15. Network Switches

Part 15 of Computer Networking Fundamentals: Network Switches

Switches

At the end of this episode, I will be able to:

1. Identify the characteristics and basic functionality of a network switch.

Learner Objective: Identify the characteristics and basic functionality of a network switch.

Description: In this episode, the learner will be introduced to the basics of network switches, the basic is switching process and characteristics of a network switches.

• Introduction to Network Hardware
  • Switches
    • Managed vs. unmanaged
      • Managed switch - this type of switch provides a configuration interface commonly in the form of a command line interface or terminal.
      • Unmanaged - this is the most basic type of switch that requires no configuration tasks and utilizes a sort of "Plug and Play" implementation.
    • Basic components
      • Network adapter - this is a circuit board or embedded component installed on a network device such as a computer, smart tv, gaming console, VoIP phone and more. This component controls the communication for the network device.
      • Network media - this is the bounded connection media that connects the network device to the switch. The most prevalent media is copper twisted pair cabling however fiber optic cabling is also used.
      • Network Switch - this device receives the electrical communications from the network devices connected via ports on the face of the switch. These devices make decisions on what ports to forward the communications to.
    • Media Access Control (MAC) address
      • A MAC address is a unique 48-bit or 6-byte hardware identifier associated with a network adapter. This address is used to identify the network device on Ethernet switched networks.
      • The MAC address is comprised of two components:
        • 1st 3 bytes = Organizationally Unique Identifier (OUI) - a globally unique vendor/manufacturer identifier.
        • 2nd 3 bytes = Unique LAN identifier - uniquely identifies the network adapter within the vendor/manufacturer.
    • The switching process
      • The switch receives a communication frame from a network device connected to one of the switch and adds the Media Access Control address of the network device to a database (MAC Table or CAM Table).
      • The switch inspects the MAC Table for a device connected to a switch port with the matching destination MAC address in the received frame and forwards the data tothe appropriate network device.
    • Switch Characteristics
      • Port Speeds
        • Ethernet = 10 Mbps (10Base)
        • Fast Ethernet = 100 Mbps (100Base)
        • Gigabit Ethernet = 1000 Mbps/1 Gbps (1000Base)
      • Transmission Types
        • Half Duplex - A link that can only communicate in a single direction at a time.
        • Full Duplex - A link that performs simultaneous two-way communications
      • Port Security
        • DHCP Snooping - a technique that controls which ports are allowed to receive DHCP messages.
        • ARP Inspection - a technique that rejects malicious ARP packets
        • Flood Gaurd - a technique that prevents Denial-of-Service (DoS) attacks using malicious broadcast messages.
      • VLANs
        • Allows for the logical division or grouping of a subnet of the network devices connected to the switch.
    • Physical vs. Virtual Switches
      • Physical switch - a tangible hardware connectivity device.
      • Virtual switch - a software-based application/element used in virtualization technologies.
    • Layer 2 vs. Layer 3 switch
      • Layer 2 - A switch that operates in the Data-link layer (L2) of the OSI model
      • Layer 3 - A switch that is capable of using IP addresses, operating on the Network layer (L3) of the OSI model.