64 bytes from 192.168.1.60: icmp_seq=2 ttl=64 time=151 ms
64 bytes from 192.168.1.60: icmp_seq=3 ttl=64 time=181 ms
64 bytes from 192.168.1.60: icmp_seq=4 ttl=64 time=199 ms
64 bytes from 192.168.1.60: icmp_seq=5 ttl=64 time=123 ms
64 bytes from 192.168.1.60: icmp_seq=6 ttl=64 time=151 ms
64 bytes from 192.168.1.60: icmp_seq=7 ttl=64 time=186 ms
64 bytes from 192.168.1.60: icmp_seq=8 ttl=64 time=195 ms
64 bytes from 192.168.1.60: icmp_seq=9 ttl=64 time=117 ms <-- Start pinging from B to A
64 bytes from 192.168.1.60: icmp_seq=10 ttl=64 time=6.12 ms
64 bytes from 192.168.1.60: icmp_seq=11 ttl=64 time=5.76 ms
64 bytes from 192.168.1.60: icmp_seq=12 ttl=64 time=6.20 ms
64 bytes from 192.168.1.60: icmp_seq=13 ttl=64 time=10.8 ms
64 bytes from 192.168.1.60: icmp_seq=14 ttl=64 time=5.72 ms
64 bytes from 192.168.1.60: icmp_seq=15 ttl=64 time=9.90 ms
64 bytes from 192.168.1.60: icmp_seq=16 ttl=64 time=7.54 ms <-- Stop pinging from B to A
64 bytes from 192.168.1.60: icmp_seq=17 ttl=64 time=5.96 ms
64 bytes from 192.168.1.60: icmp_seq=18 ttl=64 time=5.80 ms
64 bytes from 192.168.1.60: icmp_seq=19 ttl=64 time=13.6 ms
64 bytes from 192.168.1.60: icmp_seq=20 ttl=64 time=158 ms
64 bytes from 192.168.1.60: icmp_seq=21 ttl=64 time=281 ms
64 bytes from 192.168.1.60: icmp_seq=22 ttl=64 time=202 ms
64 bytes from 192.168.1.60: icmp_seq=23 ttl=64 time=124 ms
64 bytes from 192.168.1.60: icmp_seq=24 ttl=64 time=147 ms
64 bytes from 192.168.1.60: icmp_seq=25 ttl=64 time=171 ms
--- 192.168.1.60 ping statistics ---
25 packets transmitted, 25 received, 0% packet loss, time 24020ms
rtt min/avg/max/mdev = 5.726/103.973/281.720/84.831 ms
  • May it be an ARP problem. The A computer seems to forget the MAC of B. – Arrow Aug 2 '17 at 18:35
  • I will check this with Wireshark tomorrow! – Alexis Paques Aug 2 '17 at 18:38

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