ETHERNET

ETHERNET

1. Ethernet protocol

   • Ethernet screen
     • Ethernet encapsulation
       • works on the data link layer and the physical layer.
     • MAC Sublayer
       • the data link layer and is implemented by hardware, generally, in the NIC
     • Evolution of Ethernet
       • standards evolved to specify faster and more flexible versions .
     • Ethernet raster fields
       • Preamble
       • Destination MAC address
       • MAC address of origin
       • Ether type
       • Data
       • FCS
   • Ethernet MAC addresses
     • MAC and hexadecimal address
       • MAC address is a 48-bit binary value expressed as 12 hexadecimal digits
     • MAC Address: Ethernet Identity
       • provides a device identification method at the lower level of the OSI
     • Frame processing
       • destination of an Ethernet frame must have a MAC address
     • Representations of the MAC address
       • can use the ipconfig / all command to identify the MAC address
     • Dirección MAC de unidifusión
       • used when sending a frame from a single transmitting device to a single receiving device.
     • Broadcast MAC address
       • have a destination IPv4 address that contains only one (1) numbers
     • Multicast MAC address
       • source device to send a packet to a group

2. LAN switches

   • MAC address table
     • Basics of switches
       • table of MAC addresses to make a resubmission decision
     • Obtaining MAC addresses
       • MAC address table dynamically after examining the source MAC address
     • Filtering of frames
       • switch's MAC address table contains the destination MAC
     • MAC address tables on connected switches
       • A switch can have many MAC addresses
     • Sending a frame to the default gateway
       • sent to the MAC address of the default gateway
   • Methods of relaying the switch
     • Frame forwarding methods for Cisco switches
       • Storage and shipping switching
       • Switching by cutting method
     • Switching by cutting method
       • Fast forward switching
       • Fragment-free switching
     • Memory buffering on the switches
       • The switch stores the frame until it can be transmitted.
   • Switch port configuration
     • Duplex and speed settings
       • Full duplex
         • the connection can send and receive data simultaneously
       • Medium duplex
         • the connection can send data at a time
     • Automatic MDIX
       • detects the type of cable connected to the port and configures the interfaces

3. Address resolution protocol

   • MAC e IP
     • Destination in the same network
       • Physical address (MAC address)
         • for Ethernet NIC communications to Ethernet NIC in the same network
       • Logical address (IP address)
         • send the packet from the initial source to the final destination.
     • Remote destination network
       • destination IP address is on a remote network, the destination MAC address is the address of the host's
   • ARP
     • Introduction to ARP
       • that has an IP address on an Ethernet network also has an MAC address.
     • ARP functions
       • device searches the ARP table for the destination IPv4 address
     • ARP application
       • needs to associate a MAC address with an IPv4 address and does not have an entry for the IPv4 address
     • ARP reply
       • that has the IPv4 address associated with the target IPv4 address of the ARP request
     • The role of ARP in remote communication
       • device has a packet with an IPv4 address from another network, it encapsulates it in a frame with the destination
     • Deleting entries from an ARP table
       • an ARP cache timer removes ARP entries that have not been used
   • ARP problems
     • ARP broadcasts
       • the local network receive and process an ARP request because it is a broadcast
     • Suplantación ARP
       • used by an attacker to respond to an ARP request from an IPv4 address that belongs