# ping limitation?



## Shura (Sep 10, 2010)

Hi,
Can anyone describe what's happening?


```
shura [/home/shura]$ sudo ping -s 26000 -c 10 10.0.0.10
PING 10.0.0.10 (10.0.0.10): 26000 data bytes

--- 10.0.0.10 ping statistics ---
10 packets transmitted, 0 packets received, 100.0% packet loss

shura [/home/shura]$ sudo ping -s 25000 -c 10 10.0.0.10
PING 10.0.0.10 (10.0.0.10): 25000 data bytes
25008 bytes from 10.0.0.10: icmp_seq=0 ttl=64 time=4.497 ms
25008 bytes from 10.0.0.10: icmp_seq=1 ttl=64 time=4.448 ms
25008 bytes from 10.0.0.10: icmp_seq=2 ttl=64 time=4.522 ms
25008 bytes from 10.0.0.10: icmp_seq=3 ttl=64 time=4.494 ms
25008 bytes from 10.0.0.10: icmp_seq=4 ttl=64 time=4.469 ms
25008 bytes from 10.0.0.10: icmp_seq=5 ttl=64 time=4.543 ms
25008 bytes from 10.0.0.10: icmp_seq=6 ttl=64 time=4.518 ms
25008 bytes from 10.0.0.10: icmp_seq=7 ttl=64 time=4.490 ms
25008 bytes from 10.0.0.10: icmp_seq=8 ttl=64 time=4.464 ms
25008 bytes from 10.0.0.10: icmp_seq=9 ttl=64 time=4.531 ms

--- 10.0.0.10 ping statistics ---
10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 4.448/4.498/4.543/0.029 ms
```

Server does not response on ping packets which biggest around 25000 bytes. Why? I have not found any similar limitation in sysctl.


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## aragon (Sep 10, 2010)

What kind of network are you running?  Standard ethernet packets are limited to 1500 bytes.  With an ICMP packet size of 25000 that means it has to be fragmented 16 times.  An ICMP packet size of 26000 would require 17 fragments.  FreeBSD's default maximum IP fragments per packet seems to be 16:


```
$ sysctl net.inet.ip.maxfragsperpacket
net.inet.ip.maxfragsperpacket: 16
```


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## Shura (Sep 10, 2010)

Thank you, it's helped!


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