network problems in local network (wired)

awerthmann · 10-22-2015, 04:41 AM

Hello,
I have a network problem in LAN.
IP of the router is 10.0.2.1 (Linux Ubuntu).
(ifconfig:

Code:

eth0      Link encap:Ethernet  HWaddr 90:e2:ba:98:9c:2b  
          inet addr:10.0.2.1  Bcast:10.0.2.255  Mask:255.255.255.0
          inet6 addr: fe80::92e2:baff:fe98:9c2b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:16302086 errors:4 dropped:0 overruns:0 frame:2
          TX packets:17489404 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:13964006780 (13.9 GB)  TX bytes:16493383298 (16.4 GB)

If I ping a wired local machine from the router i get:

Code:

PING 10.0.2.2 (10.0.2.2) 56(84) bytes of data.
64 bytes from 10.0.2.2: icmp_seq=1 ttl=64 time=41.3 ms
64 bytes from 10.0.2.2: icmp_seq=2 ttl=64 time=37.4 ms
64 bytes from 10.0.2.2: icmp_seq=3 ttl=64 time=35.9 ms
64 bytes from 10.0.2.2: icmp_seq=4 ttl=64 time=34.9 ms
64 bytes from 10.0.2.2: icmp_seq=5 ttl=64 time=33.9 ms
64 bytes from 10.0.2.2: icmp_seq=6 ttl=64 time=32.8 ms
64 bytes from 10.0.2.2: icmp_seq=7 ttl=64 time=31.0 ms
64 bytes from 10.0.2.2: icmp_seq=8 ttl=64 time=29.8 ms
64 bytes from 10.0.2.2: icmp_seq=9 ttl=64 time=27.9 ms
64 bytes from 10.0.2.2: icmp_seq=10 ttl=64 time=26.9 ms
64 bytes from 10.0.2.2: icmp_seq=11 ttl=64 time=25.9 ms
64 bytes from 10.0.2.2: icmp_seq=12 ttl=64 time=24.9 ms
64 bytes from 10.0.2.2: icmp_seq=13 ttl=64 time=26.7 ms
64 bytes from 10.0.2.2: icmp_seq=14 ttl=64 time=22.1 ms
64 bytes from 10.0.2.2: icmp_seq=15 ttl=64 time=20.9 ms
64 bytes from 10.0.2.2: icmp_seq=16 ttl=64 time=18.9 ms
64 bytes from 10.0.2.2: icmp_seq=17 ttl=64 time=17.9 ms
64 bytes from 10.0.2.2: icmp_seq=18 ttl=64 time=15.9 ms
64 bytes from 10.0.2.2: icmp_seq=19 ttl=64 time=14.8 ms
64 bytes from 10.0.2.2: icmp_seq=20 ttl=64 time=12.9 ms
64 bytes from 10.0.2.2: icmp_seq=21 ttl=64 time=11.9 ms
64 bytes from 10.0.2.2: icmp_seq=22 ttl=64 time=12.4 ms
64 bytes from 10.0.2.2: icmp_seq=23 ttl=64 time=11.0 ms
64 bytes from 10.0.2.2: icmp_seq=24 ttl=64 time=9.80 ms
64 bytes from 10.0.2.2: icmp_seq=25 ttl=64 time=7.97 ms
64 bytes from 10.0.2.2: icmp_seq=26 ttl=64 time=6.90 ms
64 bytes from 10.0.2.2: icmp_seq=27 ttl=64 time=4.92 ms
64 bytes from 10.0.2.2: icmp_seq=28 ttl=64 time=2.92 ms
64 bytes from 10.0.2.2: icmp_seq=29 ttl=64 time=98.4 ms
64 bytes from 10.0.2.2: icmp_seq=30 ttl=64 time=97.5 ms
64 bytes from 10.0.2.2: icmp_seq=31 ttl=64 time=98.4 ms
64 bytes from 10.0.2.2: icmp_seq=32 ttl=64 time=94.2 ms
64 bytes from 10.0.2.2: icmp_seq=33 ttl=64 time=93.0 ms
64 bytes from 10.0.2.2: icmp_seq=34 ttl=64 time=92.0 ms
64 bytes from 10.0.2.2: icmp_seq=35 ttl=64 time=90.9 ms
64 bytes from 10.0.2.2: icmp_seq=36 ttl=64 time=90.0 ms
64 bytes from 10.0.2.2: icmp_seq=37 ttl=64 time=89.0 ms
64 bytes from 10.0.2.2: icmp_seq=38 ttl=64 time=88.0 ms
64 bytes from 10.0.2.2: icmp_seq=39 ttl=64 time=87.0 ms
64 bytes from 10.0.2.2: icmp_seq=40 ttl=64 time=86.0 ms
64 bytes from 10.0.2.2: icmp_seq=41 ttl=64 time=84.9 ms
64 bytes from 10.0.2.2: icmp_seq=42 ttl=64 time=83.9 ms
64 bytes from 10.0.2.2: icmp_seq=43 ttl=64 time=83.0 ms
64 bytes from 10.0.2.2: icmp_seq=44 ttl=64 time=82.0 ms
64 bytes from 10.0.2.2: icmp_seq=45 ttl=64 time=83.5 ms
64 bytes from 10.0.2.2: icmp_seq=46 ttl=64 time=79.5 ms
64 bytes from 10.0.2.2: icmp_seq=47 ttl=64 time=78.0 ms
64 bytes from 10.0.2.2: icmp_seq=48 ttl=64 time=76.9 ms
64 bytes from 10.0.2.2: icmp_seq=49 ttl=64 time=75.0 ms
64 bytes from 10.0.2.2: icmp_seq=50 ttl=64 time=74.0 ms
64 bytes from 10.0.2.2: icmp_seq=51 ttl=64 time=72.9 ms
64 bytes from 10.0.2.2: icmp_seq=52 ttl=64 time=71.0 ms
64 bytes from 10.0.2.2: icmp_seq=53 ttl=64 time=72.5 ms
64 bytes from 10.0.2.2: icmp_seq=54 ttl=64 time=70.8 ms
64 bytes from 10.0.2.2: icmp_seq=55 ttl=64 time=66.4 ms
64 bytes from 10.0.2.2: icmp_seq=56 ttl=64 time=64.9 ms
64 bytes from 10.0.2.2: icmp_seq=57 ttl=64 time=65.5 ms
64 bytes from 10.0.2.2: icmp_seq=58 ttl=64 time=63.8 ms
64 bytes from 10.0.2.2: icmp_seq=59 ttl=64 time=60.0 ms
64 bytes from 10.0.2.2: icmp_seq=60 ttl=64 time=58.9 ms
64 bytes from 10.0.2.2: icmp_seq=61 ttl=64 time=57.9 ms
64 bytes from 10.0.2.2: icmp_seq=62 ttl=64 time=56.9 ms
64 bytes from 10.0.2.2: icmp_seq=63 ttl=64 time=58.4 ms
64 bytes from 10.0.2.2: icmp_seq=64 ttl=64 time=54.4 ms
64 bytes from 10.0.2.2: icmp_seq=65 ttl=64 time=53.0 ms
64 bytes from 10.0.2.2: icmp_seq=66 ttl=64 time=51.8 ms
64 bytes from 10.0.2.2: icmp_seq=67 ttl=64 time=50.0 ms
64 bytes from 10.0.2.2: icmp_seq=68 ttl=64 time=48.8 ms
64 bytes from 10.0.2.2: icmp_seq=69 ttl=64 time=46.9 ms
64 bytes from 10.0.2.2: icmp_seq=70 ttl=64 time=45.9 ms
64 bytes from 10.0.2.2: icmp_seq=71 ttl=64 time=43.9 ms
64 bytes from 10.0.2.2: icmp_seq=72 ttl=64 time=42.9 ms
64 bytes from 10.0.2.2: icmp_seq=73 ttl=64 time=41.9 ms
64 bytes from 10.0.2.2: icmp_seq=74 ttl=64 time=40.9 ms
64 bytes from 10.0.2.2: icmp_seq=75 ttl=64 time=42.4 ms
64 bytes from 10.0.2.2: icmp_seq=76 ttl=64 time=38.4 ms
64 bytes from 10.0.2.2: icmp_seq=77 ttl=64 time=36.9 ms
64 bytes from 10.0.2.2: icmp_seq=78 ttl=64 time=35.9 ms
64 bytes from 10.0.2.2: icmp_seq=79 ttl=64 time=34.7 ms
64 bytes from 10.0.2.2: icmp_seq=80 ttl=64 time=32.9 ms
64 bytes from 10.0.2.2: icmp_seq=81 ttl=64 time=31.9 ms
64 bytes from 10.0.2.2: icmp_seq=82 ttl=64 time=30.9 ms
64 bytes from 10.0.2.2: icmp_seq=83 ttl=64 time=30.0 ms
64 bytes from 10.0.2.2: icmp_seq=84 ttl=64 time=31.4 ms
64 bytes from 10.0.2.2: icmp_seq=85 ttl=64 time=27.4 ms
64 bytes from 10.0.2.2: icmp_seq=86 ttl=64 time=25.8 ms
64 bytes from 10.0.2.2: icmp_seq=87 ttl=64 time=23.9 ms
64 bytes from 10.0.2.2: icmp_seq=88 ttl=64 time=22.8 ms
64 bytes from 10.0.2.2: icmp_seq=89 ttl=64 time=20.9 ms
64 bytes from 10.0.2.2: icmp_seq=90 ttl=64 time=20.1 ms
64 bytes from 10.0.2.2: icmp_seq=91 ttl=64 time=18.8 ms
64 bytes from 10.0.2.2: icmp_seq=92 ttl=64 time=16.9 ms
64 bytes from 10.0.2.2: icmp_seq=93 ttl=64 time=17.4 ms
64 bytes from 10.0.2.2: icmp_seq=94 ttl=64 time=15.5 ms
64 bytes from 10.0.2.2: icmp_seq=95 ttl=64 time=11.6 ms
64 bytes from 10.0.2.2: icmp_seq=96 ttl=64 time=12.4 ms
64 bytes from 10.0.2.2: icmp_seq=97 ttl=64 time=10.8 ms
64 bytes from 10.0.2.2: icmp_seq=98 ttl=64 time=8.94 ms

As you see there is no packet loss. But the ping latency is way too high (should by < 1ms) and it changes
slowly from 100 ms down to 2 ms and then jumps back to 100 ms .. and it repeats that way.
What can cause this ?

The network switch behind the Router is a new one.
Ping times from a machine to an other machine connected to the switch is alway < 1ms.
Pinging the router gives the high inconistently ping times above.

Please help.

nini09 · 10-22-2015, 02:31 PM

If local machine ping router, what's ping latency? Not router ping local machine.

awerthmann · 10-23-2015, 05:48 AM

If a local machine pings the router its the same.

I have found out there are irq handling issues. The mainboard has an asmedia pci bridge and there is some bug in it.
Sometimes the irq 18 gets disabled by the kernel, then there are these latency and throughput issues.
(The network card is a PCI card.)

After rebooting the machine the latency is good but only for some minutes / hours (depending on network traffic).

Actually I'm trying the kernel boot option "irqpoll". The latency is now good since twelve hours (fingers crossed).