Client connectivity errors are one of the most common sources of network-related problems. Issues range from plain old user error to more complex protocol and cabling issues. Sometimes, even administrators make mistakes that can impact users! With so many possibilities, it is no wonder that client connectivity persists as one of the biggest network troubleshooting hotspots. Protocol ErrorsThe client system must have a protocol assigned or bound to its NIC in order to access resources. You can use various tools to verify that a protocol is being used by the systemfor example, on Windows 2000/XP/2003 systems, you use the ipconfig command; on older Windows client systems, you use the winipcfg command; and on Linux, UNIX, and Macintosh systems, you can use the ifconfig command. Protocol-Specific IssuesYou need to consider a number of factors related to network protocols when you troubleshoot a client connectivity. The following list describes some of the protocol-specific issues you should consider in such a situation:
When protocol settings are correctly configured, protocol problems are infrequent. Unless settings are manually changed, very little can go wrong. AuthenticationBefore users can log on to any system, their identities must be verified. By far the most common type of authentication used is the standard username and password combination. When a user account is created, it is good practice for the administrator to set a password. The user should change that password immediately so that the administrator no longer knows it.
Most user password problems can be traced to users entering an incorrect password or entering the correct password incorrectly. All common operating systems offer the ability for the administrator to change a user's password, but none offer the capability to determine the user's existing password. Therefore, if a user does forget his or her password, a new one has to be created and issued. Permissions ErrorsAccess to applications and data across the network is controlled by permissions. Permissions are responsible for protecting the data on the network and ensuring that only those who should have access to it do. The first rule of permissions troubleshooting is to remember that permissions do not change themselves. If a user cannot access a file, the first question to the user should always be, "Could you ever access the file?" If the user says, "Yes, but now I can't access the file," you should check server change logs or documentation to see if any changes have been made in the permissions structure. If no changes have been made, you should verify that the user is in fact allowed access to that file or directory. In large environments, trying to keep track of who should have access to what can be a tricky businessone that is best left to defined policies and documentation. The following are some other items you should consider when troubleshooting permissions problems:
As with many other IT troubleshooting scenarios, you can solve most permissions problems effectively if you fully understand what you are troubleshooting and the factors that affect the situation. Also in common with other troubleshooting scenarios, you need to approach the problem methodically. Physical Connectivity ErrorsAlthough many of the problems associated with client connectivity can be traced to software-based problems such as configuration, authentication, and permissions issues, physical connectivity is often the root of the problem. When you are troubleshooting physical connectivity errors, the first place to look is at the network cables. Although it is rare, cables can become loose or disconnected from NICs or from the ports on a hub or switch. Oftentimes, this is the result of other cables being plugged in or unplugged, or of other activity on the connections around the one that is having the problem. Other cable considerations include exceeded maximum lengths, cable breaks, and improperly terminated or made cables, although these are only a consideration in exceptional cases. Physical connectivity errors also involve the devices used to establish the physical client/server connectivity. This can include hubs, switches, MSAUs, NICs, routers, and connectivity hardware. Although it is possible to have a problem with a single port on one of the aforementioned devices, it is more likely that the entire unit will malfunction. Thankfully, networking devices are very resilient devices that provide many years of service with few or no problems. |