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Internet nightmare

Discussion in 'Networking' started by soulchyld, Jan 10, 2011.

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  1. soulchyld

    soulchyld Thread Starter

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    Hi, I have a small LAN of about 20 pc's, they are all connected to a BT Business hub, (one of those 2700v things), I have a switch connected to some of the computers and a cisco router connecting the rest, its actually the switch and cisco router that are then connected to the BT Router, problem is I have this intermittent connection to the internet, it seems to be worse when there is lots of traffic on the network, but the thing is I never have any problems with the LAN, even when the internet is down I can still access the LAN, Im fairly new to networking experience wise but theoretically Im fine. can anyone out there suggest some things for me to try?
     
  2. oldrookie

    oldrookie

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    Is there any new configuration or has this confguration been in place for a while and been working until recently??

    When the internet goes down does it go down for all computers/users or only some??

    Also you mention 2 routers - a Cisco and a BT Business Hub. What is that all about?? I can't see whay such a small network would need multiple routers unless one is acting only as modem?? Multiple routers can also lead to problems if they both are acting as DHCP servers. You can use ipconfig /all on a network computer to find out which is acting as DHCP server.

    Normally a small network has a single internet router/firewall and then that device connectes to a network switch that also connects other computers on the network. Of course you can have multiple switches also to expand capacity.

    It is entirely normal for LAN access to remain but the internet be down. The first thing I would try is to power cycle your internet router as often that can fix internet problems. Simply unplug the then internet router/firewall from AC power for 10 seconds or so and then plug it back in. That is kind of like restarting a computer.

    Use ipconfig /all on a couple computers to find the default gateway for the network. Next time your internet goes down see if you can ping the IP of the default gateway or not. If you can ping the defauly gateway then try to ping 4.2.2.1 ( a well known internet server IP) to see if you can ping that or not. If you can then you have basic internet connectivity and if you can not then you do not. If you can ping 4.2.2.1 try to ping google.com to make sure DNS name resolution works or not.

    I would also try to run a different known good network cable between the internet router/switch and the network switch on a different port in case there is a problem there.

    Other problems could be that the internet firewall/router could be going bad, the ISP modem could be going bad, or there simply could be a problem with connectivity from your ISP. You should be able to call them to check that out and they should be able to run line tests to their modem device. ISP modems also have status LEDS that show connected condition. For instance for DSL modems the DSL LED must be solid green or you will not get an internet connection from the ISP.

    Another possibility is that your bandwidth is very limited and too many users could be causing some users to not get internet access or time out. Verifiy your internet speed with your ISP and use Speak Easy Speed Test to verify http://www.speakeasy.net/speedtest/ . Any users streaming audio or video?? Infected computers on the network can also drastically affect internet performance.
     
  3. soulchyld

    soulchyld Thread Starter

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    Thanks, when it goes down I know for certain that its not resolving DNS and at times when you diagnose conectivity issues using internet explorer is comes up with the message DNS server isnt responding, somtimes I can access google using their IP address but if you navigate to another page it fails, sometimes this doesnt work at all, I will try the things you have suggested over the next couple of days and see if that helps, You see it was an existing network (going through the gateway router) and we extended it (thats when the Cisco router came into the picture), I have also suspected the routers could be conflicting because a couple of the machines go through one router, the machines I have added go through the Cisco router, and all this joins up to the BT router which obviously acts as the gateway, I will check again but from what I can remember the machines all use the default gateway of 192.168.1.254, I also suspect the BT line could be dodgy but you know the usual when you fone them up! Another thing I have noticed is the internet goes down on one machine at times, and comes up on another, other times it is down on all machines! the baffling thing to me is its not consistent, making it even more difficult to troubleshoot
     
  4. soulchyld

    soulchyld Thread Starter

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    Another thing is if you reset the router (power it off and back on) the internet comes back but not for long, after my original post I looked at the BT router log and found that it seems to lose the internet connection often,
     
  5. oldrookie

    oldrookie

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    I am not quite sure what you mean by "extending" the network but having a couple routers could certainly cause a problem as you may have some double natting or such going on. Typically you want just a single firewall/router that connects to the "modem/gateway" via its WAN side and the WAN side configured with a static IP whether that be a public IP from your ISP or even a private IP dished out by the modem/gateway. Then that would be the ONLY device connected to the modem/gateway.

    I have seen problems that you describe with multiple routers that the computers can access because each had DHCP server enabled with scopes on different networks with different default gateways.

    Cloud ----> ISP modem/gateway ----> WAN side of firewall/router | LAN side of firewall/router & DHCP server ----> network switch ---> computers
     
  6. geek117

    geek117

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    Unless you have VLANs configured on the switch that need to talk to each other, I can't see a need for your Cisco Router. Is there a Server on the network?

    Also, have you tried updating the firmware on the BT Business Hub?
     
  7. soulchyld

    soulchyld Thread Starter

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    Ok, as I am fairly new to routers and the like, I was only following instructions from someone who obviously isnt as smart as I was led to believe, What is the best for this network setup, to have a switch connecting all the computers and then going through the BT router? it is for basic internet use, of which we would have about 15 users online at any given time!
     
  8. geek117

    geek117

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    You shouldn't have a need for a managed switch (your Cisco unit), unless you're worried about security. And even then, Netgear offers a host of solutions that support VLANs for a whole lot cheaper. Your BT router should provide both routing and switching functions, you simply need something to provide the location with a greater number of ports for internet access. Do you have a server on this network at all?
     
  9. soulchyld

    soulchyld Thread Starter

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    Ok, so I got a bit confused there, dont know how that happened, Its not a cisco router its a switch catalyst 1900 saeries and I guess its there coz of the cost, I have also found there to be another switch on another floor connected to the same bt router!, thing bugging me most is its an intermittent problem some days worse than others, I have checked Ipconfig/all on most of the machines and found nothing amiss, all machines so far are configured to use DHCP, so no IP conflicts, I have a feeling the problem is on the other side of the router, I noticed on the router log that it seems to drop the connection quite often, and reconnects after some time!
     
  10. geek117

    geek117

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    Have you diagnosed the issue with the ISP yet? They should be able to determine if there is a problem with your connection/modem/lines.
     
  11. oldrookie

    oldrookie

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    It sounds like a problem with the BT router or your ISP. Contact them to see what they have to say and find with their tests. If they own the BT router they may replace it.
     
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