Essential Networking Devices -Roles, Functions, and Key Details

Router

• Role: routes traffic between different IP subnets
• Details:
  • OSI layer 3 device
  • Routers integrated into switches are sometimes called layer 3 switches
  • connects diverse network types: LAN, WAN, copper, fibre

Switch

• Role: performs bridging in hardware using Application-Specific Integrated Circuits (ASICs), forwards data based on data link (MAC) address
• Details:
  • OSI layer 2 device
  • many ports and advance features
  • core component of enterprise networks
  • may provide Power over Ethernet (PoE)
  • some switches include layer 3 (routing) functionality

Firewall

• Role: acts as a barrier filtering traffic by port number, protocol or application
• Details:
  • can encrypt traffic and provide VPN between sites
  • most operate at layer 3 (can function like routers)
  • often placed at network ingress/egress points
  • support Network Address translation (NAT)
  • may support dynamic routing protocols

IDS & IPS

• Role: IDS detects intrusions and raises alerts, IPS detects and prevents intrusions before they enter the network
• Details:
  • monitor network traffic for suspicious activity
  • identify attacks inbound to the network
  • can detect exploits like buffer overflow, cross-site scripting and other vulnerabilities

Load Balancer

• Role: distributes network or application traffic across multiple servers or devices to improve performance and availability
• Details:
  • manages multiple servers (web farms, database farms)
  • transparent to end users
  • not effected by server outages
  • very fast convergence
• Functions:
  • configurable load distribution
  • TCP offload (handles protocol overhead)
  • SSL offload (handles encryption/decryption)
  • caching for faster responses
  • prioritising traffic (QoS)
  • content switching (application-centric balancing)

Proxy server

• Role: intermediary between user and external networks, forwarding requests on behalf of users
• Details:
  • useful for caching, access control, URL filtering, content scanning
  • explicit proxies require client configuration
  • transparent proxies are invisible to clients

Network attached storage (NAS)

• Role: provides file-level access to shared storage over server

Storage Area Network (SAN)

• Role: provides block level access to storage, appearing as local disk to host
• Details:
  • efficient reading and writing
  • requires high bandwidth, often runs on isolated high-speed networks

Access Point (AP)

• Role: enables wireless communication and connects wireless clients to the wired network
• Details:
  • OSI layer 2 device
  • acts as bridge to extend wired network wirelessly
  • not the same as wired router

Wireless Network

• Role: a network environment composed of multiple access points covering one or more locations
• Details:
  • pervasive convergence with many APs
  • configurations may vary across sites (access points, security...)

Wireless LAN controller

• Role: centralised management platform for multiple access points
• Details:
  • provides a single management interface ("pane of glass")
  • deploys and configures new APs remotely
  • monitors performance and security
  • reports on AP usage
  • usually proprietary and paired with specific AP brands