[smokeping-users] Error in packet loss reporting.
Matthew Swainston
njunk at exemail.com.au
Mon Sep 26 04:16:10 MEST 2005
I have been using Smokeping for quite some time with various versions up to
2.0.2, and there is an annoying little bug (or misconfiguration???) that I
have seen in every version I have tried. The issue is that when the first
packet in a polling cycle is dropped, smokeping reports 100% packet loss,
irrespective of how many packets actually get through. This only appears to
happen on the first packet, and if packet loss happens anywhere else the
correct values seem to be reported.
The following debug of a host shows the problem. In this example I simulated
the problem and verified all traffic and responses with tcpdump. The first
output correctly show 0% packer loss, the second output I dropped the first
packet and let everything else through and instead of showing 1% packet loss
it reports 100% packet loss, with the third line showing everything going
through. On the graph this shows as between 4% and 50% for the first
interval and 89% for the next interval before returning to 0% packet loss.
1127463867 U 0 1.5600000000e-03 1.4600000000e-03
1.4700000000e-03 1.4800000000e-03 1.4800000000e-03
1.4800000000e-03 1.4900000000e-03 1.4900000000e-03
1.5000000000e-03 1.5000000000e-031.5000000000e-03
1.5000000000e-03 1.5000000000e-03 1.5000000000e-03
1.5000000000e-03 1.5000000000e-03 1.5100000000e-03
1.5100000000e-03 1.5100000000e-03 1.5100000000e-03
1.5200000000e-03 1.5200000000e-03 1.5200000000e-03
1.5200000000e-03 1.5200000000e-03 1.5200000000e-03
1.5200000000e-031.5200000000e-03 1.5200000000e-03
1.5200000000e-03 1.5300000000e-03 1.5300000000e-03
1.5300000000e-03 1.5300000000e-03 1.5300000000e-03
1.5300000000e-03 1.5300000000e-03 1.5300000000e-03
1.5300000000e-03 1.5300000000e-03 1.5400000000e-03
1.5400000000e-03 1.5400000000e-03
1.5400000000e-031.5400000000e-03 1.5500000000e-03
1.5500000000e-03 1.5500000000e-03 1.5500000000e-03
1.5600000000e-03 1.5600000000e-03 1.5600000000e-03
1.5600000000e-03 1.5600000000e-03 1.5600000000e-03
1.5700000000e-03 1.5800000000e-03 1.5800000000e-03
1.5800000000e-03 1.6100000000e-03
1.6400000000e-031.6800000000e-03 1.6800000000e-03
1.6900000000e-03 1.7100000000e-03 1.7100000000e-03
1.7100000000e-03 1.7200000000e-03 1.7300000000e-03
1.7800000000e-03 1.8700000000e-03 1.9200000000e-03
2.1300000000e-03 2.7800000000e-03 3.4700000000e-03
3.4900000000e-03 3.5300000000e-03
3.6300000000e-033.6500000000e-03 3.7800000000e-03
3.9900000000e-03 4.2300000000e-03 4.6700000000e-03
5.0200000000e-03 5.6000000000e-03 9.9200000000e-03
1.1880000000e-02 1.2290000000e-02 1.9180000000e-02
2.5110000000e-02 2.5230000000e-02 2.5460000000e-02
2.5950000000e-02 2.6880000000e-02
3.3530000000e-023.4710000000e-02 3.5990000000e-02
3.7290000000e-02 3.9200000000e-02 3.9940000000e-02
4.7420000000e-02
1127464167 U 100 U U U U U U
U U U U U U UU U U U
U U U U U U U U U U
U U UU U U U U U U U
U U U U U U U U UU U
U U U U U U U U U U
U U U U UU U U U U U
U U U U U U U U U U
UU U U U U U U U U U
U U U U U U UU U U
1127464467 U 0 1.6000000000e-03 1.4400000000e-03
1.4400000000e-03 1.4400000000e-03 1.4500000000e-03
1.4500000000e-03 1.4500000000e-03 1.4500000000e-03
1.4500000000e-03 1.4500000000e-031.4500000000e-03
1.4500000000e-03 1.4600000000e-03 1.4600000000e-03
1.4700000000e-03 1.4700000000e-03 1.4700000000e-03
1.4700000000e-03 1.4700000000e-03 1.4800000000e-03
1.4800000000e-03 1.4800000000e-03 1.4800000000e-03
1.4900000000e-03 1.4900000000e-03 1.4900000000e-03
1.4900000000e-031.4900000000e-03 1.5000000000e-03
1.5000000000e-03 1.5000000000e-03 1.5000000000e-03
1.5000000000e-03 1.5100000000e-03 1.5100000000e-03
1.5200000000e-03 1.5200000000e-03 1.5200000000e-03
1.5200000000e-03 1.5300000000e-03 1.5300000000e-03
1.5400000000e-03 1.5400000000e-03
1.5400000000e-031.5500000000e-03 1.5500000000e-03
1.5500000000e-03 1.5700000000e-03 1.5700000000e-03
1.6000000000e-03 1.6000000000e-03 1.6000000000e-03
1.6000000000e-03 1.6400000000e-03 1.6700000000e-03
1.6700000000e-03 1.6700000000e-03 1.6800000000e-03
1.6800000000e-03 1.6800000000e-03
1.6800000000e-031.7600000000e-03 2.0700000000e-03
2.3500000000e-03 2.5200000000e-03 2.5900000000e-03
2.6900000000e-03 2.8500000000e-03 2.9400000000e-03
3.0500000000e-03 3.2000000000e-03 3.2600000000e-03
3.2900000000e-03 3.3400000000e-03 3.3500000000e-03
3.6200000000e-03 3.6300000000e-03
4.0600000000e-036.6400000000e-03 6.9200000000e-03
8.9600000000e-03 9.3200000000e-03 9.7900000000e-03
1.0020000000e-02 1.5100000000e-02 1.9860000000e-02
2.0690000000e-02 2.5270000000e-02 2.6190000000e-02
2.6280000000e-02 3.0160000000e-02 3.0300000000e-02
3.3640000000e-02 3.4740000000e-02
3.8500000000e-023.9650000000e-02 4.0240000000e-02
4.0520000000e-02 4.3920000000e-02 4.6180000000e-02
4.6980000000e-02
This problem only seems to occur if the first packet is dropped. Apart from
that everything else appears to work perfectly and correctly report packet
loss. Have I got something misconfigured or is this some sort of bug.
Thanks in advance for all suggestions received.
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