OSI Reference Model and
The Physical Layer
Establish and terminate the physical and
logical connections to the media
Manage the flow and communication on the
Embed the message onto the signal carried
across the physical media
Network Media Type
One of the first LAN media.
it can only carry one message in one direction.
Essentially a tube with an
or plastic core that carries light waves. The
mode cable provides data
transmission rate of approximately 10
gigabits per second over distances of up to
approximately 35 miles.
To send multiple simultaneous signals, networks use a multimode
variant. Multimode transmission speeds are up to 100 Mbps for up to 2
miles, up to 1
for approximately 500 yards, and up to 10
up to approximately 1/5 mile (300 yards).
Twisted Pair Wire
One of the most dominant cabling types in
use today. UTP has no supplemental
shielding, and because the twisting only
provides minimal protection, the cable has
effective limit of approximately
When installing networks in buildings under construction, it is most
beneficial to install networks using physical cable like UTP. UPT is easy to
work with, reliable, less subject to interception or eavesdropping,
The most common alternative when
installing physical cable in existing buildings
becomes too difficult and expensive. The
standard for wireless networks falls under
Wireless Local Area Networks
use one of three
peer (P2P), basic
service set, or extended service set.
Wireless LANs (also called WLANs, or the brand name Wi
Fi) are thought
by many in the IT industry to be inherently insecure. The radio
transmissions used for the wireless network interface between
computing devices and access point (Aps) can be intercepted by any
receiver within range. To prevent this, the networks must use some
form of cryptographic security control.
technology not covered under
the 802.11 standard. Is a de facto industry
standard for short
communications between devices.
To secure Bluetooth
enabled devices you must: 1) turn off Bluetooth
when you do not intend to use it and 2) refuse incoming communications
paring requests unless you know who the requestor is.
A wireless technique for data connections
between personal devices, like personal
(PDAs) and laptops.
The Infrared Data Association (IrDA) defined several standards for short
range infrared connections (typically less than 1 meter). Older IR LANs
Aps in the ceiling, but these were quickly replaced with
Data Link Layer
Primary networking support layer
Provides addressing, packetizing, media access control,
error control, and some flow control for the local
In LANs, it handles client
client and client
Divided in two
Logical Link Control
Primarily designed to support multiplexing and
Media Access Control
Designed to manage access to the communications media(which
clients are allowed to transmit and when)
Ethernet (IEEE standard 802.3)
Fi (IEEE 802.11)
Primary layer for communications between
networks. Has three key functions:
Takes the segments sent from the transport layer
and organizes them into one or more packets for
transmission across a network
Uniquely identify a destination across multiple
The process of moving a Network layer packet
across multiple networks.
The primary function of the Transport Layer is
to provide reliable end
end transfer of date
between user applications.
Responsible for establishing, maintaining, and
terminating communications sessions
between to systems.
Regulates whether communications are
Responsible for data translation and
The user is provided with a number of
services, perhaps most aptly called application
mail (SMTP & POP)
World Wide Web (HTTP and HTTPS)
File transfer (FTP and SFTP)
TCP/IP Layers compared to OSI Layers
Network Interface Cards