Strange Network Problems

readymixed1 · ‎10-24-2008

I have a strange network problem here, and it seems to be growing.

Here's the problem:

I have a computer that has a IP address of 192.168.1.12 and it can ping every IP address in the 192.168.0.X and 192.168.1.X networks except for 192.168.1.175. Although if I manually set the IP address to 192.168.1.13 it can ping 192.168.1.175 without any problems. But if I set it back to 192.168.1.12 it can't ping 192.168.1.175.

This problem is now starting to happen with my print server not being able to see this one printer but all the other servers can ping and see this printer. I have to either restart the server for it to see it again or rebuild the TCP/IP stack.

So as you can see this is happening on more then one machine.

Any ideas?

jestin.vj · ‎10-24-2008

Hi Dear,

I hope that 192.168.1.175 is static IP and others are dynamic IPs.(xxx.175 is not a computer I think) Even if you are unable to ping xxx.175, u can use its service.

Its because, xxx.175 is staticaly assigned IP and xxx.12 is dynamic IP.

I too had faced this problem with my Network. I was unable to ping my wireless device which had static IP,(My laptop had dynamic IP) but I could login to it and work on it remotely. But when I change Laptop IP to static IP, I could ping and login.

Just try this once

jim.reynolds · ‎10-27-2008

Sounds like it could be a duplicate IP assignment or an ARP problem.

You really need to provide more information. Given the information the problem could be caused by L2 or L3 issues so you need to provide more info to narrow it down. What type of switches/routers, L2 & L3 topology etc.

readymixed1 · ‎10-28-2008

The same problem is happening with some of our printers as well. The 192.168.1.175 and all the printers have a static ip address.

The print server also has a static ip address (192.168.0.15) and it can't ping printer (192.168.0.51). Although my PC (192.168.0.137) can ping printer (192.168.0.51).

It seems to fix the problems when I rebuild the TCP/IP stack on the computer or server. Although it only works for a few weeks to a month and then it messes up again.

We are running in an AD Domain. We have 2 networks in this building 192.168.0.X and 192.168.1.X

All 192.168.0.X network is static assigned. Most of 192.168.1.X network is DHCP except for 192.168.1.150 - 192.168.1.254 is static IPs for more servers.

We use a 7 stack of Catalyst 3750g's to serve as our switches/routers.

The topology is Star. All workstations connect to a patch panel which then feeds into the stack of 3750g's.

dany.datacraft · ‎10-29-2008

It looks like an ARP problem to me.

Do a 'arp -a' when you are pinging from your PC (or print server) and check the MAC address of the printer against the actual one.

readymixed1 · ‎10-30-2008

I went to do that on the print server but it some how is back online at least for now. If it does it again I will check the arp for that printer. How do I clear arp within Windows Server 2003? I know on XP when you do a repair it clears it automatically for you.

Also back to my other problem where 192.168.1.12 (if you assign that IP address to any computer) can't ping 192.168.1.175 but can ping any other computer with no problems. You think that's an arp problem on the switches/router and the arp table needs to be cleared?

dany.datacraft · ‎10-30-2008

Try 'arp -d'

192.168.1.12 and 192.168.1.175 (subnet mask 255.255.255.0) are on the same subnet, so ARP problem should be on the end nodes.

If ARP is correct, you will need to check the mac-address-table on the switches, make sure the MAC addresses are detected on the correct ports. The command is 'show mac-address-table dynamic' on the switches.

readymixed1 · ‎10-30-2008

"ARP problem should be on the end nodes." -

So your saying the problem maybe on the 192.168.1.175 node since no matter what machine I put 192.168.1.12 on it can't ping 192.168.1.175 (but if i use 192.168.1.13, it can ping 192.168.1.175).

The MAC addresses seems ok in regards to the ports they are on. What happens if there is a problem though? How do I clear the MAC Address table? Also how do I clear the ARP table on the switches?

Clearing the MAC and ARP table doesn't cause the network to go down any right?

dany.datacraft · ‎10-30-2008

Yes, you are correct. Unfortunately I don't know how to check ARP table in printer :). Perhaps reboot would be an easier solution.

Clearing ARP table on switches - 'clear arp'

Clearing MAC Address table - 'clear mac-address-table'

No, clearing MAC and ARP table should not cause network to go down.