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Network Problem

Hi,

I have some problem in my network but still I don’t know what is the problem and where is the problem.

Scenario:
I have 5 Cisco Catalyst switch PoE 48 Ports (192.168.50.211 to 192.168.50.215)
I have 1 Cisco Catalyst switch 24 ports (192.168.50.216) another IP (192.168.1.254)

My main switch ip is (192.168.1.254) which is route to (192.168.1.1)
I have 1 Cisco 2800 series router for my outside branches. Which IP is (192.168.1.1) which is route to (192.168.1.6)
I have Cyberoam 250i UTM which IP is (192.168.1.6)

Approximately I have 100 Pcs with laptops and some printers etc. which is connect on my PoE 48Ports switch.
I have 16 to 20 servers.  All servers are connected my 24 Ports Switch.
I have 5 access Point which is also connected to my PoE Switch.

I have Domain controller Active Directory, DNS and DHCP (192.168.1.5)
I have Exchange Server (192.168.1.10)
I have Terminal Server (192.168.1.8)
I have application Server (192.168.1.18)


In my domain controller there is configured DHCP Scope range (192.168.1.101 to 192.168.1.109)

So now when any user connect on  network he get IP address via DHCP
For example. He gets  
IP 192.168.1.127
SM 255.255.255.0
DG192.168.1.254
DNS 192.168.1.5

Last 3 years my network was working perfectly. There was no issue. It was working perfectly fine.

Let suppose we have 50 users and some users has problem.

User1:
192.168.1.127
255.255.255.0
192.168.1.254
192.168.1.5

User2:
192.168.1.141
255.255.255.0
192.168.1.254
192.168.1.5

User3:
192.168.1.117
255.255.255.0
192.168.1.254
192.168.1.5

Now User1 suddenly he has problem. What is the problem that user can’t ping 192.168.1.5 (Domain Controller) but same time he can ping other all Ips on network. At the same time other user can ping domain controller (192.168.1.5)

I try to get reason but I couldn’t. If I log on to domain controller and go to command prompt and type ping 192.168.1.127 –t (User1) so I get request timeout then I right click on my network icon in my domain controller and click repair then I get result on reply form 192.168.1.127.
Then User1 can also ping 192.168.1.5
Same problem is my terminal server (192.168.1.8)

Suddenly User1 complain he can’t ping 192.168.1.8 > I go to my Terminal Server (192.168.1.8) > command Prompt > ping 192.168.1.127 –t > I got request time out > I right click on my network in Termainal server (192.168.1.8) and click on repait > I got reply from 192.168.1.127.

This problem I got any time and any user not only User1. All over net network any user get this Issue. If I don’t do this (repair) may be after few mins or few hours that user is working properly.

I don’t know who to find this trouble shoot. What I have to do.? But at same time which user has problem he can ping all other server.
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shariqsaeed
Asked:
shariqsaeed
1 Solution
 
scollado_pspCommented:
Hi

looks like you have the same IP addres twice in your network, which makes ARP table got crazy. Try to clear arp table on the computer that can't ping (instead of "repair"). If that makes be able to ping again, means that there are two computer with same IP address, which is the problem to solve.

greetings
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shariqsaeedAuthor Commented:
Hi,

there is no same ip on two different pc. if you try to get my scenareo you will understand. very simple example.

I am USER1 I can ping 192.168.1.5 and 192.168.1.8 and suddenly i can't ping these two servers. but same time i can ping may all other network. and same time USER2 Can ping 192.168.1.5 and 192.168.1.8 and all network.
when I log on 192.168.1.5 server and go to command prompt > ping 192.168.1.127  -t (USER1) it give me request time out. and after that if i click on network icon on server and repair i get reply from 192.168.1.127.

this is very strength.
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Ernie BeekExpertCommented:
It looks like some sort of server issue to me. When you look at the event logs on the server(s), does anything show there?
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bbayachekCommented:
Flush your DNS cache on your machines that are having problems. Should be happening automatically but I have seen stale DNS caches screw up a lot of things.
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awender2Commented:
Do you try to ping with IP or DNS? If only with IP, DNS cache doesn't matter. Do you have DHCP exclusions for servers?

If DHCP scope is 192.168.1.101 to 192.168.1.109, then how a user gets 192.168.1.127?
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bbayachekCommented:
@awender2 Ah, yes this is true. It sounds like the explanation is a little "generic"


Are you only giving enough IP addresses to have one per port? Also, do you have wireless access points? This will consume additional IP addresses as well. BUT it shouldn't receive one that is already in use causing pinging in one direction but not the other.

I agree with erniebeek you may want to check yoru DHCP server and make sure there are no errors in the event log. Otherwise you may have a switch configuration problem. Usually if it can ping one way and not the other, one of the switches cannot find it's default gateway (at least in my experience) You can do a traceroute on the IP address and make sure each hop is in there correctly.
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shariqsaeedAuthor Commented:
there was my mistake , DHCP rage is 101 to 209 not 109. that is my mistake to type.

I have got the problem i disconnected my access points and problem has been solved i think some users is connected via mobile on wireless and we got problem inour net work. now i have disconnected all access points network is working smoothly.

thanks for your support.
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shariqsaeedAuthor Commented:
becasue they give me some tips and i was working on it. but the problem is solved by my self.
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