Cisco router fault?

Unanswered Question
Sep 9th, 2010
User Badges:

Hi guys,


I have a network of 5 computers.
One of the computers doesn't load the www.vmware.com website. The other computers is loading the website fine.


Internet is coming through a ADSL2+ modem, after that a Cisco router with DHCP enabled.


What I have done without any result:
- tried with different IP
- tried with different MAC address
- clear the cache
- deleted the cookies
- tried with different browser (Internet Explorer & Mozzila Firefox)
- tried with different operating system (Windows & Linux)
- tried with different network cable (known good)
- tried with different DNS
- tried to acces the website by IP address
- checked if there is something which is blocking the website
- firewall off
- tried to connect the "guilty" computer into other port in Cisco router


When I connect to the internet through a 3G modem (without passing Cisco router) works perfect, so the operating system is OK.
When I connect to the internet directly from the ADSL2+ modem everything is fine, so the ethernet port is OK.


My problem:


Why just one computer has these problems and the rest of the computers don't?
It is weird that all the computer have acces to internet through Cisco router, but just one of them has this problem.


Any idea?


Thanks.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Federico Coto F... Thu, 09/09/2010 - 22:07
User Badges:
  • Green, 3000 points or more

Is there any chance that the router has an ACL denying access to the IP address of this website from the IP of the internal computer?

Eventhough the computers get IP via DHCP, there's a chance that everytime you have tried this, the router has assigned the same IP to that computer and that will explain the behavior.


Otherwise it seems very odd.

If the problem persists, you could try capturing the packets through the router to check the path of that computer when going to that site and see if the router is doing something to drop that connection.


Federico.

navigatoru Thu, 09/09/2010 - 22:25
User Badges:

Unfortunatelly I don't have acces to the Cisco router to check if it has an ACL.

The IP was manually asigned to that computer with an IP address which was working without any problem.


All the computer is working fine (is loading that website) excluding the gulty computer.


Thanks.

james.mirtsis Thu, 09/09/2010 - 22:30
User Badges:

ok to rule out an access list, change the ip address of the guilty computer to an ip address of a good computer and take the

good computer off line. if it still doesnt work then its not the router.


another possible place to check is the hostfile on the guilty computer to ensure there is not a dodgy mapping of the url to a 127.0.0.1 or any other bogus address. just google host file for the operating system you are using to ffind where it is located. also you could try disabling any firelwalls running on the pc as another option, windows firewalls need to be stopped in process as they will continue to run anyway if you disable them on the nic.

navigatoru Thu, 09/09/2010 - 22:41
User Badges:

I already did. I changed the IP address from the guilty computer with the good one - no result

I checked the hostfile (Windows XP) and looks fine (127.0.0.1      localhost)

I killed the firewall process - no result



In addition, as I wrote, I tried with a separate operating system (Linux), and is the same result - not working.

When I connect the computer directly to the internet (bypass the Cisco router), is working fine.


It is very weird for me this.

james.mirtsis Fri, 09/10/2010 - 01:31
User Badges:

Sorry I missed that part. with the host file i meant check if www.vmware.com had a bad address, not look at the local host address. However if you can reach the url when bypassing the router then it is clearly the router causing the problem, and there is nothing wrong with the hostfile.


Let me just recap the steps so far & please fill in anything I have left out:


pc's can reach the url through the router excpet for the bad one

changing the ip address of the bad one to a good address doesnt work either

A new pc running linux cannot reach the url either

bypassing the router, the bad pc can reach the url


Question for you. Can the bad pc reach any websites through the router?


It could be a few things but without getting into the router I dont think you will have much luck I am affraid. Can you get the password to the router? Are you allowed to do password recovery on the router? I would try to get access to the router to find out what is happening or ask the authorised people that can access the router to take a look and maybe give you a copy of the config. Try running a packet capture on the bad machine see what response the router is giving you if any when you try to hit the url.


james.mirtsis Thu, 09/09/2010 - 22:18
User Badges:

when you say you have tried with a different ip, did you statically assign an ip to the client? becuase your router is running dhcp, and if you release/renew your ip on your client you will nearly almost get the same ip again unless you assign that ip to another client.


a show run from your router and an ipconfig /all (if windows) pc would be helpful to proved advice here.

navigatoru Thu, 09/09/2010 - 22:27
User Badges:

when you say you have tried with a  different ip, did you statically assign an ip to the client? becuase  your router is running dhcp, and if you release/renew your ip on your  client you will nearly almost get the same ip again unless you assign  that ip to another client.


a show run from your router and an ipconfig /all (if windows) pc would be helpful to proved advice here.



yes, was manually asigned the IP address.

unfortunatelly I don't have access to the router so I can't issue commands to the router.


I know that is not so good for troubleshooting, but these are the conditions.


thanks

Actions

This Discussion

Related Content