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Network Protocols and Communications,Hierarchical Network Design Overview
Chapter 2
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Objectives
After completing this chapter, you will be able to:
Explain how rules are used to facilitate communication.
Explain the role of protocols and standards organizations in facilitating interoperability in network communications.
Explain how devices on a LAN access resources in a small to medium-sized business network.
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Chapter 2
2.1 Rules of Communication
2.2 Network Protocols and Standards
2.3 Moving Data in the Network
2.4 Hierarchical Network Design Overview
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Rules of Communication
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The Rules
What is Communication?
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The Rules
Establishing the Rules
An identified sender and receiver
Agreed upon method of communicating (face-to-face, telephone, letter, photograph)
Common language and grammar
Speed and timing of delivery
Confirmation or acknowledgment requirements
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The Rules
Message Encoding
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The Rules
Message Formatting and Encapsulation
Example: Personal letter contains the following elements:
Identifier of the recipient’s location
Identifier of the sender’s location
Salutation or greeting
Recipient identifier
The message content
Source identifier
End of message indicator
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The Rules
Message Size
An overview of the segmenting process:
The size restrictions of frames require the source host to break a long message into individual pieces (or segments) that meet both the minimum and maximum size requirements.
Each segment is encapsulated in a separate frame with the address information, and is sent over the network.
At the receiving host, the messages are de-encapsulated and put back together to be processed and interpreted.
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The Rules
Message Timing
Access Method
Flow Control
Response Timeout
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The Rules
Message Delivery Options
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Network Protocols and Standards
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Protocols
Rules that Govern Communications
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Protocols
Network Protocols
How the message is formatted or structured
The process by which networking devices share information about pathways with other networks
How and when error and system messages are passed between devices
The setup and termination of data transfer sessions
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Protocols
Interaction of Protocols
Application Protocol – Hypertext Transfer Protocol (HTTP)
Transport Protocol – Transmission Control Protocol (TCP)
Internet Protocol – Internet Protocol (IP)
Network Access Protocols – Data link & physical layers
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Protocol Suites
Protocol Suites and Industry Standards
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Protocol Suites
Creation of Internet, Development of TCP/IP
The first packet switching network and predecessor to today’s Internet was the Advanced Research Projects Agency Network (ARPANET), which came to life in 1969 by connecting mainframe computers at four locations.
ARPANET was funded by the U.S. Department of Defense for use by universities and research laboratories. Bolt, Beranek and Newman (BBN) was the contractor that did much of the initial development of the ARPANET, including creating the first router known as an Interface Message Processor (IMP).
In 1973, Robert Kahn and Vinton Cerf began work on TCP to develop the next generation of the ARPANET. TCP was designed to replace ARPANET’s current Network Control Program (NCP).
In 1978, TCP was divided into two protocols: TCP and IP. Later, other protocols were added to the TCP/IP suite of protocols including Telnet, FTP, DNS, and many others.
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Protocol Suites
TCP/IP Protocol Suite and Communication
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Standards Organizations
Open Standards
The Internet Society (ISOC)
The Internet Architecture Board (IAB)
The Internet Engineering Task Force (IETF)
Institute of Electrical and Electronics Engineers (IEEE)
The International Organization for Standards (ISO)
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Standards Organizations
ISOC, IAB, and IETF
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Standards Organizations
IEEE
38 societies
130 journals
1,300 conferences each year
1,300 standards and projects
400,000 members
160 countries
IEEE 802.3
IEEE 802.11
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Standards Organizations
ISO
OSI Model
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Standards Organizations
Other Standards Organization
The Electronic Industries Alliance (EIA)
The Telecommunications Industry Association (TIA)
The International Telecommunications Union – Telecommunications Standardization Sector (ITU-T)
The Internet Corporation for Assigned Names and Numbers (ICANN)
The Internet Assigned Numbers Authority (IANA)
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Reference Models
Benefits of Using a Layered Model
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Reference Models
The OSI Reference Model
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Reference Models
The TCP/IP Reference Model
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Reference Models
Comparing the OSI and TCP/IP Models
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Moving Data in the Network
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Data Encapsulation
Communicating the Messages
Segmenting message benefits
Different conversations can be interleaved
Increased reliability of network communications
Segmenting message disadvantage
Increased level of complexity
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Data Encapsulation
Protocol Data Units (PDUs)
Data
Segment
Packet
Frame
Bits
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Data Encapsulation
Protocol Encapsulation
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Data Encapsulation
Protocol De-encapsulation
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Moving Data in the Network
Accessing Local Resources
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Accessing Local Resources
Communicating with Device / Same Network
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Accessing Local Resources
MAC and IP Addresses
PC1192.168.1.110
AA-AA-AA-AA-AA-AA
PC2192.168.1.111
BB-BB-BB-BB-BB-BB
FTP Server192.168.1.9
CC-CC-CC-CC-CC-CC
R1192.168.1.1
11-11-11-11-11-11ARP
Request
S1 R1
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Accessing Remote Resources
Default Gateway
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Accessing Remote Resources
Communicating Device / Remote Network
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Hierarchical Network Design Overview
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Enterprise Network Campus Design
Network Requirements
Small network – Provides services for 1 to 200 devices.
Medium-sized network – Provides services for 200 to 1,000 devices.
Large network – Provides services for 1,000+ devices.
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Enterprise Network Campus Design
Structured Engineering Principles
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Hierarchical Network Design
Network Hierarchy
Access layer – Provides workgroup or user access to the network.
Distribution layer – Provides policy-based connectivity.
Core layer – Provides fast transport between distribution switches.
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Hierarchical Network Design
Access Layer Layer 2 switching
High availability
Port security
QoS classification and marking and trust boundaries
Address Resolution Protocol (ARP) inspection
Virtual access control lists (VACLs)
Spanning tree
Power over Ethernet (PoE) and auxiliary VLANs for VoIP
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Hierarchical Network Design
Distribution Layer
Aggregation of LAN or WAN links
Policy-based security in the form of access control lists (ACLs) and filtering
Routing services between LANs and VLANs and between routing domains (e.g., EIGRP to OSPF)
Redundancy and load balancing
A boundary for route aggregation and summarization configured on interfaces toward the core layer
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Hierarchical Network Design
Core Layer
Provides high-speed switching (i.e., fast transport)
Provides reliability and fault tolerance
Scales by using faster, and not more, equipment
Avoids CPU-intensive packet manipulation caused by security, inspection, quality of service (QoS) classification, or other processes
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Hierarchical Network Design
Two-Tier Collapsed Core Design
A two-tier hierarchical “collapsed core” is when the distribution layer and core layer functions are implemented by a single device.
Used by smaller businesses to reduce network cost while maintaining most of the benefits of the three-tier hierarchical model.
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Network Protocols and Communications
Summary
In this chapter, you learned:
Data networks are systems of end devices, intermediary devices, and the media connecting the devices. For communication to occur, these devices must know how to communicate.
These devices must comply with communication rules and protocols. TCP/IP is an example of a protocol suite.
Most protocols are created by a standards organization such as the IETF or IEEE.
The most widely-used networking models are the OSI and TCP/IP models.
Data that passes down the stack of the OSI model is segmented into pieces and encapsulated with addresses and other labels. The process is reversed as the pieces are de-encapsulated and passed up the destination protocol stack.
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Presentation_ID 47© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Network Protocols and Communications
Summary (cont.)
In this chapter, you learned:
The OSI model describes the processes of encoding, formatting, segmenting, and encapsulating data for transmission over the network.
The TCP/IP protocol suite is an open standard protocol that has been endorsed by the networking industry and ratified, or approved, by a standards organization.
The Internet Protocol Suite is a suite of protocols required for transmitting and receiving information using the Internet.
Protocol Data Units (PDUs) are named according to the protocols of the TCP/IP suite: data, segment, packet, frame, and bits.
Applying models allows individuals, companies, and trade associations to analyze current networks and plan the networks of the future.
Hierarchical Network Design Overview