Download Collision domains vs. broadcast domains.

Special IP Networking Concepts
Lesson overview.
In this lesson, we will cover:
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The media access control address.
Collision domains vs. broadcast domains.
Types of network transmissions.
The media access control address.
All networking interfaces come with a special address already configured—the media access
control (MAC) address. The MAC address is often referred to as the physical address or the
burned in address of the interface. While the MAC address may be changed (or spoofed), most
often it is set by the manufacturer and never changes.
Switches and other Open Systems Interconnection (OSI) Layer 2 (data link layer) devices rely
upon the MAC address in order to get network packets to the correct destinations.
Highlights:
All networking interfaces come preconfigured with their own special address—the media access
control (MAC) address. The MAC address is often referred to as the physical address or the
burned in address of an interface. While MAC addresses may be changed or spoofed, most
often they are set by the manufacturer and never actually change. Switches and other OSI
Layer 2 devices rely upon MAC addresses in order to get network packets to their correct
destinations.
MAC address format.
A MAC address on a device will either be 48 bits in length or 64 bits in length. Both of these
formats are represented by hexadecimal numbers. Both formats can also be broken down into
two parts—the Organizationally Unique Identifier (OUI) and the Extended Unique Identifier
(EUI).
The Institute of Electrical and Electronic Engineers (IEEE) assigns all electronic manufacturers
their own OUI, which always makes up the first portion of a MAC address. Each manufacturer
then assigns its own EUI to each device that is produced. Usually, the EUI is the serial number
of that device. Theoretically, no two interfaces will have the same MAC address.
Highlights:
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MAC addresses come in either 48 or 64 bits in length and are represented by
hexadecimal numbers.
Both formats can be broken down into two parts—the OUI and the EUI.
Theoretically, no two interfaces will have the same MAC address.
EUI-64
IPv6 requires that the node address, or the MAC address, be in an EUI-64 format, so that MAC
address has to be 64 bits in length. If the EUI of the interface is only 24 bits in length, it is
actually split into two parts and 16 bits of padding are added to create the EUI-64 format.
Highlights:
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IPv6 requires that the node address be in an EUI-64 format.
•If the EUI of the interface is only 24-bits in length, it is split into two parts, and 16-bits of
padding (fffe) are added to create the EUI-64 format address.
Collision domains vs. broadcast domains.
Carrier Sense Multiple Access With Collision Detection (CSMA/CD).
Ethernet networks use a technology called Carrier Sense Multiple Access With Collision
Detection (CSMA/CD) when transmitting data. All Ethernet devices have equal access to the
network media and are capable of transmitting data at any time. This can lead to data collisions.
With CSMA/CD, a device listens to the carrier signal on the network media. If no other device is
transmitting, the device is free to send data. If another device sends data at the same time, a
collision is possible, which can corrupt the data. The devices listen for collisions. If a collision
occurs, the devices will stop transmitting and wait a random period of time before attempting to
transmit again.
Highlights:
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All Ethernet networks use CSMA/CD when transmitting data.
All Ethernet devices have equal access to the network media and are capable of
transmitting data at any time, making a data collision possible.
With CSMA/CD, a device listens to the carrier signal on the network media. If no other
device is transmitting, the device is free to send data.
If a collision does occur, the devices will stop transmitting and wait a random period of
time before attempting to transmit again.
Collision domains.
Collision domains are an area of the network where packets or network traffic can collide. There
are some devices that break up collision domains. They can be broken up by switches, bridges,
and routers, but not by hubs.
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An area of the network where network packets can collide.
Collision domains are broken up by switches, bridges, and routers—but not by hubs.
Broadcast domains.
Broadcast domains are defined as all the nodes that can be reached by a broadcast
transmission. All the nodes that can be reached reside within the same network. Broadcast
traffic cannot pass routers, so the domain is also defined by the subnet mask in that the subnet
mask defines the network. Technically, IPv6 does not use broadcast transmissions. IPv6
replaces broadcast transmissions with multicast and anycast transmissions.
Highlights:
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A broadcast domain is defined as all the nodes that can be reached by a broadcast
transmission.
Broadcast domains cannot pass routers, so the domain is also defined by the subnet
mask (last available address that is allowed by the mask).
Technically, IPv6 does not use broadcast transmissions—replaced by multicast and
anycast.
Types of network transmissions.
IPv4 network transmission types.
When transmitting data, IPv4 supports three types of network transmissions. They are outlined
below.
Unicast.
A unicast transmission involves a specific source address transmission going to a specific
source destination address. It can be thought of as one-to-one communication. Unicast is two
devices transferring data between each other.
Multicast.
A multicast transmission is where a specific source address transmission is going to a set of
registered destination addresses. This is one-to-a-few communication. Routers often use
multicast transmissions to track their routes and to make changes to the routing cables.
Broadcast.
A broadcast transmission is where a specific source address transmission is going to all
addresses on the local network. This can be considered as one-to-all communication, because
all devices on the local network are going to be able to receive this broadcast transmission.
Highlights:
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A unicast transmission is one-to-one communication involving a specific source address
transmission going to a specific source destination address.
A multicast transmission is one-to-a-few communication, with a specific source address
transmission going to a set of registered destination addresses.
A broadcast transmission is one-to-all communication with a specific source address
transmission going to all addresses on the local network.
Types of IPv6 network transmissions.
IPv6 uses two of the three network transmission types that are used in IPv4—unicast and
multicast. Where IPv6 differs is with the use of anycast transmissions.
Anycast.
An anycast transmission is where a specific source’s address transmission is going to a specific
IPv6 address, which has been assigned to multiple devices. When sending an anycast
transmission, the router uses an algorithm to determine which MAC address—that has that
specially configured IPv6 address—is closest. And only that device receives the anycast
transmission. Anycast can be considered as one-to-the-closest communication.
Highlights:
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An anycast transmission is one-to-the-closest communication where a specific source
address transmission going to a specific IPv6 address that has been assigned to
multiple devices.
With anycast, the router uses an algorithm to determine which MAC address is the
closest and only that device receives the anycast transmission.
What was covered.
The media access control address.
All network devices come with MAC address (also called the physical address or burned in
address) which are used by Layer 2 network devices to deliver network packets to the correct
nodes on the network. The MAC address is composed of the OUI, which is assigned by the
IEEE and the EUI, which is assigned by the manufacturer. IPv6 requires an EUI-64 format
address.
Collision domains vs. broadcast domains.
Ethernet networks utilize CSMA/CD to alleviate network traffic collisions. Collision domains are
areas of the network in which network traffic can occur. Collision domains are broken up by
Layer 2 and higher devices. Broadcast domains are areas of the network that will receive
broadcast network traffic. IPv6 uses multicast transmissions in place of broadcasts.
Types of network transmissions.
IPv4 uses unicast (one-to-one communication), multicast (one to a few communication), and
broadcast (one-to-all communication) network transmissions. IPv6 also uses unicast and
multicast transmissions. In addition, IPv6 uses anycast (one-to-the-closest) network
transmissions to deliver network traffic to the nearest device that has a specific IPv6 address,
which has been assigned to multiple devices.