Network+ Guide to Networks, 5 th Edition4 Troubleshooting
Methodology (contd.) Troubleshooting steps 1.Identify symptoms,
problems 2.Identify affected area 3.Determine what has changed
4.Establish most probable cause 5.Determine if escalation necessary
6.Create action plan, solution 7.Implement solution, test result
8.Identify results, effects 9.Document solution, process
Slide 4
Network+ Guide to Networks, 5 th Edition18 Hardware
Troubleshooting Tools Utilities help troubleshoot network problems
Specialized tools Crossover cable Butt Set Tone Generator
Multimeter Cable Continuity tester TDR OTDR
Slide 5
Software Tools Command line utilities IPCONFIG, Ping, TRACERT,
NetStat, NSLookup Network Monitor Network adapter must support
promiscuous mode Plug into port configured for port mirroring
Common terms for abnormal data patterns, packets Local collisions
Late collisions Runts Giants Jabber Ghosts
Slide 6
Software Tools Protocol Analyzer Captures traffic, analyzes
frames Sniffer (packet sniffer) hardware May require Port Mirroring
on switches to see all traffic. Only sees broadcasts and packets
directed to the analyzer.
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Question 1 When Jeff, a technician, is troubleshooting a
problem, which of the following is the NEXT step after verifying
full system functionality? A.Establish a plan of action to resolve
the problem and identify potential effects. B.Implement the
solution. C.Establish a theory of probable cause. D.Document
findings, actions, and outcomes
Slide 8
Question 2 Kim, a network technician, is troubleshooting a
problem and has just established a plan of action to resolve the
problem. Which of the following is the NEXT step in the
troubleshooting methodology? A. Verify full system functionality
and if applicable implement preventative measures. B.Implement the
solution or escalate as necessary. C.Document findings, actions,
and outcomes. D.Establish a theory of probable cause (e.g. question
the obvious).
Slide 9
Question 3 Lisa, a technician, is troubleshooting a cable
problem. She has checked both ends and suspects an issue 50 yards
(46 meters) from the location. Which of the following network tools
will confirm this analysis? A.TDR B.Protocol analyzer C.Multimeter
D.Cable crimper
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Question 4 A switch in IDF 3 has shut down at 3 p.m. everyday
this week. Which of the following network tools should Kim, a
technician, use to troubleshoot this problem? Environmental monitor
Cable Tester TDR Loopback plug
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Question 5 Which of the following tools would Lisa, a
technician, BEST use to trace a wire through an area where multiple
wires of the same color are twisted together? A.Cable tester
B.Toner probe C.Cable crimper D.Punch down tool
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Question 6 Zach, a technician, wants to test a laptop's NIC for
functionality but has no other networking equipment to attach it
to. Which of the following would allow him to test basic
functionality of the NIC? A.Loopback plug B.Protocol analyzer
C.Smart jack D.Coupler
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Question 7 Lisa, a network technician, is troubleshooting a new
wireless network that has been dropping connections. She notices
another wireless network in the area. Which of the following BEST
explains the reason for the dropped connections? A. Latency B. SSID
mismatch C. Interference D. Encryption type
Slide 14
Question 8 Zach, a technician, suspects a duplicate IP address
assignment on the network. Which of the following resources can be
used to verify this problem? A. Network map B. Environmental
monitor C. Placement map D. Syslog
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Question 9 Zach, a technician, discovers a switch is not
communicating with the other switches in a stack. Which of the
following is the MOST likely cause? A.Both T568A and T568B
standards are being used. B.STP is disabled. C.The cable is not a
crossover. D.The port is not trunked.
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Question 10 Kim, a network consultant, noticed that a new
installation for a network backbone looked like this: ISP - Switch
- Firewall - PC. Which of the following is the BEST configuration
for a properly setup environment? A.Switch - ISP - Firewall PC
B.ISP - Firewall - Switch - PC C.Firewall - ISP - PC - Switch D.ISP
- PC - Firewall - Switch
Slide 17
VOIP Components
Slide 18
Network+ Guide to Networks, 5 th Edition14 Analog Telephone
Attachment Figure 11-4 Integrating VoIP networks and analog
telephones
Slide 19
Network+ Guide to Networks, 5 th Edition15 Digital - IP
Telephones IP telephones (IP phones) Transmit, receive only digital
signals Voice immediately digitized, issued to network in packet
form Requires unique IP address Looks like traditional touch-tone
phone Connects to RJ-45 wall jack Connection may pass through
connectivity device before reaching IP-PBX
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Softphones Computer programmed to act like IP telephone
Softphones and IP telephones Provide same calling functions Connect
to network; deliver services differently Prerequisites Computer
minimum hardware requirements IP telephony client installed Digital
telephone switch communication Full-duplex sound card Microphone,
speakers Example: Skype Network+ Guide to Networks, 5 th
Edition20
Slide 21
Network+ Guide to Networks, 5 th Edition23 Figure 11-8
Connecting softphones to a converged network
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Network+ Guide to Networks, 5 th Edition37 Signaling Protocols
Signaling Establish connection Information exchange Between network
components, system Establishing, monitoring, releasing connections
Controlling system operations SS7 Protocol for handling call
signaling in PSTN connections H.323 and SIP for VOIP
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38 H.323 Supports voice, video-over-IP services H.323
components H.323 terminal H.323 gateway H.323 gatekeeper MCU
(multipoint control unit) H.323 zone H.323 Protocols H.225
Application layer used for call setup signaling H.245
Session/presentation layer formatting Logical channels identified
as port numbers One channel for each direction (full duplex)
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Network+ Guide to Networks, 5 th Edition42 SIP (Session
Initiation Protocol) Performs similar H.323 functions Version 2.0
(RFC 2543) 1999 IETF codified Application layer signaling,
multiservice control protocol, packet-based networks Goals Modeled
on HTTP protocol Reuse existing TCP/IP protocols Session
management, enhanced services Modular and specific
Slide 25
Network+ Guide to Networks, 5 th Edition43 SIP (contd.) Similar
purpose to H.323 More Limited capabilities and functions Does not
supply caller ID SIP network Modeled on HTTP Standard maps out
terms and architecture User agent User agent client User agent
server Registrar server Proxy server Redirect server
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Network+ Guide to Networks, 5 th Edition44 SIP (contd.) Figure
11-14 A SIP network
Slide 27
Network+ Guide to Networks, 5 th Edition45 SIP vs H.323 SIP and
H.323 Regulate call signaling, control for VoIP or video-over- IP
clients and servers Do not account for communication between media
gateways VoIP vendors prefer SIP over H.323 Simplicity Fewer
instructions to control call Consumes fewer processing resources
Adapts easier More flexible
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46 Media Gateways Gateways Enable converged networks Convert
analog to digital signals Translate between SS7 and H.323/SIP MGCP
(Media Gateway Control Protocol) MEGACO Performs same functions as
MGCP with different commands and processes Operates with H.323 or
SIP Superior to MGCP Supports ATM
Slide 29
Network+ Guide to Networks, 5 th Edition48 MGCP and MEGACO
(contd.) Figure 11-15 Use of an MGC (media gateway controller)
Slide 30
Transport Protocols Used to deliver voice or video payload
Typically use UDP because less overhead Require some additional
delivery feedback information and method to provide for Quality of
Service (QoS) in Delivery Delivery Feedback Protocols RTP RTCP QoS
Proocols RSVP DiffServ MPLS
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Network+ Guide to Networks, 5 th Edition51 RTP (Real-time
Transport Protocol) RFC 1889 Operates at Application layer Relies
on UDP Applies sequence numbers to indicate: Destination packet
assembly order Packet loss during transmission Assigns packet
timestamp Receiving node Compensates for network delay, synchronize
signals No mechanism to detect success
Slide 32
RTCP (Real-time Transport Control Protocol) Provides quality
feedback to participants Packets transmitted periodically Works
with RTP Not mandatory on RTP networks RTP and RTCP Provide
information about packet order, loss, delay Cannot correct
transmission flaws 52
Slide 33
53 QoS (Quality of Service) Assurance Protocols used to improve
the packet switched VOIP or Video connection to make it more like a
dedicated PSTN or Cable network. QoS measures how well a service
matches its expected performance. High Does not experience
interruptions, distortions, or broken communications Low May
experience communication problems QoS protocols RSVP DiffServ
MPLS
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54 RSVP (Resource Reservation Protocol) Transport layer
protocol Reserves network resources before transmission by creating
path between sender, receiver Issues PATH statement via RSVP to
receiving node Two service types Guaranteed service No packet
losses minimal delay Controlled-load service Type of service
typical on low usage network
Slide 35
Network+ Guide to Networks, 5 th Edition57 DiffServ Addresses
traffic prioritization QoS issues Differs from RSVP Modifies actual
IP datagram Accounts for all network traffic To prioritize traffic
IPv4 datagram: DiffServ field IPv6 datagram: Traffic Class
field
Slide 36
58 DiffServ (contd.) Two forwarding types EF (Expedited
Forwarding) Data stream assigned minimum departure rate Circumvents
delays by setting strict limits max 30 % of traffic AF (Assured
Forwarding) Data streams assigned different router resource levels
Prioritizes data handling but provides not guarantee of On time, in
sequence packet arrival Uses AF Classes to provide different
service levels
Slide 37
Network+ Guide to Networks, 5 th Edition59 MPLS (Multiprotocol
Label Switching) Modifies data streams at Network layer A first
router data stream encounters Replaces IP datagram header with
label Packet forwarding information Routers data stream path
revises label Indicates next hop Considers network congestion Very
fast forwarding: no delay Destination IP address compared to
routing tables Forward data to closest matching node