topic Re: ping response time in Operating System - HP-UX

ping response time

Roberto Volsa — Wed, 28 Sep 2005 10:04:02 GMT

Hello,
i'm collecting statistics on response time between two HPUX server using ping.

After ping is running for a lot of seconds, i stop the command and get the min/avg/max response time. But the avg has been notified negative!!!

Which is the algoritm used by ping in order to give the avg result?
Based on this algoritm, a slow network can imply a negative avg result?

Thanks in advance
RV

Re: ping response time

Patrick Wallek — Wed, 28 Sep 2005 10:06:45 GMT

I'm not sure how an average can be negative.

Can you please post an example of what you are talking about?

Re: ping response time

A. Clay Stephenson — Wed, 28 Sep 2005 10:12:33 GMT

Were you conducting these experiments in a very large gravitational field -- perhaps near a black hole? Were tachyons involved? Did you see Captain Kirk?

Re: ping response time

Roberto Volsa — Wed, 28 Sep 2005 11:40:59 GMT

here is an example of results:

64 bytes from 15.156.105.23: icmp_seq=2. time=0. ms
64 bytes from 15.156.105.23: icmp_seq=3. time=0. ms
64 bytes from 15.156.105.23: icmp_seq=4. time=0. ms
64 bytes from 15.156.105.23: icmp_seq=5. time=0. ms
64 bytes from 15.156.105.23: icmp_seq=6. time=0. ms

----hp.italy.hp.com PING Statistics----
2227 packets transmitted, 7 packets received, % packet loss
round-trip (ms) min/avg/max = 300/-2700/1402

Re: ping response time

Bill Hassell — Wed, 28 Sep 2005 11:47:25 GMT

Check for a duplicate IP address for 15.156.105.23. I've seen crazy numbers in ping when there are responses from multiple machines to a single ping. Use arp -a to see what the MAC address is for 15.156.105.23 and verify on that server that it is indeed the same MAC.

Re: ping response time

Alessandro Pilati — Wed, 28 Sep 2005 11:47:44 GMT

Ciao Roberto,

I read somewhere months ago that if average value of ping is negative, the destination address machine could have some operative system problem...

But regard to this wait some guru of the forum for further information...

Best wishes,
Alex

Re: ping response time

Patrick Wallek — Wed, 28 Sep 2005 11:59:56 GMT

What version of HP-UX?

Do a:

# whence ping

And make sure you are using /usr/sbin/ping.

Also do a:

# what /usr/sbin/ping

And post the results. You may need a patch.

Re: ping response time

A. Clay Stephenson — Wed, 28 Sep 2005 12:29:03 GMT

Here is one source for ping but there doesn't appear to be a path that leads to a negative computation --- if I dismiss integer overflow. Note that the tvsub() function out is assumed to be >= in. If that assumption were violated then strange values would be expected. I would be tempted to compile this source (since you could probe it) and look for problems.

http://www.ping127001.com/pingpage/ping.html

NOTE: This is not the HP-UX source for ping.

I suspect that your fundamental problem is such huge packet losses

Re: ping response time

Torsten. — Wed, 28 Sep 2005 12:48:43 GMT

Hi Roberto,

what OS is running on the system where you run your ping command? Most likely the problem is on the source of ping, not on the target.

BTW, a very bad statistic in your post:

2227 packets transmitted

7 packets received

Broken network connection?

Re: ping response time

Roberto Volsa — Wed, 28 Sep 2005 12:59:17 GMT

HI

OS is HPUX 11i

The network is really bad but i wrote wrong number. Percentage of lost packets is less than 1%

Re: ping response time

Bill Hassell — Wed, 28 Sep 2005 14:24:17 GMT

If the network is bad, then I would assume that oddball numbers for ping are normal. If you can't fix the network then it will be quite difficult to get meaningful measurements. Since the travel time is 0 ms, I would assume that this is a local network. Perhaps part of the problem is wih rogue computers (PCs?) with dupliate addresses and badly misconfigured networking, not something that I would ever allow on a prodution network.