Download Chapter 3 - TCP/IP Standards

Figure 3-2: TCP/IP Standards (Study
Figure)

Origins

Defense Advanced Research Projects Agency
(DARPA) created the ARPANET

An internet connects multiple individual networks

Global Internet is capitalized

Internet Engineering Task Force (IETF)

Most IETF documents are requests for
comments (RFCs)

Internet Official Protocol Standards: List of RFCs
that are official standards
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Figure 3-2: TCP/IP Standards (Study
Figure)

Hybrid TCP/IP-OSI Architecture (Figure 3-3)


Combines TCP/IP standards at layers 3-5 with
OSI standards at layers 1-2
TCP/IP
Application
OSI
Application
Hybrid TCP/IP-OSI
Application
Presentation
Session
Transport
Transport
Transport
Internet
Network
Internet
Subnet Access: Use
OSI Standards Here
Data Link
Data Link
Physical
Physical
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Figure 3-2: TCP/IP Standards (Study
Figure)

OSI Layers

Physical (Layer 1): defines electrical signaling
and media between adjacent devices

Data link (Layer 2): control of a frame through a
single network, across multiple switches
Physical Link
Frame
Switched
Network 1
Data Link
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Figure 3-2: TCP/IP Standards

Internet Layer

Governs the transmission of a packet across an
entire internet. Path of the packet is its route
Packet
Switched
Network 1
Route
Switched Network 3
Router
Switched
Network 2
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Figure 3-2: TCP/IP Standards (Study
Figure)

Frames and Packets

Frames are messages at the data link layer

Packets are messages at the internet layer

Packets are carried (encapsulated) in frames

There is only a single packet that is delivered
from source to destination host

This packet is carried in a separate frame in
each network
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Figure 3-2: TCP/IP Standards (Study
Figure)

Internet and Transport Layers

Purposes

Internet layer governs hop-by-hop transmission
between routers to achieve end-to-end delivery
Transport layer is end-to-end (host-to-host) protocol
involving only the two hosts
Internet Protocol (IP)



IP at the internet layer is unreliable—does not correct
errors in each hop between routers

This is good: reduces the work each router along the
route must do
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Figure 3-2: TCP/IP Standards (Study
Figure)

Transport Layer Standards

Transmission Control Protocol (TCP)
 Reliable and connection-oriented service at
the transport layer
 Corrects errors

User Datagram Protocol (UDP)
 Unreliable and connectionless service at the
transport layer
 Lightweight protocol good when catching
errors is not important
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Figure 3-7: Internet and Transport Layers
Transport Layer
End-to-End (Host-to-Host)
TCP is Connection-Oriented, Reliable
UDP is Connectionless Unreliable
Client PC
Server
Internet Layer
(Usually IP)
Hop-by-Hop (Host-Router or Router-Router)
Connectionless, Unreliable
Router 1
Router 2
Router 3
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Figure 3-2: TCP/IP Standards (Study
Figure)

Application Layer

To govern communication between application
programs, which may be written by different
vendors

Document transfer versus document format
standards
 HTTP / HTML for WWW service
 SMTP / RFC 822 (or RFC 2822) in e-mail

Many application standards exist because there
are many applications
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Figure 3-8: HTML and HTTP at the
Application Layer
Hypertext Transfer Protocol (HTTP)
Requests and Responses
Webserver
Client PC with
Browser
123.34.150.37
60.168.47.47
Hypertext Markup Language (HTML)
Document or Other File (jpeg, etc.)
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Figure 3-3: TCP/IP and OSI
Architectures: Recap
TCP/IP
Application
OSI
Application
Hybrid TCP/IP-OSI
Application
Presentation
Session
Transport
Transport
Transport
Internet
Network
Internet
Subnet Access: Use
OSI Standards Here
Data Link
Data Link
Physical
Physical
Note: The Hybrid TCP/IP-OSI Architecture is used on the Internet and
dominates internal corporate networks.
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