RE: Crazy Ping Results

["Pete Peterson" <petersonp genrad com>]

> From: "Taylor, ForrestX" <forrestx taylor intel com>
> To: "'enigma-list redhat com'" <enigma-list redhat com>
> Subject: RE: Crazy Ping Results
> 
> > I have a very strange problem with "ping" in the 7.2 machine that I
> > just loaded from scratch.  If I ping by IP, things look normal; if I
> > ping by name, the name is resolved OK, but I get crazy ping results
> > with times growing by 4 seconds.  Here is an example pinging a machine
> > on our local network (one of our name servers).
> <snip> 
> > **** Note that it pinged (pang?) the same address -- the ping 
> > shows 6 packets with adjacent seq numbers, but there are 31 lost
> > packets (why aren't there seq number gaps?).
> > 
> > Another 7.2 machine on our local net gives normal results, either
> > pinging by name or by IP.
> > 
> > Does this make any sense to anyone?  Once it's resolved the address,
> > why should ping care whether you specified a name or an IP?
> > 
> 
> I have seen this one before, too.  IIRC it had something to do with the
> route.  Check your default gateway and DNS servers.
> 
> Forrest

Thanks for the suggestions, but I'm still bewildered by what I'm seeing:

Well the "host" incantation I showed at the start of the experiment shows
the name resolution working OK.  Being the maintainer of our DNS machines,
I don't believe there's anything strange happening there.  I don't see
anything strange about the routing:

[root torvalds rc3.d]# traceroute 132.223.4.1
traceroute to 132.223.4.1 (132.223.4.1), 30 hops max, 38 byte packets
 1  cisco32.genrad.com (132.223.32.254)  1.378 ms  0.551 ms  0.634 ms
 2  ns1.genrad.com (132.223.4.1)  1.159 ms  0.899 ms  0.771 ms

[root torvalds rc3.d]# traceroute ns1.genrad.com.
traceroute to ns1.genrad.com (132.223.4.1), 30 hops max, 38 byte packets
 1  cisco32.genrad.com (132.223.32.254)  0.551 ms  0.541 ms  0.506 ms
 2  ns1.genrad.com (132.223.4.1)  0.878 ms  0.910 ms  0.770 ms

[root torvalds rc3.d]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
132.223.32.0    *               255.255.224.0   U     0      0        0 eth0
127.0.0.0       *               255.0.0.0       U     0      0        0 lo
default         cisco32.genrad. 0.0.0.0         UG    0      0        0 eth0


The weird thing is that it matters whether I ping by name or by IP.


"ping -R" isn't particularly enlightening either.  It is SLOW and
complains about lost packets, but the routing agrees with the result
from another 7.2 machine on the same subnet.  The other one runs the
traceroute much faster and doesn't lose packets.

[root torvalds rc3.d]# ping -R ns1.genrad.com.
PING ns1.genrad.com (132.223.4.1) from 132.223.32.43 : 56(124) bytes of data.
Warning: time of day goes back, taking countermeasures.
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=0 ttl=254 time=1.440 msec
RR:     torvalds.genrad.com (132.223.32.43)
        cisco4.genrad.com (132.223.4.17)
        ns1.genrad.com (132.223.4.1)
        ns1.genrad.com (132.223.4.1)
        cisco32.genrad.com (132.223.32.254)
        torvalds.genrad.com (132.223.32.43)

64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=1 ttl=254 time=34.142 sec (same route)
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=2 ttl=254 time=38.163 sec (same route)
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=3 ttl=254 time=42.182 sec (same route)

--- ns1.genrad.com ping statistics ---
55 packets transmitted, 5 packets received, 90% packet loss
round-trip min/avg/max/mdev = 1.440/32138.681/46203.062/16563.848 ms


**** here's same thing on another 7.2 machine:

[root grcorpdhcp607 .netscape]# ping -R ns1.genrad.com.
PING ns1.genrad.com (132.223.4.1) from 132.223.52.95 : 56(124) bytes of data.
Warning: time of day goes back, taking countermeasures.
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=0 ttl=254 time=1.612 msec
RR:     grcorpdhcp607.genrad.com (132.223.52.95)
        cisco4.genrad.com (132.223.4.17)
        ns1.genrad.com (132.223.4.1)
        ns1.genrad.com (132.223.4.1)
        cisco32.genrad.com (132.223.32.254)
        grcorpdhcp607.genrad.com (132.223.52.95)

64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=1 ttl=254 time=1.392 msec (same route)
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=2 ttl=254 time=1.355 msec (same route)
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=3 ttl=254 time=1.292 msec (same route)
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=4 ttl=254 time=1.378 msec (same route)
64 bytes from ns1.genrad.com (132.223.4.1): icmp_seq=5 ttl=254 time=1.456 msec (same route)

--- ns1.genrad.com ping statistics ---
6 packets transmitted, 6 packets received, 0% packet loss
round-trip min/avg/max/mdev = 1.292/1.414/1.612/0.103 ms

Both machines are using  2.4.7-10 kernel, though the second machine happens
to be using the SMP kernel.   If recall correctly, the "time of day"
complaint turned out to be a kernel problam and may go away whtn I install
the latest kernel.  However... both machines give that message.

I'm confused!  :-(

       pete

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