Slow LAN Reasons and Solutions

The following paper will show my suggestions solutions for troubleshooting and repairing a slow LAN. Where necessary I have expanded my solution to illustrate my point, but I have tried to be as concise as possible. I exceeded the stated thirty solutions due to the addition of troubleshooting items and other logically included items.

Issue: RAM in workstations.
• Upgrade the amount of RAM.
• Replace with a higher speed RAM.
• Ensure the available RAM exceeds the minimum required for all applications.
• Increase the size of the virtual memory.
CPU in workstations. • Upgrade to a faster CPU.
• Upgrade to a CPU with a larger on board cache.
• Ensure the CPU cooling exceeds the levels required by the manufacturer.

Issue: Increase in number of nodes.
• Segment the network spacing the nodes out equally across the segments.
• Fill the segments as equally as possible considering bandwidth consumption, both average and peak.
• Replace older 10/100 BaseT with Gigabit hardware.
• Replace backbone CAT5 with CAT6 or Fiber.
• Replace hubs with switches for better pass thru and handling.

Issue: Increase in traffic and loading.
• Balance the traffic using either applications or segmenting.
• Replace older 10/100 BaseT with Gigabit hardware.
• Replace backbone CAT5 with CAT6 or Fiber.
• Replace hubs with switches for better pass thru and handling.
• Segment traffic intensive applications such as VoIP from regular traffic.
• Throttle bandwidth intensive applications.
• Schedule bandwidth intensive applications to run on off hours.
• Implement load balancing servers.
• Verify all firewalls are properly configured to only allow necessary traffic through.

Issue: Upgrades in applications (i.e., upgrade in Windows).
• Do not have wide disparity in application versions. (Don't have Win95 machines and XP machines sharing a segment)
• Update all patches and service packs on a routine basis.
• Reanalyze the minimum requirements for new versions and ensure all machines meet those requirements.
• Remove or upgrade all applications that are no longer supported by the vendor.
• Ensure machines have the latest hardware drives and that the drivers meet the requirements of the applications.
• Turn off all bandwidth intensive options until they are proven necessary.

Issue: New applications (i.e., access to Internet). • Ensure all machines running the software exceed the minimum requirements.
• Turn off all bandwidth intensive options until they are proven necessary.
• Update all patches and service packs on a routine basis.
• Verify all firewalls are properly configured to only allow necessary traffic through.

Issue: Increase in graphics use.
• Consider moving hosted graphic intensive applications to a unique server.
• Segment high graphic users from regular traffic.
• Consider nightly transport of graphic files to the local machines versus real-time access.

Issue: Configuration problems.
• Scan network to locate configuration issues and fix either remotely or locally.
• Standardize the load image to ensure machines are properly configured.
• Lock down configuration files to prevent local changes.
• Prevent users from modifying registry and system files.
• Make sure machines are pointing to the proper DNS server and gateway.

Conclusion
One of the most common reasons for a slow LAN in my experience was not listed in the table so I have chosen to offer my solution outside of the table. The first and foremost action I take when I discover a slow LAN is to determine if the problem is due to local traffic or WAN flooding. In our interconnected world WANs are becoming more and more invasive and therefore a traffic study of the WAN as well as the LAN is a must before deciding on a course of action.