Chapter 2.5: Network Devices

Routers

◦Their primary function is to route traffic between IP subnets.

◦They make forwarding decisions based on IP addresses.

◦Often connect diverse network types (LAN, WAN, copper, fiber).

◦Routers integrated into switches are sometimes called "layer 3 switches".

Switches

◦Perform bridging in hardware using Application-Specific Integrated Circuits (ASICs).

◦Forward traffic based on the data link (MAC) address.

◦Form the core of an enterprise network with many ports and features, including optional Power over Ethernet (PoE) capabilities.

Multilayer Switch

A type of switch that includes routing functionality.

Unmanaged Switches

◦Offer very few configuration options (essentially "plug and play").

◦Have a fixed configuration with no VLAN support and minimal integration with other devices.

◦Typically have a low price point.

Managed Switches

◦Provide VLAN support and can interconnect with other switches via 802.1Q.

◦Offer features like traffic prioritization (e.g., voice traffic), redundancy support (for uptime), and port mirroring (to capture packets).

◦Allow external management using protocols like SNMP (Simple Network Management Protocol).

Access Point (AP)

◦Not a wireless router (a wireless router combines a router and an AP).

◦Functions as a bridge that extends the wired network onto the wireless network.

◦Makes forwarding decisions based on MAC addresses.

Patch Panels

◦A combination of punch-down blocks and RJ-45 connectors.

◦Cable runs from desks are permanently punched down to the panel, while connections from the patch panel to a switch can be easily changed using patch cables.

Firewalls

◦Filters traffic by port number (OSI layer 4), and some can filter based on the application.

◦Can encrypt traffic entering or leaving the network to protect traffic between sites.

◦Can also proxy traffic as a security technique.

◦Most firewalls can act as layer 3 devices (routers) and typically sit at the ingress/egress (entry/exit) of the network.

PoE (Power over Ethernet)

◦Technology that provides power on an Ethernet cable, allowing one wire for both network connectivity and electricity.

◦Useful for devices like phones, cameras, and wireless access points in difficult-to-power areas.

◦Power can be provided directly by the switch (endspans) or by an inline power injector (midspans).

PoE, PoE+, PoE++

◦Different standards for Power over Ethernet, offering increasing wattage:

▪PoE: Original specification, provides 15.4 watts DC power.

▪PoE+: Provides 25.5 watts DC power.

▪PoE++: Provides 51 W (Type 3) or 71.3 W (Type 4) DC power, with Type 4 supporting PoE with 10GBASE-T.

◦It's important to compare the power requirements of a device with the switch's support.

Cable Modem

◦Uses broadband transmission across multiple frequencies for different traffic types.

◦Carries data on the "cable" network using DOCSIS (Data Over Cable Service Interface Specification).

◦Provides high-speed networking, commonly up to 1 Gigabit/s or more, and supports multiple services like data, voice, and video.

DSL Modem (Digital Subscriber Line)

◦Uses telephone lines for internet connectivity.

◦Characterized by asymmetric speeds, where download speed is faster than upload speed (e.g., 200 Mbit/s downstream / 20 Mbit/s upstream).

◦Has a limitation of approximately 10,000 feet from the central office (CO), with faster speeds possible closer to the CO.

ONT (Optical Network Terminal)

◦Used in Fiber to the Premises deployments.

◦Connects the ISP fiber network to the internal copper network at the demarcation point (demarc).

◦Serves as the line of responsibility where one side belongs to the ISP and the other to your network.

NIC (Network Interface Card)

◦The fundamental network device; every device on a network (computers, servers, printers, etc.) has one.

◦Specific to the network type (e.g., Ethernet, WAN, wireless).

◦Often built into the motherboard or added as an expansion card.

◦Contains the Media Access Control (MAC) address, which is a unique hardware designation.