Dropped packets - how many is normal?

notty · October 19

So I recently started playing with netdata. Turns out one of my KVM servers is dropping a lot of incoming packets - consistently around 50-60 each second.

The server is basically idle. I can see the dropped count increasing with watch ifconfig ens3 looking under RX/dropped.

I did try exploring with tcpdump: it shows lots of ARP and "ICMP6 neighbor solicitation" packets. The server has IPv6 disabled at the kernel, so I guess I should expect a few dropped packets from that, but 60/second seemed surprising!

deank · October 19

Let your host know.
Then cancel your plans with them OR chargeback.
Then sue for mental damage.

edfox · October 19

0

Jord · October 19

Das nicht gut

LTniger · October 19

None, null, nill, zero. Packets must be delivered no matter what.

Clouvider · October 19

If you can see them in your OS that means they are dropped by your kernel.

jar · October 19

I hate this meme but it’s too perfect for the thread: https://cloud.donnell.online/index.php/s/YDJokepoiWJ8cmM

(Yes I only based this on the thread title)

rm_ · October 19

notty said: The server is basically idle. I can see the dropped count increasing with watch ifconfig ens3 looking under RX/dropped.

This means nothing. Packets can be dropped for various reasons, including due to being not addressed to your host (or to any multicast group it's a member of, or as you noticed, if you have IPv6 disabled). Run a long ping or mtr to measure if you have any actual packet loss.

Janevski · October 19

Do a tcp speed test.

You won't be able to achieve the advertised high speeds if there's even a slight loss.

notty · October 21

Thanks for the advice and Dr Who memes.

So I ran a couple of long tests with ping 8.8.8.8 and actually there was a small amount of packet loss (around 1%) but I'm not sure if that's relevant.

It looks like the 60 packets being dropped per second are all "ICMP6 neighbor solicitation". The tcpdump logs are full of this sort of thing:

16:09:46.038688 IP6 fe80::xxxx:xxxx:xxxx:xxxx > xxxx:xxxx:xxxx:xxxx:xxxx: ICMP6, neighbor solicitation, who has xxxx:xxxx:xxxx:xxxx:dead:babe:f00d:cafe, length 32

Yes, note the "fun" IPv6 address... not sure what to make of that too... perhaps someone is sending me encoded messages!

ITLabs · October 21

@notty said:
Yes, note the "fun" IPv6 address... not sure what to make of that too... perhaps someone is sending me encoded messages!

That's Hexspeak.

Janevski · October 22

notty said: not sure what to make of that too... perhaps someone is sending me encoded messages!

Have you noticed how they put cabbages inside salads?
Well, that's pretty much the same thing.

notty · October 22

LOL what is this forum I have joined??

So just to ensure I have understood correctly,

IPv4 = Lettuce
IPv6 = Cabbage
I went to the "dead babe f00d" cafe and ordered some salad
But instead of lettuce I ended up getting cabbage
In fact someone started firing 60 cabbages at me every second
But it's ok, because they are multicast cabbages and can be ignored

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Dropped packets - how many is normal?

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