Network protocols

1. Network
Architecture
PROTOCOL
Jan-19-2016

2. Protocols
• The term protocol refers to a well-known set of rules and
formats to be used in order to perform a task. For
example, a task of communicating between processes.
• Parts of a protocol:
- A specification of a sequence of messages that must
be exchanged.
- A specification of the format of the data in the
messages.
• Existence of well-known (standard) protocols enables the
separate components of the distributed systems to be
developed independently in different languages and on
different platforms.
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?
What is
a

3. 3elements of a protocol:
• Syntax
- structure of
commands
and answers
• Semantics
- set of commands
and answers
• Timing
- temporal
sequence of
commands and
answers

4. How Protocols Work ?...
The entire technical operation by which data is transmitted
over the network has to be broken down into discrete, systematic
steps. At each step, certain actions take place that cannot take place
at any other step. Each step includes its own rules and procedures,
or protocol.
The protocol steps must be carried out in a consistent order
that is the same on every computer in the network. In the sending
computer, these steps must be executed from the top down. In the
receiving computer, these steps must be carried out from the bottom
up.

5. Protocols at the sending computer:
1. Break the data into smaller sections, called packets, that the
protocol can handle.
2. Add addressing information to the packets so that the
destination computer on the network can determine that the
data belongs to it.
3. Prepare the data for transmission through the NIC and out
onto the network cable.
The Sending
Computer
How Protocols Work ?...

6. Protocols at the receiving computer carry out the same series of
steps in reverse order. They:
1. Take the data packets off the cable.
2. Bring the data packets into the computer through the NIC.
3. Strip the data packets of all the transmitting information that
was added by the sending computer.
4. Copy the data from the packets to a buffer for reassembly.
5. Pass the reassembled data to the application in a usable
form.
The Receiving
Computer
How Protocols Work ?...

7. Both sending and receiving computers need to perform
each step in the same way so that the data will have the same
structure when it is received as it did when it was sent.
For example, two different protocols might each break
data into packets and add on various sequencing, timing, and
error checking information, but each will do it differently.
Therefore, a computer using one of these protocols will not be
able to communicate successfully with a computer that is using
the other protocol.
How Protocols Work ?...

8. Protocol Stacks
A protocol stack is a
combination of
protocols. Each layer
of the stack specifies
a different protocol for
handling a function or
subsystem of the
communication
process. Each layer
has its own set of
rules.
Application Layer
Presentation Layer
Initiates a request or accepts a
request
Adds formatting, display, and
encryption information to the
packet.

9. Data-link Layer
Physical Layer
Transport Layer
Network Layer
Session Layer
Adds traffic flow
information to determine
when the packet gets
sent.
Adds error-handling
information
Sequencing and address
information is added to
the packet.
Adds error-checking
information and prepares
data for going on to the
physical connection.
Packet sent as a bit stream.
Protocol Stacks

10. Transport Protocols
Transport protocols facilitate communication sessions between
computers and ensure that data is able to move reliably
between computers. Popular transport protocols are shown in
theTable
Protocol Description
TCP The TCP/IP protocol for guaranteed delivery of sequenced data.
SPX Part of Novell's IPX/SPX protocol suite for sequenced data.
NWLink The Microsoft implementation of the IPX/SPX protocol.
NetBEUI (NetBIOS
extended user
interface)
Establishes communication sessions between computers (NetBIOS) and
provides the underlying data transport services (NetBEUI).
ATP (AppleTalk
Transaction Protocol)
and NBP (Name
Binding Protocol)
Apple's communication session and data transport protocols.

11. Network Protocols
Network protocols provide what are called "link services."
These protocols handle addressing and routing information,
error checking, and retransmission requests. Network
protocols also define rules for communicating in a particular
networking environment such as Ethernet or Token Ring.
Popular network protocols are shown in the Table
Protocol Description
IP The TCP/IP protocol for packet forwarding routing.
IPX NetWare's protocol for packet forwarding and routing.
NWLink The Microsoft implementation of the IPX/SPX protocol.
NetBEUI A transport protocol that provides data transport services for
NetBIOS sessions and applications.
DDP (Datagram
Delivery
Protocol)
An AppleTalk data transport protocol.

12. Implementing and Removing Protocols
Protocols are implemented and removed in much the same
way that drivers are added and removed. Essential protocols are
installed automatically at the same time the initial operating system is
installed on the computer. To install protocols such as NWLink after
the initial installation, the network operating system usually includes a
utility that leads the administrator through the process. For example, a
network operating system setup program might provide a series of
graphical windows that lead the administrator through the process of:
• Installing a new protocol.
• Changing the order in which the installed protocols have been
linked.
• Removing a protocol.

13. Lesson Summary:
The following points summarize the main elements of this lesson:
• Protocols in a networking environment define the rules and procedures for
transmitting data.
• To send data over a network successfully requires a series of separate steps
that must be carried out in a prescribed order.
• The sending and receiving computers use protocols to:
- Break data into packets.
- Add addressing information to the packets.
- Prepare the packets for transmission.
- Take the packets off the cable.
- Copy the data from the packets for reassembly.
- Pass the reassembled data to the computer.
• Several stacks are used as standard protocols; the most prominent standard
protocols are based on the OSI reference model layers.
• Protocols are implemented and removed in the same manner as drivers.

14. Thank
You Submitted by:
LANZ LOWEN JAY O. BOGNOT
9 - Pisces