Network Troubleshooting Fundamentals

[scuzzman]

Network Troubleshooting Fundamentals

NOTE: This is still a work in progress, so by all means if anyone has anything to add please put it in this thread.

A lot of networking problems can be resolved by use of a few very simple troubleshooting steps. The purpose of this is to outline a few of those steps, and to compliment our pre-existing Wired Networking primers here, here, and here, and our Wireless Networking primer here.

Useful Information:

• The size of your network (# of PC's and routers/hubs/switches)
  
• Your connection type to the internet (most commonly Cable/DSL)
  
• Your router's/gateway's IP address
  
• Whether or not your modem has an internal NAT (most commonly found in DSL modems)
  

IPCONFIG (command-line)

This little jewel comes with every Windows version, and is commonly a main focus of network troubleshooting. Using a string of options, one is able to view and change a number of details about your network connection. The most common incarnations of ipconfig are:

• ipconfig /all - view your network information
  
• ipconfig /release - release your adapter's IP address (usually followed by a renew)
  
• ipconfig /renew - renew your adapter's IP address
  

You can access the command line by going to Start->Run->cmd (WinNT/2000/XP) or Start->Run->command (Win9x/Me).

Graphical incarnations of IPCONFIG

Windows 95, 98, and Me came with a utility called winipcfg. This is available by going to Start->Run->winipcfg. This is simply a graphical frontend for ipconfig, and allows you to release/renew/view details of a connection or adapter.

Windows 2000, as far as I know, doesn't implement a grpahical utility for such a purpose.

Windows XP you can view the adapter information by going to Start->Control Panel->Network Connections. Right-click the connection and hit "Status", then go the "Support" tab. Here you can view the information of the connection, and release/renew the IP address (among other things) using the "Repair" option.

The Powercycle

The simplest troubleshooting step, but most commonly the most effective. This allows each device to refresh their connections, allowing for better network stability and fixing a lot of connection-related problems.

• Power-down all computers
  
• Power-down all routers/hubs/switches
  
• Power down the modem
  
• Now wait 60 seconds then continue
  

The method you use to power-down really isn't that important, it's more the order in which they are powered up:

• Power-up the modem and allow the lights to stabilize (usually takes 10 seconds, but can be up to 2 minutes or more)
  
• Power-up the routers/switches/hubs
  
• Power-up the computers
  

PING

Ping is a very good network diagnostic tool. It is used to check if another device is online, or can be used to check communication between 2 devices. You'll access it through the command prompt, and use it like this: ping ###.###.###.###

where ###.###.###.### is the IP address of the device you're trying to communicate with (such as the IP address of your router, or another computer in the network).

Edit - scuzzman: corrected links for NeoPlanet switch

[homecomputeraid]

Excellent post Scuzzman!

Sincerely,