Ethernet lessons

  • Example of Proxy ARP
    ARP Features

    Static ARP Entries

    Static ARP entry is a permanent IP-to-MAC binding in the ARP table (ARP cache). One reason that you may want to do this is if two nodes in the LAN are constantly communicating and never change their IP and MAC addresses.

  • ARP Security

    ARP vulnerabilities

    Address Resolution Protocol (ARP) has been designed in times when network security has not been very developed. Therefore the protocol is clear text with no embedded security.

  • How ARP works
    What is ARP?

    ARP Role

    Address Resolution Protocol (ARP) is a very fundamental protocol in computer networking.  When a PC wants to send a message over the network, it has to encapsulate the data down the layers of the OSI model.

  • Configuring and Verifying VTP v2

    Configuring VTP

    Verifying the topology

    Before you start configuring VLAN Trunking Protocol on Cisco switches, it is very important to first verify that all inter-switch links are trunks.

  • Example of how Cisco VTP works
    What is VTP?
    VTP is a Layer 2 messaging protocol that was designed to manage the creation and deletion of VLANs and maintain network-wide VLAN database consistency.
  • Frames forwarded in the Native VLAN
    Trunk Native VLAN

    What is the Native VLAN?

    As you remember from the previous lesson, trunk ports send and receive Ethernet frames tagged with IEEE 802.1q VLAN tags.

  • Comparison of PoE/PoE and UPOE/UPOE+ cabling
    Power over Ethernet (PoE, PoE+, UPOE, UPOE+)
    In this lesson, we are going to learn what is Power over Ethernet. What is the difference between the different standards PoE, PoE+, UPOE, and UPOE+? How switches and end devices negotiate PoE settings. How do we configure and verify PoE on Cisco switches and what are the most common use cases?
  • LAN topology with redundant links
    LAN Switching with Redundant Links

    All LAN switching examples up until now were with simple LAN topologies. In the real world, every network topology uses redundant devices and links, because availability is paramount for computer networks. Let's look at how switches behave when there are redundant links.

  • Switching data modes
    Switching modes: Store-and-Forward vs Cut-Through

    As we learned in the previous lesson, the first step in switches' operational logic is to receive an Ethernet frame from the transmitting node.

  • Network with three broadcast domains
    Broadcast Domains

    What is a broadcast domain?

    In Ethernet LANs, a broadcast is one-to-all communication, which means that if a node sends a broadcast frame, everybody receives a copy of it.