Physical Layer OF THE OSI Model
OSI Model
·
Layer 7 = Application:
file, print, message, database, and application services
Layer 6 = Presentation: data encryption , compression and translation services
Layer 5 = Session: Dialog control
Layer 4 = Transport: End to End connection
Layer 3 = Network: Routing
Layer 2 = Data Link: Framing
Layer 1 = Physical: Physical Topology
Physical Layer OF THE
OSI Model
·
Layer 1: Provides the
means for transmitting data packets over a physical medium. Specifies the
electrical and mechanical characteristic of the network. Receives fully
formatted data packets from the Data Link layer. ie Hubs
Technologies that
Function at the Physical Layer
·
Ethernet
2. Fast Ethernet
3. Asynchronous Transfer Mode (ATM)
4. token ring
5. FDDI
Data Link Layer OF THE
OSI Model
·
Layer 2: Responsible
for error free transfer of data packets on a network and for grouping data
packets into frames and attaching the address of the receiving node to each
frame - thus forming the data packet. Also adds error correction and detection
codes to frames. ie switches, PPP and SLIP
Two Sub-layers of the
Data Link Layer
·
MAC
2. LLC
In a contention based
network the MAC sub-layer is responsible for WHAT?
·
For the Carrier Sense
to detect collision. In an Ethernet network it controls elements of addressing
such as error notification ,the frame delivery sequence and flow control.
In a Token Passing
network the MAC sub-layer is responsible for WHAT?
·
For the token.
TCP/IP Model vs the
OSI model
·
APPLICATION - Layer
7-5 (application, presentation and session)
TRANSPORT - Layer 4 (transport)
INTERNET - Layer 3 (network)
NETWORK INTERFACE - Layer 2-1 (data link and physical
Network Design
configurations that are affected by the Physical layer of the OSI model
- Bandwidth of the transmission medium
- Type of transmission medium ie copper
- Switching technologies
- Mode of transmission (wired or wireless)
- Analog or digital transmission
- modulation
MAC Sub-layer of the
Data Link Layer
·
Media Access Control:
Defines how packets are placed on the media.
LLC Sub-layer of the
Data Link Layer
·
Logical Link Control:
- ID's Network Layer protocols and encapsulating those protocols so that
multiple upper layer protocols can share the same media.
- Controls the Physical Layer device and also performs error control.
-Checks the CRC of the frame and either ACK or NACK the data.
-Controls data flow to maintain the bandwidth of the network medium.
-Tells the Data Link Layer how to handle the frame it receives.
Network Layer OF THE
OSI Model
·
Layer 3 - Responsible
for addressing and routing the data packets from a source to a destination
through a network. Ensures delivery of packets across a network. Responsible
for controlling congestion on the network by taking proper routing decisions.
ie routers and some switches
Transport Layer OF THE
OSI Model
·
Layer 4 - Accepts data
from upper layers and breaks it into smaller units, aka segments. Passes the
segments to the lower layers and ensures that all segments arrive correctly at
the receiving end. Adds a sequence number to reconstruct original sequence of
segments. Responsible for error correction and sending acknowledgments at the
network level.
What are the protocols
that operate at the Transport Layer?
·
TCP (transmission
control protocol)
UDP (user datagram protocol)
IPsec
PPTP (Point to Point Tunneling Protocol)
RDP
L2TP (Layer 2 Tunneling Protocol)
Network Layer OF THE
OSI Model defines protocols for interconnecting two or more similar networks
such as these....
·
IP
ARP (address resolution protocol)
ICMP (internet control message protocol)
DHCP
RIP (routing information protocol)
OSPF (open shortest path first)
BGP (boarder gateway protocol)
IGMP (internet group management protocol)
Network and Transport
Layer Protocols contain protocol families. What are the 3 categories?
·
1.Reliability
2. Connection
3. Routing
Reliability Protocols
·
Provides a method of
ensuring reliable data transfer. ie.. A header or trailer might contain a
Checksum value or request that you need to acknowledge received data by sending
an acknowledgement message back to the sender. TCP (transmission control
protocol)
Connection Protocols
·
Establish and maintain
a connectionless or connection-oriented service for the upper layers. In a
connection-oriented service, the sending and receiving nodes maintain constant
communication to mediate the transfer of data. Sequencing, flow control and
reliability are monitored at both ends. In a connectionless service, the
message is packaged, delivered and sent. the message is transferred only if
communication exits between the two nodes. UDP (user datagram protocol)
Routing Protocols
·
Provides a method of
ensuring data transfer to the correct destination. In an unswitched network,
routing is virtually unnecessary because the nodes are directly connected. In a
switched network, the routing protocol determines the path a packet will take
to reach its destination. this function is particularly important and complex
in a packet-switched network, because there can be many possible paths to a
destination and many intermediary devices such as routers along the path.
Routing protocols determine the strategies used to transmit data through the
network. RIP, OSPF, PPTP
Checksum Value
·
Lets the receiver test
the integrity of received data.
Session Layer OF THE
OSI Model
·
Layer 5 - Establishes
connections between network devices and applications, maintains the connection,
and then terminates or reestablishes it when required. Controls how, when and
for how long a device can transmit or receive data. Specifies procedures for
synchronizing data transfer between two devices with different data
transmission rates.
Sockets and session
establishment in TCP function at this OSI layer
·
Session Layer
Gateways operate at
this OSI layer. Ports are referred here also
·
Transport Layer
Presentation Layer OF
THE OSI Model
·
Layer 6 - Responsible
for encoding data into a standard network-compatible format, which enable devices
with different representation techniques to communicate with each other. Adds
services such as data compression and encryption.
What are the
technologies and protocols that operate at the Presentation Layer?
MME (mesh made easy)
·
SSL (secure socket layer)
TLS (transport layer security)
GIF (graphics interchange format)
JPEG (joint photographic experts group)
TIFF (tagged imaged file format)
Application Layer OF
THE OSI Model
·
Layer 7 - Offers
services and utilities that enable application access to the network and its
resources.
What are the
technologies and protocols that operate at the Application layer?
·
HTTP
DNS
FTP (file transfer protocol)
Gopher
NFS (network file system)
NTP (network time protocol)
SMTP (simple mail transfer protocol)
SNMP (simple network management transfer protocol)
Telnet
What are the 7
Application, Presentation and Session layers protocol families (aka Application
layer of the TCP/IP model)
·
Terminal-Emulation
protocols
2. File access and file transfer protocols
3. Email protocols
4. Remote-action and multiple-session protocols
5. Network management protocols
6. Task to task protocols
7. Codeset and data structure protocols
Terminal-Emulation
protocols
·
Allow the user access
to a text terminal and all its applications. Enable computers to act as
standard terminals so that they can access hosts.
File access and file
transfer protocols
·
File access protocols:
enable nodes to access files on the network. provide a common means to access
network files.
File transfer protocols: Enable copying of files between network storage and
other storage, such as a computers local disk drive.
Email protocols
·
Provide for email
delivery and handling of messages
Remote-action and
multiple-session protocols
·
Remote-action protocols:
Determine whether processes should be performed remotely on a client node or
directly by a server. Required for setting up a client-server relationship.
Multiple-session protocols: Enable multiple network links to be established.
Network management
protocols
·
Provide tools for
setting up and maintaining the network
Task to task protocols
·
Enable software
processes to communicate over the network.
Codeset and data
structure protocols
·
Define the
representation of data. Translate data for nodes that use different coding
schemes.
The OSI Data
Communication Process
·
Sender goes through
the model from 7 to 1. the receiver goes from 1 to 7.
Application Layer of
the TCP/IP network model
·
Provides definition of
protocols for file, mail and hypertext transfer. Handles the encoding of data
and controlling of the sessions. Defines socket services and other utilities
over TCP/IP.
Transport Layer of the
TCP/IP network model
·
Provides connection
establishment and communication services. Defines protocols for end to end
transfer of data, along with error and flow controls.
Internet Layer of the
TCP/IP network model
·
Provides addressing
and routing services. Controls congestion on the network. Involves transferring
data from a source to destination network when multiple networks are connected
together.
Network Interface
Layer of the TCP/IP network model
·
Provides services to
send and receive data packets on the network. Defines protocols for moving data
frames between adjacent nodes and for accessing the medium by the devices.
Defines the protocols for encoding and transmitting data over the network
media.
OSI was developed to
standardize networking. TRUE/FALSE
·
True
TCP/IP model was
specifically developed to execute Internet related tasks. TRUE/FALSE
·
TRUE
The OSI model was
invented after protocols
·
FALSE
TCP/IP protocols are
the standards around which the Internet was developed. The functionality
allotted at each layer is perfectly optimized.
·
TRUE
In the TCP/IP model
each layer uses different terminologies for a unit of information. What are
they?
·
Application - Data
Transport - Segment
Internet - Datagram or packets
Network Interface - Frames
Data Encapsulation
·
Process of adding
delivery information to the actual data transmitted on each layer. Takes place
in the transmission end as data is passed down the layers. At the receiving
end, the reverse process of removing the added information is done as data
passes to the next higher layer in a process called de-encapsulation. The added
information is called a header if it is before the data or a trailer if it is
added after the data.
Protocol Binding look
·
Assigning a protocol
to a NIC. This creates a path for the flow of data. In windows you can specify
the binding order in which to bind protocols to a NIC.
Windowing
·
The quality of data
segments, measured in bytes, that the transmitting machine is allowed to send
without receiving an acknowledgement.
You will find Bridges
and switches on what layer?
·
Data link layer
What layer is
responsible for converting data into signals?
·
Physical layer
What are two purposes
for segmentation with a bridge?
·
To create more
Collision domains and to add more bandwidth for users
Which layer 1 devices
can be used to enlarge the area covered by a single Lan segment?
·
Hub and repeater
Service Firms vs.
Manufacturing Firms
·
Manufacturing firms -
produce tangible, physical goods, such as cars or food products
Service firms - produce nonphysical outputs in the form of services, such as
medical and transportation services
>Economy is dominated by creation and sale of services
Value Chain Management
·
Value - the
performance characteristics, features, and attributes, and any other aspects of
goods and services for which customers are willing to give up resources for
(usually money)
>Value is provided to customers through transforming raw materials and other
resources into some product or service that end users need or desire when,
where, and how they want it
Value chain management - the process of managing the sequence of
activities and information along the entire value chain
>Externally oriented and focuses on both incoming materials
and outgoing products and services
>Effectiveness-oriented and aims to create the highest value for customers
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