Troubleshooting a Small LAN Problem - Help Needed!

In summary, Blacky thinks that the problem may be with the computer, not the network. He suggests trying to connect the old computer to the network and see if that resolves the issue. Alternatively, he suggests buying a router.
  • #1
BlackJack
59
0
I have a small problem with my lan. The setup is as followed:
The cable modem is connect to a hub, which is connected with my own pc. I used to have an older machine [win2k, normal network card] which had no problems connecting to the network and to the modem. About one week ago I got myself a new pc[winxp pro, gigabite extrem network card from broadcom] which can no longer access the network. The tcp/ip config is the same. The only difference is that I no longer receive data.
Now my question: What should I try? Is there maybe a problem with the lan card?
thanks for your help
Blacky
 
Computer science news on Phys.org
  • #2
I would eliminate the hub first and try connecting that way.
 
  • #3
What for? I know that the modem works since another computer is connected to the hub [win2k] which has access to the internet. I did try to connect using this computers rj45 cable but it still didn't work.
 
  • #4
Could you post the tcp/ip settings for both computers here? Are you specifying a DNS server? Are you using a static ip? Since you have a hub instead of a router you may have to specify these settings.
 
  • #5
Is that a hub or a router? Also, have you run XP's network setup wizard? I've had problems setting up networks manually in XP - it doesn't seem to want to allow it.
 
  • #6
It is a hub and yes I have tried to run the xp config which didn't work as well. Both computers have the same settings. Everything is set to dynamic. No, no fixed ips or dns.
 
  • #7
Do you have the windows firewall enabled? Or any other firewall?

Confirm both PCs are in the same workgroup also.
 
  • #8
You say that you had it working in this configuration previously,

2 computers -> hub -> cable modem


It is not clear to me how it could work. My cable modem wants to talk to a specific MAC address, it will not work with 2 computers on a hub. You need a router which has the MAC address for the cable modem, it then delivers information to the computer which requests it.

Generally the configuration for 2 computers, or more, and no router; is to have a second LAN card in one of the machines. The extra LAN card is connected to the cable modem and ICS is used to control the information flow through the other LAN card to the network.

It seems to me that the cable modem has the MAC address of the 2nd computer and is quite happy talking to it alone. I do not know if you can you make ICS work in the configuration you have.
 
  • #9
Integral said:
You say that you had it working in this configuration previously,
2 computers -> hub -> cable modem
It is not clear to me how it could work. My cable modem wants to talk to a specific MAC address, it will not work with 2 computers on a hub. You need a router which has the MAC address for the cable modem, it then delivers information to the computer which requests it.
Generally the configuration for 2 computers, or more, and no router; is to have a second LAN card in one of the machines. The extra LAN card is connected to the cable modem and ICS is used to control the information flow through the other LAN card to the network.
It seems to me that the cable modem has the MAC address of the 2nd computer and is quite happy talking to it alone. I do not know if you can you make ICS work in the configuration you have.

You are correct.

He said he couldn't access his network which I was thinking are his two pcs.

I was under the impression he could not access his other computer.

He really didn't clearly state the problem.

ICS will not work with the Internet connection running off of the hub. To use ICS you need one NIC for the Internet connection and another NIC to run to the network. ICS is actually kind of like a cheap NAT service.

Blackjack... you can either buy a router or buy a cheap NIC.

If you just want to go cheap, buy one network card and run a standard cat5 to your hub. Then plug the cable modem into your extra NIC and setup ICS. It works the same as a router essentially.
 
Last edited:
  • #10
So if I have understood you correctly : My cablemodem has memorized the mac address of my old computer and won't let me access the connection because my new mac address doesn't correspond with the old one?




[no. no firewalls. What I thought I knew was, that a hub just shares the packets and doesn't bother about anything (which worked fine with the old computer).]
 
  • #11
BlackJack said:
So if I have understood you correctly : My cablemodem has memorized the mac address of my old computer and won't let me access the connection because my new mac address doesn't correspond with the old one?
[no. no firewalls. What I thought I knew was, that a hub just shares the packets and doesn't bother about anything (which worked fine with the old computer).]

Yes your cable modem will only take one MAC address. It has one interface and expects to end on a NIC.

If you unplug your old pc from the hub and reset your modem it will probably lock onto the MAC of your new computer.

A router (at least a home use one) typically has a switch in it as well. A switch is just like a hub except there aren't collisions like there are on a hub. A hub kind of broadcasts information to every connection on the hub. A switch actually only sends the information to the correct port.

A home use router has an internet port and then several switching ports. The router takes that single interface and uses NAT or Network Address Translation to allow traffic from each of the switching ports. NAT is like an intermediate interpreter. It assigns a port or range of ports to each connection on the switch. So when data comes in and out of the router it can interpret where the data goes.

This is why NAT is somewhat secure. If someone does a portscan on your router it will not reveal the open ports on your PC. It will only reveal the ports on the router. If the router has assigned its port 1233 to your PC then to penetrate NAT you have to know the destination computer is behind that port.

This is also why you have to enable port forwarding for web services such as a web server. You have to tell the router to make its port 80, port 80 on a specific PC. Then when incoming requests come into the router it has a static rule to direct traffic.
 

1. How do I troubleshoot a small LAN problem?

To troubleshoot a small LAN problem, start by checking the physical connections of your devices. Make sure all cables are securely plugged in and there are no loose connections. Then, check the network settings on your devices and make sure they are configured correctly. You can also try restarting your router and modem, or resetting them to their factory settings if necessary. If the issue persists, try running a network diagnostic tool or seek help from a network specialist.

2. Why is my LAN connection not working?

There could be several reasons why your LAN connection is not working. It could be due to a faulty cable, incorrect network settings, or an issue with your router or modem. It could also be caused by a software or hardware problem with your device. Try troubleshooting the issue by checking your connections, settings, and restarting your devices. If the problem persists, seek assistance from a professional.

3. What should I do if I can't connect to other devices on my LAN?

If you are unable to connect to other devices on your LAN, try checking the network settings on all devices to ensure they are on the same network. Check the firewall settings and make sure they are not blocking the connection. You can also try restarting your devices or resetting them to their factory settings. If the problem persists, there may be an issue with your router or modem that requires professional assistance.

4. How can I improve the speed of my LAN connection?

To improve the speed of your LAN connection, make sure all devices are connected to a high-speed network. You can also try upgrading your network equipment, such as your router or modem, to a newer and faster model. Avoid using long or damaged cables, as they can slow down your connection. Additionally, close any unnecessary programs or applications that may be using your network bandwidth.

5. What is the role of an IP address in troubleshooting a small LAN problem?

An IP address is a unique numerical label assigned to each device on a network. It helps to identify and communicate with other devices on the network. In troubleshooting a small LAN problem, an IP address can be used to check the network settings on each device and ensure they are on the same network. It can also help in identifying any conflicts or errors in the network configuration.

Similar threads

Using a modem in a LAN to access the Internet
    • Computing and Technology
Replies
27
Views
2K
How to prevent damage to my LAN card due to lightning?
    • Computing and Technology
Replies
15
Views
2K
Set subnet mask to allow connections to two different class c networks
    • Computing and Technology
Replies
13
Views
1K
Changing the LAN card in a CPU
    • Computing and Technology
Replies
17
Views
2K
MODEM Question -- Can a factory reset & re-register clear up intermittent drops?
    • Computing and Technology
Replies
8
Views
2K
Problems with a USB network adapter for a PC
    • Computing and Technology
Replies
15
Views
2K
Best Ethernet / Network switch setup?
    • Computing and Technology
Replies
8
Views
2K
Bluetooth malfunctioning in Ubuntu 20.04 laptop
    • Computing and Technology
Replies
15
Views
4K
Losing Wifi hotspot when connecting to signal
    • Computing and Technology
2
Replies
43
Views
3K
Troubleshooting Unable to Access Router for Security Setup
    • Computing and Technology
Replies
4
Views
3K

Hot Threads

Recent Insights

Back
Top