Network Administration Tools and Techniques

Network Performance Issues

• Common Problem: Network perceived as slow.
  • Often, the network functions properly, but some aspect of communication may perform poorly.

Protocol Analyzer

• Purpose: Captures network frames and presents them in a human-readable format.
• Capabilities:
  • May be built into devices like switches, routers, or firewalls.
  • Can export data to protocol analyzers such as Wireshark.
• Wireshark Features:
  • Shows detailed protocol decodes and conversation analysis.
  • Useful for both network troubleshooting and IT security.

Data Capture and Analysis

• Packet Capture:
  • Store large amounts of data for later analysis.
  • Useful for identifying network issues and security threats.

Network Mapping with Nmap

• Nmap (Network Mapper):
  • Gathers information about open ports, operating systems, and application versions.
• Usage:
  • Active scan; does not require logging into devices.
  • Can scan entire IP ranges to map devices and services.
• Find Rogue Devices:
  • Identifies unexpected devices on the network.
  • Scans on the same subnet, even at Layer Two.

Discovery Protocols

• Cisco Discovery Protocol (CDP):
  • Proprietary to Cisco; provides configuration details without logging in.
• Link Layer Discovery Protocol (LLDP):
  • Vendor-neutral; supported by most switches.
  • Provides information like MAC addresses, VLAN IDs, and interface configurations.

Bandwidth Testing

• Importance:
  • Determines available bandwidth on an internet link.
  • Useful for before-and-after testing of network changes.
  • Bandwidth availability can vary by time of day.
• Speed Test Sites:
  • Variability based on distance and bandwidth constraints.
  • Local ISP tests (e.g., Xfinity, AT&T) often provide the most accurate results.
  • Third-party tests: Fast.com, SpeedOf.Me, SpeedTest.net, TestMy.net.

Summary

• Tools like protocol analyzers and Nmap are essential for identifying and resolving network issues.
• Discovery protocols help in understanding network configurations without direct access.
• Bandwidth testing provides insights into network performance and helps validate configuration changes.