Ethernet

Ethernet

1. Ethernet encapsulation

   • Ethernet works in the data link layer and in the physical layer.
     • Ethernet supports the following data bandwidths:
       • 10 Mb/s
       • 100 Mb/s
       • 1000 Mb/s (1 Gb/s)
       • 10 000 Mb/s (10 Gb/s)
       • 40 000 Mb/s (40 Gb/s)
       • 100 000 Mb/s (100 Gb/s)
     • Sublayer LLC
       • The Ethernet LLC sublayer handles communication between the upper and lower layers. Generally, this happens between the network software and the device hardware
     • MAC sublayer
       • La subcapa MAC es la subcapa inferior de la capa de enlace de datos y se implementa mediante hardware, generalmente, en la NIC de la computadora.
         • Data encapsulation
           • The data encapsulation process includes frame arming before transmission and frame disarming at the time of reception
             • Data encapsulation provides three main functions:
               • Media access control
               • Error detection
               • Addressing

2. Ethernet frame fields

   • preamble
   • Destination MAC Address
   • source MAC address
   • EtherType
   • Data
   • FCS

3. MAC and hexadecimal address

   • An Ethernet MAC address is a 48-bit binary value expressed as 12 hexadecimal digits

4. MAC address: Ethernet identity

   • In Ethernet, each network device is connected to the same shared medium.

5. Frame processing

   • Often, the MAC address is known as "physical address (BIA)" because, historically, this address is physically recorded in the read-only memory (ROM) of the NIC

6. MAC address representations

   • En un host de Windows, se puede utilizar el comando ipconfig /all para identificar la dirección MAC de un adaptador Ethernet. En la figura 1,

7. MAC Address: Ethernet Identity

   • In Ethernet, each network device is connected to the same shared medium.

8. Frame processing

   • Often, the MAC address is known as "physical address (BIA)" because, historically, this address is physically recorded in the read-only memory (ROM) of the NIC

9. MAC address representations

   • En un host de Windows, se puede utilizar el comando ipconfig /all para identificar la dirección MAC de un adaptador Ethernet. En la figura 1

10. Unicast MAC Address

    • A unicast MAC address is the unique address used when a frame is sent from a single transmitting device to a single receiving device.

11. MAC broadcast address

    • Broadcast packets have a destination IPv4 address that contains only one (1) numbers in the host portion

12. Multicast MAC Address

    • Multicast addresses allow a source device to send a packet to a group of devices.

13. Basic notions of switches

    • A layer 2 Ethernet switch uses MAC addresses to make forwarding decisions.

14. Obtaining MAC Addresses

    • The switch arms the MAC address table dynamically after examining the source MAC address of the frames received on a port

15. Frame Filtering

    • As a switch receives frames from different devices, you can complete the MAC address table by examining the MAC address of each frame.

16. MAC address tables on connected switches

    • A switch can have many MAC addresses associated with a single port. This is common when the switch is connected to another switch.

17. Frame Forwarding Methods of Cisco Switches

    • The switches use one of the following forwarding methods for switching data between ports on the network:
      • Storage and shipping switching
        • In this type of switching, the switch acts on the data as soon as it receives them, even if the transmission has not yet been completed.
      • Switching by cutting method

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