Transcript Internetworking

OSI Model





Discuss the major influences of user
requirements on network evolution
Identify at least 3 reasons why the
industry uses a layered network model
Identify the functions of each layer of the
OSI model
Define and explain 5 steps of data
encapsulation
Build the semester 2 lab topology
User Influence

LANs interconnected to provide access
to computers or file servers in other
locations.

End-user needs for higher bandwidth on
the LANs.

Relaying technologies for WAN service.
OSI Model Review
Identifying Layer Elements
Establishing Communication
Following the
Data
Data will be divided into segments by
the Transport Layer in order to provide
reliable communication between two
computers.
The Network Layer adds source and
destination logical addresses creating a
Datagram (Packet).
The Data Link Layer now puts the
Packet into a Frame to allow
connectivity to other Network devices.
Finally the Frame has to be converted to
a pattern of 1’s and 0’s for transmission
through the media.
Layers 1,2 and 3

Describe the topology and functionality
of various LANs, especially Ethernet

Explain the use of a MAC address

Explain what IP addressing is

Differentiate between IP address classes

Explain what subnet masking is and how
it is used
Ethernet—The first of the major LAN technologies,
it runs the largest number of LANs.
Token Ring—From IBM, it followed Ethernet and
is now widely used in a large number of IBM
networks.
FDDI—Also using tokens, it is now a popular
campus LAN.
Ethernet Topology
Note: E0 indicates that the port is 10 Mb, F0 or Fa0 indicates 100 Mb
Addressing other Hosts
Where is the MAC Address?
Finding someone’s MAC address ARP
Introduction to TCP/IP
Addresses



Unique addressing
that allows
communication
between end
stations.
Path choice is based
on location.
Each location is
represented by an
address.
Making it easier to manage
with subneting.
Layers 4,5,6 and 7


Discuss the function of the application,
presentation, and session layers
qualitatively
Discuss in detail the function and
processes of the transport layer
Application Layer

Supports the communicating
component of an application.
Presentation Layer

Provides code
formatting and
conversion. Code
formatting is used to
make sure that
applications have
meaningful
information to
process. If it is
necessary, this
layer can translate
between different
data formats.
Session Layer

The session layer
establishes, manages,
and terminates
sessions between
applications.
Essentially, the
session layer
coordinates service
requests and
responses that occur
when applications
communicate between
different hosts.
Transport Layer



Transport layer segments the several upper-layer
applications onto the same Layer 4 data stream.
These segmentations allow users to reassemble
the same upper-layer applications at the
destination.
The Layer 4 data stream is a logical connection
between the endpoints of a network.
The Transport layer ensures the integrity and
reliability of the data using a method of flow
control. Flow control avoids the problem of a host
at one side of the connection overflowing the
buffers in the host at the other side.
Major Points

Ensure that segments delivered will be
acknowledged back to the sender.

Provide for retransmission of any segments that
are not acknowledged.

Put segments back into their correct sequence at
the destination.

Provide congestion avoidance and control.
WANs

Describe the purpose of WANs

Describe the characteristics of WANs

Identify Major WAN components
WAN’s purpose



WAN is used to interconnect Local Area
Networks (LAN’s) that are separated by
a large geographical area.
A Wide Area Network (WAN) operates at
the OSI Physical and Data link layers.
The WAN provides for the exchanging of
data packets between Routers and the
LAN’s that the routers support.
WAN’s characteristics



It uses the services of carriers
such as Regional Bell Operating
Companies (RBOCs), Sprint, and
MCI.
WANs use serial connections of
various types to access bandwidth
over wide-area geographies
WAN connects devices separated
by wide areas.
Wan technologies
WAN devices

Routers that offer many services including
internetworking and WAN interface ports.

Switches that connect to WAN bandwidth for
voice, data, and video communication.

Modems that interface voice-grade services;
channel service units/digital service units
(CSU/DSU) that interface T1/E1 services;
Terminal Adapters/Network Termination 1
(TA/NT1) that interface Integrated Services
Digital Network (ISDN) services.

Communication servers that concentrate
dialin and dial-out user communication.


WAN data-link protocols describe how frames are carried between
systems on a single data link. They include protocols designed to
operate over dedicated point-to-point, multipoint, and multiaccess
switched services such as Frame Relay.
WAN standards typically describe both physical layer and data link
layer requirements.