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Unable to ping an ip address from one of two systems. Both systems are on the same subnet going through the same default gateway. Both systems are online.

Posted on 2007-10-16
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Last Modified: 2008-01-09
We have been having intermittent connectivity issues to a database server. Some users occasionally fail to connect to the database and after rebooting their systems they may or maynot be able to connect. I have found out that from my office one system can connect to the database and the other one can't. The system which can connect, is able to ping the server's ip address but the other one isn't. Both systems are able to get to all other network locations. They are on the same subnet and are going through the same gateway. I am not sure if this might be related but this network is primarily using WINS server for name resolution, there is no DNS setup at this point.
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Question by:irtekaz
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Expert Comment

by:A2the6th
ID: 20086942
If you can't ping by IP address you have eliminated WINS or DNS as these only put a name with the IP.  I would look at the local system that can't connect and confirm that the windows firewall didn't get turned on somehow.  

If the firewall is off on the local client, please post the IP address and subnet mask and default gateway of each of the three machines.

Thanks
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Author Comment

by:irtekaz
ID: 20087219
I checked the firewalls. There are no firewalls turned on. Also, the thing is, this is an intermittent issue. The system that isnt' able to ping the server fails about one out of five times. And after rebooting it starts pinging successfully. Sometimes, the other systems fails to ping the server. It almost seems like a network congestion issue. Thats why I mentioned that the network doesn't have DNS becuase I suspect that the Netbios broadcasts might be causing that. But I am not sure.

Here are the IP Adresses, Netmasks and Default gateways.
(this system fails to ping)
192.168.113.116
255.255.255.0
gateway: 192.168.113.2


192.168.113.158
255.255.255.0
192.168.113.2

the ip address of the server (which is located in a differnet city)
192.1.1.29
255.255.255.0
I don't know the default gateway for the remote system
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Author Comment

by:irtekaz
ID: 20087261
Tracing route to 192.1.1.29 over a maximum of 30 hops

  1    <1 ms    <1 ms    <1 ms  192.168.113.2
  2    20 ms    16 ms    21 ms  67.130.156.193
  3    22 ms    26 ms    29 ms  phx-edge-04.ip.inet.qwest.net [205.171.202.61]
  4   114 ms   113 ms   118 ms  65.122.3.210
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9     *        *        *     Request timed out.

the bottom one is the successful tracert from the other system

Tracing route to 192.1.1.29 over a maximum of 30 hops

 

  1     1 ms    <1 ms    <1 ms  192.168.113.2
  2    17 ms    11 ms    11 ms  67.130.156.193
  3    23 ms    22 ms    22 ms  phx-edge-04.ip.inet.qwest.net [205.171.202.61]
  4    57 ms    77 ms    27 ms  65.122.3.210
  5    26 ms    29 ms    26 ms  192.1.1.29

Trace complete.

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Author Comment

by:irtekaz
ID: 20087283
One more thing I would like to mention. This server is running a JDBC database application. I was told that users who are failing to log off are leaving too many connections open to the server which might be causing the server to reject any new connections. I have no idea how that would cause the server to not ping anymore. But I do know that the systems who are pinging successfully are loging on to the database and the systems who fail to ping obviously fail to log on. But some how, rebooting the system a couple of times fixes this issue.
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Expert Comment

by:A2the6th
ID: 20087324
The sever is on a separate network.  That means the traffic from the workstations has to cross a router somewhere.  That might be a good place to start looking at the traffic. (192.168.113.2 is where I would start).  Is it running as it should?

What kind of line to you have between the two networks?  And what is the router on the other side like ( I am referring to the gateway on the 192.168.1.x network)?  

You may also consider looking at the NIC in the suspect workstation since it seems to be the only machine affected by the lag.
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Expert Comment

by:A2the6th
ID: 20087386
It dies at 65.122.3.210 which is a qwest router.  It looks like the next hop is to your internal network meaning  qwest likely has some type of NAT or PAT to your internal network.  

They may also be able to shed some light on why one machine makes it and another doesn't.  

Incidentally the open connections on the DB shouldn't have anything to do with a ping.
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Author Comment

by:irtekaz
ID: 20087411
Thanks for your input, that does explain a few things. However, I would like to mention one more thing. There are several machines on our LAN here that have the same problem intermittently. Users are able to connect to the server one day but the next day they have this problem. And the pinging always coincides with the connectivity to the database application.
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fpcit earned 1500 total points
ID: 20087875
That would rule out an individual NIC but it doesn't rule out saturating the pipe between the two offices.  And each end of the pipe has a router.  Each of those is suspect as well.  

It looks like qwest handles both ends, they can likely supply you with some graphic reports on traffic or maybe they have a monitoring tool you can use to what the pipe and see if the traffic is heavy during these outages.
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Author Comment

by:irtekaz
ID: 20088052
I would really like to thank you again for your input. I will definitely contact Quest. But I have one more piece of information that has me totally confused. Maybe you can make sense of it.

So, I changed the ip address of my machine, from where I was unable to ping the 192.1.1.29 address. I changed my machines ip address from 192.168.113.116 to 192.168.113.220 and I was able to ping the server right away and get on it.

Then I assigned another static ip address to my machine 192.168.113.219. With that Ip address I am unable to ping the server. As soon as I switch back to 220 I can ping it.. 219 doesn't ping it. Neither does 116.  Does that make any sense?
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Expert Comment

by:A2the6th
ID: 20088113
I assume that you checked to make sure no other device on your network has 192.168.113.219 or 116 before assigning it statically.  If you didn't there is potential that you have conflicting IP address and that could cause the outage.  

Outside of that, I would want to look at the routers and see if the have a different subnet configured or have some rule to block a set of IP's

I apologize for pointing you back to qwest but we need some access to those routers to review their config or at the very least see some traffic between the sites.

Thanks
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Author Comment

by:irtekaz
ID: 20088935
Yes actually I did check the addresses and theren't weren't any ip conflicts or blocked ip addresses. I am going to contact Qwest and have them look at their router.

Thanks a lot for your help.
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