Strange Ping Statistics

[Joven Bulawit_1]

Hi! Have you ever encountered this before? Ping statistics shows that packet received is greater than the packet transmitted, hence a negative packet loss:

serverA @ root : [/home/root] #ping serverB_nb2
PING serverB_nb2: 64 byte packets
64 bytes from xx.xxx.xxx.xx: icmp_seq=0. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=0. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=0. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=0. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=1. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=2. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=3. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=4. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=5. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=6. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=7. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=8. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=9. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=10. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=11. time=0. ms
64 bytes from xx.xxx.xxx.xx: icmp_seq=12. time=0. ms

----serverB_nb2 PING Statistics----
13 packets transmitted, 16 packets received, -23% packet loss
round-trip (ms) min/avg/max = 0/0/0


Notice that "icmp_seq=0" appeared 4 times and they appeared at the same time. When you ping the server again, the output is normal (packets received=packets transmitted). Please help.....

[Jeeshan]

is this comes very often or u just notice it suddenly?


hmmm, seems not too much worry about this.

[Joven Bulawit_1]

Yes, this comes very often. I just want to know what causes this.

[Laurent Menase]

1) are there multiple way between the 2 systems
2) loops in your network and spanning tree not making it right
3) 4 systems with the same address
4) JAGaf54976 fixes since PHNE_33628 - but this only gives 1 repetition usually

you should take traces at all levels:

1) with nettl at nic layer at both endpoints
( or with tcpdump in raw mode)
2) on the intermediate switches.

[Joven Bulawit_1]

Hi Laurent! Thank you for your reply. Actually serverB is a media server and yes there are multiple ways between the two server. One of them is serverB_nb2 which is a backup LAN.

Will this cause any problem? The ping behaves normally when executed again on the same server and same IP.

[Laurent Menase]

So it is normal, if the address is not yet in switch address table, then it sends the icmp message to all its outputs until the way is identified.

[Laurent Menase]

So it is normal, if the address is not yet in switch address table, then it sends the icmp message to all its outputs until the way is identified.

It is ok as long as you don't use any weak protocols.


- just check that you don't have any misconfiguration between your switch and system too - like an aggregation on a side and no aggregation on the other.

[Joven Bulawit_1]

Hi! how do i add to the switch table?

[Laurent Menase]

depends on your switch,
switch add it automatically with the first message exchanged.