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Pinging

By Sprocket ·
I am having a problem on the network where every machine can ping a specific device (say device_X), then during the corse of the day, every machine can ping device_X appart from one specific machine (say PC_X).
Now if device_X is rebooted then PC_X can ping for a while and the it will stop pinging. Every other machine can still ping Device_X and PC_X can still ping everything else.

The route table on PC_X has been reset, it has been rebooted and it is configured like every other machine. The is no conflicting IP Addresses with PC_X, but the IP Address of PC_X cannot be changed.

The thing that is confusing me is that 1) why can PC_X still ping everything else, 2) why can everything else still ping PC_X, 3) why does it work for sometimes a few hours before stopping pinging, 4) why can everything else still ping Device_X.

The one test i cannot perform is pinging from Device_X.

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by hozcanhan In reply to Pinging

sprocket the knot is at device X . You are
i. either using a weird net mask to limit access
ii. or have a max number limit to device x
iii. some sort of an access licence limit.
to do away with a switch port or cable error do a continious ping to PC x , say for half a day . if you get any time outs change your cable or port . may be going 10 to 100 then back to 1o mbits.

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by Sprocket In reply to

If this was the case, why does the problem only happen on one PC.
If there was a limit, cable problem etc, then it would effect more than one PC.

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by hozcanhan In reply to Pinging

sproket , you say that you cannot ping from device X . Shut it down , change the ip of a PC into device X's ip and ping from this source . Secondly , your hints are pointing at either Device PC_X's NIC,cable, rj45 or some kind of a configuration in device X which rejects PC_X. when PC _X cannot ping device X , can pc x be pinged and can it ping the server which has the CALs ?

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by Nico Baggus In reply to Pinging

You might have a problem with arp. which
translated IP adresses to MAC addresses and
back.
The only answer is in the packets on the cable.
Try to get a network dump using ethereal or such
and look when you do a PING what happens do it
on the various systems.
ICMP ping and replay packets are expected and
when there has been a silence for a while
regarding Device_X, its ip address will be lost
from the ARP cache and it will be requiried. If
the ARP query fails, Device_X will become
unreachable.

You will then have to find out Where the arp
goes wrong, it might be at Device_X (limited arp
table?) it doesn't sound right yet. Without the
network trace you realy can't find out what's
wrong or worse were it's wrong.

Compare the dumps from various places.

If device X is a blackbox, plug it into a HUB
(not a switch) plug the hub into the original
port and also hookup a pc with ethereal on it.
Now you can watch all traffic to Device_X
without eve touching it.

I hope this helps a bit
Kind regards,

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by Sprocket In reply to Pinging

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