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Network Plus Troubleshooting and VOIP

Network Plus Troubleshooting and VOIP. 1/28/2010. 1/28/2010. Troubleshooting Methodology (cont’d.). Troubleshooting steps Identify symptoms, problems Identify affected area Determine what has changed Establish most probable cause Determine if escalation necessary

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Network Plus Troubleshooting and VOIP

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  1. Network PlusTroubleshooting and VOIP 1/28/2010 1/28/2010

  2. Troubleshooting Methodology (cont’d.) Troubleshooting steps Identify symptoms, problems Identify affected area Determine what has changed Establish most probable cause Determine if escalation necessary Create action plan, solution Implement solution, test result Identify results, effects Document solution, process Network+ Guide to Networks, 5th Edition 4

  3. Hardware Troubleshooting Tools Utilities help troubleshoot network problems Specialized tools Crossover cable Butt Set Tone Generator Multimeter Cable Continuity tester TDR OTDR Network+ Guide to Networks, 5th Edition 18

  4. 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

  5. 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.

  6. 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

  7. 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).

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.Thecable is not a crossover. • D.Theport is not trunked.

  15. 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

  16. VOIP Components

  17. Analog Telephone Attachment Figure 11-4 Integrating VoIP networks and analog telephones Network+ Guide to Networks, 5th Edition 14

  18. 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 Network+ Guide to Networks, 5th Edition 15

  19. 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, 5th Edition 20

  20. Figure 11-8 Connecting softphones to a converged network Network+ Guide to Networks, 5th Edition 23

  21. 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 Network+ Guide to Networks, 5th Edition 37

  22. 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) 38

  23. 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 Network+ Guide to Networks, 5th Edition 42

  24. SIP (cont’d.) 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 Network+ Guide to Networks, 5th Edition 43

  25. SIP (cont’d.) Figure 11-14 A SIP network Network+ Guide to Networks, 5th Edition 44

  26. 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 Network+ Guide to Networks, 5th Edition 45

  27. 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 46

  28. MGCP and MEGACO (cont’d.) Figure 11-15 Use of an MGC (media gateway controller) Network+ Guide to Networks, 5th Edition 48

  29. 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 • QoSProocols • RSVP • DiffServ • MPLS

  30. 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 Network+ Guide to Networks, 5th Edition 51

  31. 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

  32. 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 53

  33. 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 54

  34. 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 Network+ Guide to Networks, 5th Edition 57

  35. DiffServ (cont’d.) 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 58

  36. 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 Router’s 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 Network+ Guide to Networks, 5th Edition 59

  37. The End Network+ Guide to Networks, 5th Edition Network+ Guide to Networks, 5th Edition

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