connected in the network. Let’s assume that a switch was
just rebooted, and its MAC address table is empty. As the
devices that are connected to the switch start exchanging
data, the MAC address table gets populated with their
addresses. From the first device that sends data on the
network, the switch looks at the source MAC address in
the data frame and records it in the MAC address table,
together with the port on which it received the data.
Since this is the first MAC address in the table, the switch
doesn’t have the destination MAC address of the frame,
so it floods it over all the ports except the port on which
it received the data. As the frame gets flooded
throughout the network, eventually it will get to its
destination. The destination device replies with its own
data frame, in which the source and destination MAC
addresses get swapped. All the other devices drop the
original frame because it was not destined for them. The
switch receives the frame, takes note of the source MAC
address, and records it in its table, together with the port
on which it was received. This way, the switch
dynamically builds its MAC address switching table and
can forward traffic between all the devices that are
connected to it.
ROUTING CONCEPTS
Routing, or Layer 3 packet forwarding, is the process of
selecting a path through a network. To understand
routing, you need to understand IPv4 and IPv6
addresses. Then you can learn about the routing process
itself.
IPv 4 Addresses
The most common protocol at the Internet layer is
Internet Protocol (IP). The Internet, the worldwide
network connecting billions of devices and users, is built
on top of IP. There are currently two versions of IP
available: IP version 4 (IPv4) and IP version 6 (IPv6).