© 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 1 Chapter 3: Network Protocols and Communications Introduction to Networks

Presentation_ID 2 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Chapter Rules of Communication 3.2 Network Protocols and Standards 3.3 Moving Data in the Network 3.4 Summary

Presentation_ID 3 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential The Rules What is Communication? 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 acknowledgement requirements

Presentation_ID 4 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Protocol’s duty

Presentation_ID 5 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential The Rules Message Encoding

Presentation_ID 6 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential The Rules Message Formatting and Encapsulation

Presentation_ID 7 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential The Rules Message Size  Segmenting MSS – maximum segment size  Multiplexing

Presentation_ID 8 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential The Rules Message Timing  Access Method Full duplex Half duplex  Flow Control  Response Timeout

Presentation_ID 9 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential The Rules Message Delivery Options

Presentation_ID 10 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Protocols Rules that Govern Communications

Presentation_ID 11 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential 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

Presentation_ID 12 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Protocols Interaction of Protocols

Presentation_ID 13 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Protocol Suites Protocol Suites and Industry Standards

Presentation_ID 14 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Protocol Suites Creation of Internet, Development of TCP/IP )/course/module3/index.html#

Presentation_ID 15 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Protocol Suites TCP/IP Protocol Suite and Communication ing)/course/module3/index.html#

Presentation_ID 16 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Exercise  )/course/module3/index.html# )/course/module3/index.html#

Presentation_ID 17 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Network Protocols and Standards Standards Organizations 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)

Presentation_ID 18 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Standards Organizations ISOC, IAB, and IETF

Presentation_ID 19 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Standards Organizations IEEE  38 societies  130 journals  1,300 conferences each year  1,300 standards and projects  400,000 members  160 countries

Presentation_ID 20 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Standards Organizations ISO

Presentation_ID 21 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Standards Organizations Other Standards Organization  The Electronic Industries Alliance (EIA) – 19 inch racks standarts  The Telecommunications Industry Association (TIA)- The International Telecommunications Union – VoIP, satellite  Telecommunications Standardization Sector (ITU-T) - IPTV, DSL  The Internet Corporation for Assigned Names and Numbers (ICANN)-  The Internet Assigned Numbers Authority (IANA) DNS IP AS number

Presentation_ID 22 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Reference Models The Benefits of Using a Layered Model

Presentation_ID 23 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Reference Models The OSI Reference Model

Presentation_ID 24 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Reference Models The TCP/IP Protocol Model

Presentation_ID 25 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Reference Models Comparing the OSI and TCP/IP Models x.html#

Presentation_ID 26 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential 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

Presentation_ID 27 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Data Encapsulation Protocol Data Units (PDUs)  Data  Segment  Packet  Frame  Bits

Presentation_ID 28 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Data Encapsulation Encapsulation

Presentation_ID 29 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Data Encapsulation De-encapsulation course/module3/index.html#

Presentation_ID 30 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Moving Data in the Network Accessing Local Resources

Presentation_ID 31 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Accessing Local Resources Communicating with Device / Same Network

Presentation_ID 32 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Accessing Local Resources MAC and IP Addresses PC AA-AA-AA-AA-AA-AA PC BB-BB-BB-BB-BB-BB FTP Server CC-CC-CC-CC-CC-CC R ARP Request S1R1

Presentation_ID 33 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Accessing Remote Resources Default Gateway PC AA-AA-AA-AA-AA-AA PC BB-BB-BB-BB-BB-BB FTP Server CC-CC-CC-CC-CC-CC R R Web Server AB-CD-EF

Presentation_ID 34 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Accessing Remote Resources Communicating Device / Remote Network

Presentation_ID 35 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Accessing Remote Resources Using Wireshark to View Network Traffic ab%20-%20Using%20Wireshark%20to%20View%20Network%20Traffic.pdf

Presentation_ID 36 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Password phrase “My favorite spy is James Bond 007.” = MfsiJB007. “It was the best of times, it was the worst of times.”= Iwtbotiwtwot. “Fly me to the moon. And let me play among the stars.” = FmttmAlmpats  To increase the security of passwords, the following Cisco IOS commands should be utilized: Enforce minimum password length: security passwords min- length. Disable unattended connections: exec-timeout. Encrypt config file passwords: service password-encryption.

Presentation_ID 37 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Enforce Minimum Password Lengths  Make passwords lengthy. IOS 12.3 and later passwords can be 0 to 16 characters in length. The best practice is to have a minimum of 10 characters.  To enforce the minimum length use the global command: security passwords min-length length  The command affects all “new” router passwords. Existing router passwords are unaffected.  Any attempt to create a new password that is less than the specified length fails and results in an “Password too short” error message.

Presentation_ID 38 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential  By default, an administrative interface stays active and logged in for 10 minutes after the last session activity. After that, the interface times out and logs out of the session.  The timer can be adjusted using the exec-timeout command in line configuration mode for each of the line types that are used. exec-timeout minutes seconds Note: exec-timeout 0 0 means that there will be no timeout and the session will stay active for an unlimited time. Great for Labs … Bad in production networks! Never set the value to 0! Disable Unattended Connections

Presentation_ID 39 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential  Default time is 10 minutes.  Terminates an unattended connection (console or vty).  Provides additional level of security if an administrator walks away from an active console session. To terminate an unattended console connection after 3 minutes and 30 seconds: To disable the exec process on the line: Disable Unattended Connections Router(config-line)# exec-timeout minutes [seconds] Sudbury(config)# line console 0 Sudbury(config-line)# exec-timeout 3 30 Sudbury(config)# line aux 0 Sudbury(config-line)# no exec-timeout

Presentation_ID 40 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Encrypt all passwords in the router configuration file. Encrypt All Passwords service password-encryption Router(config)# R1(config)# service password-encryption R1(config)# exit R1# show running-config enable password A061E ! line con 0 password 7 094F471A1A0A login ! line aux 0 password F D72 login line vty 0 4 password A0F034F38435B49150A1819 login

Presentation_ID 41 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential  Secure the local database passwords. Traditional user configuration with plaintext password. Use MD5 hashing for strong password protection. More secure than the type 7 encryption. Securing Local Database Passwords username name secret {[0] password | encrypted-secret} username name password {[0] password | 7 hidden-password}

Presentation_ID 42 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential 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.

Presentation_ID 43 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Network Protocols and Communications Summary In this chapter, you learned:  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.  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.

Presentation_ID 44 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential Network Protocols and Communications Summary In this chapter, you learned:  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.

Presentation_ID 45 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential