One of your objectives thus far is for you to shoot trouble rather than let trouble shoot you.
When confronted with network problems, it is of utmost importance for you to define the problem, gather facts, and consider various possibilities based on those facts. The connection may not be possible, for example, or perhaps the data transfer is just slow. Higher-level processes may provide error-checking issues, retransmission problems, routed and routing protocol issues, and other problems. Lower-level data-link targets are basically interfaces and controllers. This chapter reviews the output of some basic IOS commands to assist you in identifying trouble-shooting targets and to prove this bottom-up troubleshooting theory before you adventure into the detailed troubleshooting Trouble Ticket-based chapters to follow.
This chapter focuses on many of the CCNP Troubleshooting objectives and is just as critical to your overall certification and practical success as the preceding chapter. This chapter specifically addresses what you need in your tool bag for Cisco troubleshooting. The chapter starts by
reviewing IOS commands and goes on to discuss other hardware- and software-related tools you need in your bag.
This chapter covers the following topics:
IOS Troubleshooting Tools Cisco Connection Online Project DOTU
Network Management
Hardware Tools and Media Testers Network Monitors
Protocol Analyzers Desktop Tools
Supporting Website Files
You can find files and links to utilities that support this book on the Cisco Press website at www.ciscopress.com/1587200570. Even if you do not have a lab, you can take advantage of the supporting configuration files including the logs to understand device input and output. The files are listed throughout the chapters in italics.
In order to be able to read and work with some of the supporting files offered at www.ciscopress.com/1587200570, you may want to download some of the programs listed in Table I-1 in the Introduction.
• Table of Contents
• Index
CCNP Practical Studies: Troubleshooting By Donna L. Harrington
Publisher: Cisco Press Pub Date: April 04, 2003
ISBN: 1-58720-057-0 Pages: 840
Hands-on practice for the CCNP Troubleshooting exam with TCP/IP, LAN, and WAN trouble tickets based on Cisco Internetwork Troubleshooting (CIT) topics.
With this book, you can:
Set up and follow along with real-world lab scenarios aligned to each exam topic, with or without the actual equipment
Establish a baseline and document your physical and logical network
Identify troubleshooting targets using ping, trace, show, clear, debug, and other troubleshooting tools and utilities
Diagnose and troubleshoot actual problems by following along with author-provided Catalyst(r) OS and Cisco IOS(r) Software command input, output, and logging Use instructor-developed problem-isolation methods to resolve Trouble Tickets
"Sniff" the wire to spot network issues
Analyze local and remote access problems in Ethernet networks, including issues with cabling, speed and duplex, utilization and collisions, bandwidth, CSMA/CD, one-way link, auto negotiation, addressing, encapsulation, and more
Apply a layered troubleshooting methodology to real-life routing and switching environments
Designed for aspiring CCNP and CCIE(r) professionals, this indispensable lab guide builds on Cisco(r) Internetwork Troubleshooting (CIT) topics that prepare you for the CCNP
Troubleshooting exam. Full of practical exercises that get you ready for challenges on the job, CCNP Practical Studies: Troubleshooting gives you an edge over the competition through real- world application of LAN and WAN topics.
CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including
IOS Troubleshooting Tools
Cisco is more than just a hardware company. Cisco IOS provides you with powerful diagnostic programs such as show, ping, trace, log, and debug commands. Mastering them is important because some of these can be simple tools that can still save you a great deal of time.
Table 2-1 and the following sections review some basic IOS troubleshooting tools. The objectives here are to review the output and summarize the importance of the commands so that you can put them to practical use. Many times it is advantageous if you can physically inspect the hardware, such as the equipment, cables, and connectors; but maybe you can't. Lots of times you are remote to the problem, depending on your scenario, so it is critical to know the tools innate to the IOS to assist you.
NOTE
Review Chapter 1, "Shooting Trouble," to make sure you have an understanding of protocol technical characteristics and a systematic method for troubleshooting.
Table 2-1. IOS Troubleshooting Tools
Cisco Command
Description
show A snapshot of what is occurring to monitor status. The show commands enable you to detect neighbors, spot performance issues, and isolate problems.
ping Determine end-to-end connectivity and reachability.
traceroute Hop-by-hop approach to finding the problem.
log Monitor and view messages that record real-time events, such as errors, warnings, and state transitions.
debug Use for troubleshooting traffic flow or misconfigurations; not for normal daily operations.
Cisco Show Commands
Cisco show commands give a snapshot of what is occurring to monitor status, detect neighbors, spot performance issues, and isolate problems. This discussion covers several show commands to prepare you for the chapter practical exercise, various Trouble Tickets throughout the book, and for your overall real-world troubleshooting needs. Feel free to use the question mark (?) for help or more detail. Be aware that show ? yields different results according to whether you are in user mode or privileged (enable) mode. In addition, you can use show cdp ? to display the optional keywords available with that particular command.
• Table of Contents
• Index
CCNP Practical Studies: Troubleshooting By Donna L. Harrington
Publisher: Cisco Press Pub Date: April 04, 2003
ISBN: 1-58720-057-0 Pages: 840
Hands-on practice for the CCNP Troubleshooting exam with TCP/IP, LAN, and WAN trouble tickets based on Cisco Internetwork Troubleshooting (CIT) topics.
With this book, you can:
Set up and follow along with real-world lab scenarios aligned to each exam topic, with or without the actual equipment
Establish a baseline and document your physical and logical network
Identify troubleshooting targets using ping, trace, show, clear, debug, and other troubleshooting tools and utilities
Diagnose and troubleshoot actual problems by following along with author-provided Catalyst(r) OS and Cisco IOS(r) Software command input, output, and logging Use instructor-developed problem-isolation methods to resolve Trouble Tickets
"Sniff" the wire to spot network issues
Analyze local and remote access problems in Ethernet networks, including issues with cabling, speed and duplex, utilization and collisions, bandwidth, CSMA/CD, one-way link, auto negotiation, addressing, encapsulation, and more
Apply a layered troubleshooting methodology to real-life routing and switching environments
Designed for aspiring CCNP and CCIE(r) professionals, this indispensable lab guide builds on Cisco(r) Internetwork Troubleshooting (CIT) topics that prepare you for the CCNP
Troubleshooting exam. Full of practical exercises that get you ready for challenges on the job, CCNP Practical Studies: Troubleshooting gives you an edge over the competition through real- world application of LAN and WAN topics.
CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including
NOTE
The following examples and screen shots were captured with little or no traffic, but are some of the commands you should use to set up a baseline. Any time you see ... I have cut part of the output.
Use show controllers for Ethernet, Token Ring, FDDI, or T1 to see DTE/DCE, clocking, bandwidth, and to determine whether the cable is plugged in properly. Narrow the command output by
specifying an interface, such as s0. Remember, however, to put a space between the s and the 0.
This is the only IOS command I can think of where you must put the space (but, in fact, this is an IOS release-dependent behavior). Examples 2-1 through 2-3 show the output of show controllers serial 0.
Example 2-1. show controllers on DCE End with serial 0 Up and Running
r2>show controllers serial 0
HD unit 0, idb = 0xDFE7C, driver structure at 0xE52F8
buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 64000 ...
The shaded line emphasizes the V.35 DCE cable with a clock rate of 64000. The DCE end of a serial line always provides clocking (timing synchronization). Normally you receive the clock from the service provider, but in a lab scenario a back-to-back 60-pin serial cable is used (in which the DCE end requires the clock rate command). You can order these cables for your lab from such places as Ebay.com or Stonewallcable.com. Search for "cable assemblies and pinouts" on Cisco.com for a picture of the DB60 60-pin, male, back-to-back EIA-530 type used for the practical examples in this book.
Example 2-2 shows what happens when you unplug the cable. If you can, set up two routers of your own with the back-to-back serial cable and give it a try.
Example 2-2. show controllers and show interfaces with serial 0 Unplugged
r2#
00:59:36: %LINK-3-UPDOWN: Interface Serial0, changed state to down
00:59:37: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state
• Table of Contents
• Index
CCNP Practical Studies: Troubleshooting By Donna L. Harrington
Publisher: Cisco Press Pub Date: April 04, 2003
ISBN: 1-58720-057-0 Pages: 840
Hands-on practice for the CCNP Troubleshooting exam with TCP/IP, LAN, and WAN trouble tickets based on Cisco Internetwork Troubleshooting (CIT) topics.
With this book, you can:
Set up and follow along with real-world lab scenarios aligned to each exam topic, with or without the actual equipment
Establish a baseline and document your physical and logical network
Identify troubleshooting targets using ping, trace, show, clear, debug, and other troubleshooting tools and utilities
Diagnose and troubleshoot actual problems by following along with author-provided Catalyst(r) OS and Cisco IOS(r) Software command input, output, and logging Use instructor-developed problem-isolation methods to resolve Trouble Tickets
"Sniff" the wire to spot network issues
Analyze local and remote access problems in Ethernet networks, including issues with cabling, speed and duplex, utilization and collisions, bandwidth, CSMA/CD, one-way link, auto negotiation, addressing, encapsulation, and more
Apply a layered troubleshooting methodology to real-life routing and switching environments
Designed for aspiring CCNP and CCIE(r) professionals, this indispensable lab guide builds on Cisco(r) Internetwork Troubleshooting (CIT) topics that prepare you for the CCNP
Troubleshooting exam. Full of practical exercises that get you ready for challenges on the job, CCNP Practical Studies: Troubleshooting gives you an edge over the competition through real- world application of LAN and WAN topics.
CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including to down
r2#show controllers serial 0
HD unit 0, idb = 0xDFE7C, driver structure at 0xE52F8 buffer size 1524 HD unit 0, No cable, clockrate 64000 ...
r2#show interfaces serial 0
Serial0 is down, line protocol is down Hardware is HD64570
Description: r2 s0 DCE to r1 s0 DTE Internet address is 192.168.2.2/24
MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:03:31, output 00:03:35, output hang never Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/2/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec 390 packets input, 22659 bytes, 0 no buffer
Received 367 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 389 packets output, 23296 bytes, 0 underruns
0 output errors, 0 collisions, 26 interface resets 0 output buffer failures, 0 output buffers swapped out 7 carrier transitions
• Table of Contents
• Index
CCNP Practical Studies: Troubleshooting By Donna L. Harrington
Publisher: Cisco Press Pub Date: April 04, 2003
ISBN: 1-58720-057-0 Pages: 840
Hands-on practice for the CCNP Troubleshooting exam with TCP/IP, LAN, and WAN trouble tickets based on Cisco Internetwork Troubleshooting (CIT) topics.
With this book, you can:
Set up and follow along with real-world lab scenarios aligned to each exam topic, with or without the actual equipment
Establish a baseline and document your physical and logical network
Identify troubleshooting targets using ping, trace, show, clear, debug, and other troubleshooting tools and utilities
Diagnose and troubleshoot actual problems by following along with author-provided Catalyst(r) OS and Cisco IOS(r) Software command input, output, and logging Use instructor-developed problem-isolation methods to resolve Trouble Tickets
"Sniff" the wire to spot network issues
Analyze local and remote access problems in Ethernet networks, including issues with cabling, speed and duplex, utilization and collisions, bandwidth, CSMA/CD, one-way link, auto negotiation, addressing, encapsulation, and more
Apply a layered troubleshooting methodology to real-life routing and switching environments
Designed for aspiring CCNP and CCIE(r) professionals, this indispensable lab guide builds on Cisco(r) Internetwork Troubleshooting (CIT) topics that prepare you for the CCNP
Troubleshooting exam. Full of practical exercises that get you ready for challenges on the job, CCNP Practical Studies: Troubleshooting gives you an edge over the competition through real- world application of LAN and WAN topics.
CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including DCD=down DSR=down DTR=down RTS=down CTS=down
r2#
01:06:38: %LINK-3-UPDOWN: Interface Serial0, changed state to up
01:06:39: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to up
...
The show controllers output "no cable" on r2 indicates that the cable is unplugged. Hence, the status of serial0 in Example 2-2 is that s0 is down and the line protocol is down. Notice the last couple of lines of the display for show interfaces serial0. These indicate carrier transitions; all modem control leads are down, too. This is obviously a Layer 1 issue. Now plug the cable back in and take a look at the DTE end on r1 in Example 2-3.
Example 2-3. show controllers on DTE End with serial 0 Up and Running
r1>show controllers serial 0
HD unit 0, idb = 0xFC1A8, driver structure at 0x101628 buffer size 1524 HD unit 0, V.35 DTE cable
cpb = 0xE2, eda = 0x4064, cda = 0x4078 RX ring with 16 entries at 0xE24000
00 bd_ptr=0x4000 pak=0x104A60 ds=0xE2F240 status=80 pak_size=45 01 bd_ptr=0x4014 pak=0x103E60 ds=0xE2C9D8 status=80 pak_size=45 r1>
It is often difficult to discuss one IOS command without mentioning another. For example, it is almost impossible to discuss the show controllers command without mentioning the show interfaces command because they are both very important lower-level troubleshooting target commands.
The show interfaces command shows the statistics for all the Ethernet, Token Ring, FDDI, ATM, BRI, PRI, High-Speed Serial Interface (HSSI), or serial interfaces on a particular box. However, it is normally more helpful to clear the counters and look at just a particular interface to hone in on the problem. The clear counters command resets the counters, enabling you to look at the interface from a certain time forward; however, it does not reset things such as Simple Network Management Protocol (SNMP) parameters. Example 2-4 illustrates these interface commands.
• Table of Contents
• Index
CCNP Practical Studies: Troubleshooting By Donna L. Harrington
Publisher: Cisco Press Pub Date: April 04, 2003
ISBN: 1-58720-057-0 Pages: 840
Hands-on practice for the CCNP Troubleshooting exam with TCP/IP, LAN, and WAN trouble tickets based on Cisco Internetwork Troubleshooting (CIT) topics.
With this book, you can:
Set up and follow along with real-world lab scenarios aligned to each exam topic, with or without the actual equipment
Establish a baseline and document your physical and logical network
Identify troubleshooting targets using ping, trace, show, clear, debug, and other troubleshooting tools and utilities
Diagnose and troubleshoot actual problems by following along with author-provided Catalyst(r) OS and Cisco IOS(r) Software command input, output, and logging Use instructor-developed problem-isolation methods to resolve Trouble Tickets
"Sniff" the wire to spot network issues
Analyze local and remote access problems in Ethernet networks, including issues with cabling, speed and duplex, utilization and collisions, bandwidth, CSMA/CD, one-way link, auto negotiation, addressing, encapsulation, and more
Apply a layered troubleshooting methodology to real-life routing and switching environments
Designed for aspiring CCNP and CCIE(r) professionals, this indispensable lab guide builds on Cisco(r) Internetwork Troubleshooting (CIT) topics that prepare you for the CCNP
Troubleshooting exam. Full of practical exercises that get you ready for challenges on the job, CCNP Practical Studies: Troubleshooting gives you an edge over the competition through real- world application of LAN and WAN topics.
CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including
Example 2-4. show interfaces and clear counters
r2>show interfaces
Ethernet0 is up, line protocol is up
Hardware is Lance, address is 0000.0c38.a05d (bia 0000.0c38.a05d) Description: r2 e0 to HostC Win98Dell
Internet address is 192.168.3.1/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255 Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:04:22, output 00:00:03, output hang never Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec 15 packets input, 3026 bytes, 0 no buffer
Received 10 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected
554 packets output, 55751 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out Serial0 is up, line protocol is up
...
• Table of Contents
• Index
CCNP Practical Studies: Troubleshooting By Donna L. Harrington
Publisher: Cisco Press Pub Date: April 04, 2003
ISBN: 1-58720-057-0 Pages: 840
Hands-on practice for the CCNP Troubleshooting exam with TCP/IP, LAN, and WAN trouble tickets based on Cisco Internetwork Troubleshooting (CIT) topics.
With this book, you can:
Set up and follow along with real-world lab scenarios aligned to each exam topic, with or without the actual equipment
Establish a baseline and document your physical and logical network
Identify troubleshooting targets using ping, trace, show, clear, debug, and other troubleshooting tools and utilities
Diagnose and troubleshoot actual problems by following along with author-provided Catalyst(r) OS and Cisco IOS(r) Software command input, output, and logging Use instructor-developed problem-isolation methods to resolve Trouble Tickets
"Sniff" the wire to spot network issues
Analyze local and remote access problems in Ethernet networks, including issues with cabling, speed and duplex, utilization and collisions, bandwidth, CSMA/CD, one-way link, auto negotiation, addressing, encapsulation, and more
Apply a layered troubleshooting methodology to real-life routing and switching environments
Designed for aspiring CCNP and CCIE(r) professionals, this indispensable lab guide builds on Cisco(r) Internetwork Troubleshooting (CIT) topics that prepare you for the CCNP
Troubleshooting exam. Full of practical exercises that get you ready for challenges on the job, CCNP Practical Studies: Troubleshooting gives you an edge over the competition through real- world application of LAN and WAN topics.
CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including r2#clear counters
Clear "show interface" counters on all interfaces [confirm]
r2#
01:22:56: %CLEAR-5-COUNTERS: Clear counter on all interfaces by console r2#show interfaces ethernet 0
Ethernet0 is up, line protocol is up
Hardware is Lance, address is 0000.0c38.a05d (bia 0000.0c38.a05d) Description: r2 e0 to HostC Win98Dell
Internet address is 192.168.3.1/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255 Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:43, output 00:00:04, output hang never Last clearing of "show interface" counters 00:00:19 Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected
2 packets output, 120 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out r2>