Overview
This lecture covers key network devices, their functions, and how they connect and manage various types of network communication in both home and enterprise environments.
Network Devices and Their Functions
- Routers connect different IP subnets and make forwarding decisions based on destination IP addresses.
- Routers can connect different network types (Ethernet, wireless, serial, fiber, copper).
- Switches connect multiple wired devices and forward traffic using destination MAC addresses.
- ASICs (application-specific integrated circuits) in switches enable high-speed data transfers.
- Switches can have many interfaces (24, 48, or even hundreds of ports).
- Power over Ethernet (PoE) allows switches to deliver power and data through the same cable.
Switch Types: Managed vs. Unmanaged
- Unmanaged switches are simple, plug-and-play devices with no configuration options or VLAN support.
- Managed switches support VLANs, remote management, redundancy, traffic prioritization, and port mirroring for monitoring.
- Managed switches use SNMP (Simple Network Management Protocol) and have advanced configuration options.
Access Points and Network Bridging
- Access points connect wireless devices to a wired network by bridging, not routing.
- Access points make forwarding decisions based on MAC addresses, similar to switches.
Patch Panels and Cable Management
- Patch panels terminate Ethernet cables from desks for easy network reconfiguration and management.
- RJ45 connectors on patch panels allow quick changes without disturbing permanent cables.
Firewalls and Network Security
- Firewalls allow or block traffic based on port numbers (traditional) or applications (next generation).
- Some firewalls include VPN concentrator and proxy functionality, and often provide routing between subnets.
Power over Ethernet (PoE) Standards
- PoE supplies 15.4W, PoE+ supplies 25.5W, and PoE++ supplies up to 71.3W for devices like cameras and laptops.
- Inspan refers to switch-supplied PoE; midspan refers to external injector-supplied PoE.
- Higher PoE versions are downward compatible but not upward compatible.
Internet Connectivity Options
- Cable modems use DOCSIS standards for high-speed internet over coaxial cable.
- DSL (Digital Subscriber Line) uses telephone wires for digital internet, with speed affected by distance from the central office.
- Fiber networks use Optical Network Terminals at the demarcation point to convert fiber signals for building use.
Network Interface Cards (NICs)
- NICs provide Ethernet or fiber connectivity for computers and servers.
- Each NIC interface has its own unique MAC address.
Key Terms & Definitions
- Router — Device forwarding traffic between IP subnets using IP addresses.
- Switch — Device connecting devices on a wired network using MAC addresses.
- Access Point — Device bridging wireless and wired networks.
- Firewall — Device controlling allowed/disallowed traffic, sometimes by port or application.
- Patch Panel — Hardware to neatly manage and reroute network cables.
- PoE (Power over Ethernet) — Technology delivering power and data through the same Ethernet cable.
- NIC (Network Interface Card) — Card providing network connectivity to a device.
- Demarcation Point — Boundary where user responsibility ends and provider responsibility begins.
Action Items / Next Steps
- Review PoE standards and device compatibility for upcoming lab.
- Read documentation on managed switch configuration and SNMP features.
- Prepare for cable management exercise using patch panels.