Op 20 jun. 2019, om 22:32 heeft Marco van Tol <ma...@tols.org> het volgende
geschreven:
>
> Hi there,
>
> I'm trying to write a patch for collectd to generate trend graphs on ipv4 and
> ipv6 statistics.
>
> I use the sysctls net.inet.ip.stats and net.inet6.ip6.stats for this.
>
> The structs I use to parse these sysctls are "struct ipstat" and "struct
> ip6stat".
>
> While doing this, I keep running into the fact that the "struct
> ipstat.ips_total" count seems to be twice the number of ipv4 packets that
> actually got received on a host. Does this make any sense at all?
>
> So, in other words, if I call "sysctls net.inet.ip.stats", and do another
> call 1 second later, I can deduce a per-second incoming ipv4 packet rate.
> This seems to be twice as high as actually happening.
>
> The number reported in struct ip6stat.ip6s_total seems to be correct.
>
> Is there any reason for the ips_total to be twice the number of ipv4 packets
> that actually got received?
>
> Another way to witness these counts is by doing: netstat -s -p ip, and then
> checkout "total packets received" on a per-second basis.
To briefly come back to this, when I count the components in the output for
"netstat -s -p ip" it adds up to roughly half of total packets received, like
in the following example:
-----< sum for the below proto ip >-----
62,770,301 total packets received
1,451,001 + 25,691,568 + 3,719,636 = 30,862,205
=> Approximately half the total packets received.
-----< cut here >-----
# netstat -s -p ip
ip:
62770301 total packets received
0 bad header checksums
0 with size smaller than minimum
0 with data size < data length
0 with ip length > max ip packet size
0 with header length < data size
0 with data length < header length
0 with bad options
0 with incorrect version number
0 fragments received
0 fragments dropped (dup or out of space)
0 fragments dropped after timeout
0 packets reassembled ok
1451001 packets for this host
0 packets for unknown/unsupported protocol
25691568 packets forwarded (25683102 packets fast forwarded)
3719636 packets not forwardable
0 packets received for unknown multicast group
0 redirects sent
-----< cut here >-----
While on the same host for IPv6:
-----< sum for the below proto ip >-----
5,848,829 total packets received
1,177,571 + 2,489,660 + 1,482,403 = 5,149,634
=> Much closer to total packets received
-----< cut here >-----
# netstat -s -p ip6
ip6:
5848829 total packets received
0 with size smaller than minimum
0 with data size < data length
0 with bad options
0 with incorrect version number
0 fragments received
0 fragments dropped (dup or out of space)
0 fragments dropped after timeout
0 fragments that exceeded limit
0 packets reassembled ok
1177571 packets for this host
2489660 packets forwarded
1482403 packets not forwardable
0 redirects sent
-----< cut here >-----
What am I overlooking? :-)
--
Marco van Tol
_______________________________________________
freebsd-net@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
