Intel Pro/1000 MT and strange ping RTTs
I'm currently running Debian sarge with the e1000 driver on a few
servers. I'm seeing variable round trip times when I send pings to any
host from a host with the Intel Pro/1000 MT. Meaning, I don't have to
ping between these hosts to get the variable RTTs. Comparitively, on
two other servers which are also running sarge, I have extremely
consistent RTTs. The RTTs are all sub millisecond, but it concerns me
that there is a fluctuation here. My guess is that it's either related
to the Intel Pro/1000 hardware or the device drivers. Does anyone have
any clues on this? Incidentally, I've swapped out the switch and
tested it with the consistent ping time servers - it's not the switch.
Oh, and all hosts are on the same switch.
Ping capture below:
64 bytes from 172.20.1.11: icmp_seq=1 ttl=64 time=0.153 ms
64 bytes from 172.20.1.11: icmp_seq=2 ttl=64 time=0.325 ms
64 bytes from 172.20.1.11: icmp_seq=3 ttl=64 time=0.249 ms
64 bytes from 172.20.1.11: icmp_seq=4 ttl=64 time=0.173 ms
64 bytes from 172.20.1.11: icmp_seq=5 ttl=64 time=0.219 ms
64 bytes from 172.20.1.11: icmp_seq=6 ttl=64 time=0.142 ms
64 bytes from 172.20.1.11: icmp_seq=7 ttl=64 time=0.189 ms
64 bytes from 172.20.1.11: icmp_seq=8 ttl=64 time=0.111 ms
64 bytes from 172.20.1.11: icmp_seq=9 ttl=64 time=0.282 ms
64 bytes from 172.20.1.11: icmp_seq=10 ttl=64 time=0.204 ms
64 bytes from 172.20.1.11: icmp_seq=11 ttl=64 time=0.251 ms
64 bytes from 172.20.1.11: icmp_seq=12 ttl=64 time=0.175 ms
64 bytes from 172.20.1.11: icmp_seq=13 ttl=64 time=0.221 ms
64 bytes from 172.20.1.11: icmp_seq=14 ttl=64 time=0.144 ms
64 bytes from 172.20.1.11: icmp_seq=15 ttl=64 time=0.192 ms
64 bytes from 172.20.1.11: icmp_seq=16 ttl=64 time=0.237 ms
64 bytes from 172.20.1.11: icmp_seq=17 ttl=64 time=0.284 ms
64 bytes from 172.20.1.11: icmp_seq=18 ttl=64 time=0.207 ms
64 bytes from 172.20.1.11: icmp_seq=19 ttl=64 time=0.253 ms
64 bytes from 172.20.1.11: icmp_seq=20 ttl=64 time=0.178 ms
Compared to non-Intel card servers:
64 bytes from 192.168.1.110: icmp_seq=1 ttl=64 time=0.164 ms
64 bytes from 192.168.1.110: icmp_seq=2 ttl=64 time=0.169 ms
64 bytes from 192.168.1.110: icmp_seq=3 ttl=64 time=0.165 ms
64 bytes from 192.168.1.110: icmp_seq=4 ttl=64 time=0.167 ms
64 bytes from 192.168.1.110: icmp_seq=5 ttl=64 time=0.172 ms
64 bytes from 192.168.1.110: icmp_seq=6 ttl=64 time=0.166 ms
64 bytes from 192.168.1.110: icmp_seq=7 ttl=64 time=0.166 ms
64 bytes from 192.168.1.110: icmp_seq=8 ttl=64 time=0.167 ms
64 bytes from 192.168.1.110: icmp_seq=9 ttl=64 time=0.168 ms
64 bytes from 192.168.1.110: icmp_seq=10 ttl=64 time=0.166 ms
64 bytes from 192.168.1.110: icmp_seq=11 ttl=64 time=0.165 ms
64 bytes from 192.168.1.110: icmp_seq=12 ttl=64 time=0.163 ms
Thanks,
Mark
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