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Low level packet loss on G�ANT2 DK-DE backbone circuit

PTS Case 29


Whilst investigating an unrelated router issue (GEANT2 TT #1047863), low level packet loss (about 0.1%) was detected on the path between the DK and DE MPs (Measurement Points - devices running iperf?BWCTL and HADES OWD monitoring software).

There appears to be a clear correlation between the packet loss seen when running tests from DK to DE, and the packets shown as dropped by Eth0 interface on the DE MP. Whilst the correlation is not 1 to 1, there is nothing to suggest there is packet loss other than on the DE MP itself e.g. UDP BWCTL tests run between DK and AT completed without packet loss, either for iperf or for the AT Ethernet interface. A check on other MPs Ethernet cards shows that several suffer from similar problems - DE drops 0.003%, NL drops 0.01%, HU drops 0.0006%. Given that the NICs are already optimized for bulk transfer, there is nothing to suggest that problems are anything other than the limitations with the NICs themselves, and no further action is required for DE.

– Main.TobyRodwell - 20 Aug 2007

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