Overview
This lecture covers essential command-line tools and commands used to manage and troubleshoot network switches and routers, focusing on popular network equipment providers and common device features.
Working with Different Network Equipment
- Most network jobs involve using command lines for major equipment providers.
- Command syntax varies slightly between manufacturers, but fundamental concepts and command outputs are similar.
- Familiarity with key commands translates across different network devices as you learn manufacturer-specific syntax.
Key Show Commands for Network Devices
MAC Address Table
- The MAC address table stores learned MAC addresses and the ports they were learned on.
- Use the
show mac address-table command to view all MAC entries and their associated ports.
- This command helps troubleshoot traffic flow and table capacity issues.
Routing Table
- The routing table lists all routes known to the router.
- Use the
show route command to view route entries and help trace network paths.
- Routing table abbreviations (e.g., R for RIP, C for connected) indicate the source of each route.
- Check for the most specific route that matches the traffic.
Interface Status and Performance
- The
show interface command displays interface status (up/down), speed, duplex, errors, and performance stats.
- Information includes hardware details, input/output rates, and error counts like CRC errors.
Configuration Files
- Router and switch configurations can be viewed with the
show config or show running-config commands.
- Config files include interface settings, IP addresses, and device-specific syntax.
- Edits can be made via the command line, then verified by viewing the configuration again.
ARP Table
- The Address Resolution Protocol (ARP) table maps IP addresses to MAC addresses.
- Use the
show arp command to inspect the ARP cache on switches and routers.
- Outputs protocols, IP addresses, MAC addresses, and related interfaces.
VLANs
- VLAN assignments can be viewed with the
show vlan command.
- Displays all VLANs, their assigned interfaces, and the default VLAN for the switch.
Power over Ethernet (PoE)
- The
show power command shows PoE status, power usage per interface, and total available power.
- Helps ensure there is enough power to add new PoE devices.
Key Terms & Definitions
- MAC Address Table — A switch table mapping MAC addresses to physical switch ports.
- Routing Table — A list of network routes and their source protocols on a router.
- Interface — A physical or virtual connection point for network devices.
- ARP Table — A cache linking IP addresses to MAC addresses on a device.
- VLAN (Virtual LAN) — A logical network dividing a physical network into independent segments.
- Power over Ethernet (PoE) — Technology providing electrical power through Ethernet cables.
Action Items / Next Steps
- Practice using
show commands (mac address-table, route, interface, config, arp, vlan, power) on lab equipment.
- Review manufacturer-specific syntax for configuration files.
- Complete any assigned readings or labs related to network management commands.