Shooting Trouble with CatOS and IOS

Ethernet II DIX Ethernet) Frame Format

Chapter 6. Shooting Trouble with CatOS and IOS

Cisco started its internetworking revolution with routers, but soon found out with the help of those they acquired that switches are quite beneficial, too. A solid understanding of switches and routers is crucial for supporting networks as well as obtaining your CCNP and other industry certifications. This chapter assumes knowledge of the previous chapters, but in particular Chapter 5, "Shooting Trouble with Ethernet," and Chapter 3, "Shooting Trouble with IP."

In this chapter you eliminate any hubs and connect your hosts to Cisco switches to build the scenario. Then you review Ethernet switching concepts, symptoms, problems, and action plans.

Throughout the chapter there are several walk-through scenarios and practical Trouble Tickets for you to explore. For those of you who do not have equipment handy, the rest of this book contains many relevant figures, examples, and explanations so that you too can follow along to gain practical experience.

This chapter covers the following topics:

Scenario: Shooting Trouble with CatOS and IOS Segmentation Review

Spanning Tree Protocol (STP)

The Cisco Command-Line Interface (CLI) Cat5000/Cat6000 Architecture

Shooting Trouble with Switches Trouble Tickets

Trouble Tickets Solutions

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

Scenario: Shooting Trouble with CatOS and IOS

This chapter requires changes to your physical topology. You configure the Cisco routers and switches as shown Figure 6-1. The rest of the chapter deploys this scenario, so be sure to save your configurations before, during, and after. For example, I saved my Chapter 5 configurations to a file called Chapter 5 Ending Configs.

Figure 6-1. Shooting Trouble with CatOS and IOS

Ideally, you should have at least one CatOS-based switch and one IOS-based switch. The CatOS uses the set, show, clear syntax, whereas the IOS is more like using the command-line interface (CLI) of a router. I picked three different switches for the scenario so that you get a feel for using HTTP and menus on a 1900, IOS on a 3512XL, and CatOS on a 2900. The 2900 CatOS box has many similarities to the 4000/5000/6000 family of Cisco switches. Although the 2900 in my lab has been discontinued for several years, it's basically a fixed configuration 5002, limited to a Supervisor I. By all means, if you have access to newer devices (such as 6509s), use them instead. My point of using the older ones is to illustrate the fact that you don't need to spend a lot of money on new devices to learn how to troubleshoot.

NOTE

What this chapter is not is a device manual for all of Cisco's switches. If you want that, go to Cisco.com, search for "cisco product quick reference guide" to view it online or order your own subscription. The quick reference guide includes product overviews, photos, technical specifications, and more.

• 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

"Sniff" the wire to spot network issues

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

CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including

I will briefly review such topics as segmentation, switching modes, speed and duplex settings, the switched port analyzer (SPAN) for port monitoring, and the Spanning Tree Protocol (STP) to assist you with supporting

switched Ethernet environments. As in the other practical study support topics, it is essential for you to

continue to identify targets and document the results using such commands as ping, trace, set, show, clear, and other troubleshooting utilities.

The scenario goal is to analyze real-world Catalyst switch issues including physical, data-link, and configuration errors. Document your steps and any problems along the way. For this chapter keep everything on subnet 192.168.5.96/28 and assume no VLANs other than the default. Ensure that you can telnet to each switch to configure it. Optionally attach the switches to the terminal server for convenience. Configure the switches starting with the 1900 first, then the 3512XL IOS-based switch, and finally the 2900 CatOS switch as shown in Figure 6-1. On the router, advertise loopback 10 (192.168.6.100/28) in RIP to simulate an external network.

Save your work, and don't forget to test things out. All hosts should be able to communicate with the servers you choose to set up on your server farm off of the 2900 as well as to the outside world.

There is not always one right or wrong way to accomplish the tasks presented. The ability to obtain the end result using good practices is extremely important in any real-world network. Where specific parameters are not given, feel free to make the necessary choices to work through the scenario. Troubleshooting and device configurations are included so that you can compare your work and perhaps see a different approach to obtaining the end result. Use the previous IP (Table 3-1) and Ethernet (Table 5-1) quick checklists, your step- by-step troubleshooting methodology and intuition, and the switch quick checklist in Table 6-1 to assist in testing.

The switch troubleshooting checklist in Table 6-1 assumes that you are familiar with the Ethernet and IP quick troubleshooting checklists from the previous chapters, so those commands are not repeated here. Instead, Table 6-1 displays how to quickly spot issues with modules and ports because they are the main targets for switch troubleshooting. A more complete table of CatOS and IOS commands is provided in the section "The Cisco Command-Line Interface (CLI)."

Table 6-1. Switch Quick Troubleshooting Checklist

CatOS Syntax IOS Syntax

show cdp neighbors >show cdp neighbors

show module >show module

show version >show version

show config/write terminal #show config/show startup-config

show arp >show arp

show cam dynamic #show mac-address-table

show port #show interface status

set trace #debug

This chapter scenario's switch, router, and host configurations are displayed starting in Example 6-1. The 1900 switch is not running the Enterprise Edition of the software, so the CLI is not available. Instead of upgrading the software, reset the switch to its factory defaults using the menus as in Example 6-1.

• 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

"Sniff" the wire to spot network issues

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

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 6-1. Resetting the 1900 to the Factory Defaults Using the Menu Interface

Catalyst 1900 Management Console

Standard Edition Software

Ethernet Address: 00-90-92-2A-76-80 PCA Number: 73-2239-05

PCA Serial Number: FAA02291854 Model Number: WS-C1924-A System Serial Number: FAA0227W0U1

--- 1 user(s) now active on Management Console.

User Interface Menu [M] Menus

[I] IP Configuration Enter Selection: M

Catalyst 1900 - System Configuration

System Revision: 1 Address Capacity: 1024

System UpTime: 0day(s) 00hour(s) 00minute(s) 45second(s)

--- Settings --- [N] Name of system sw1900

[C] Contact name donna l harrington [L] Location broad creek

[S] Switching mode Store-and-Forward [U] Use of store-and-forward for multicast Disabled

[A] Action upon address violation Disable

• 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

"Sniff" the wire to spot network issues

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

CCNP Practical Studies: Troubleshooting provides you with practical information on all the important concepts central to the troubleshooting portion of the CCNP certification, including [G] Generate alert on address violation Disabled

[I] Address aging time 300 second(s) [P] Network port None

[H] Half duplex back pressure (10-mbps ports) Disabled [E] Enhanced congestion control (10-mbps ports) Adaptive

--- Actions --- [R] Reset system [F] Reset to factory defaults --- Related Menus --- [B] Broadcast storm control [X] Exit to Main Menu

Enter Selection: F

This command resets the switch with factory defaults. All system parameters will revert to their default factory settings. All static and dynamic addresses will be removed.

Reset system with factory defaults, [Y]es or [N]o? Yes

Next configure the IP parameters and make sure HTTP is operational on port 80 as in Examples 6-2 and 6-3.

Example 6-2. Setting the IP Parameters on the 1900 (HTTP Port 80)

Catalyst 1900 - Main Menu [C] Console Settings [S] System

[N] Network Management [P] Port Configuration ...

[H] Help

[X] Exit Management Console Enter Selection: N

• 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

"Sniff" the wire to spot network issues

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

[I] IP Configuration [S] SNMP Management

[B] Bridge - Spanning Tree [C] Cisco Discovery Protocol

[G] Cisco Group Management Protocol [H] HTTP Server Configuration

[X] Exit to Main Menu Enter Selection: H

Catalyst 1900 - HTTP Server Configuration

--- Settings --- [H] HTTP Enabled

[P] HTTP Port 80 [X] Exit to previous menu

Enter Selection: X

The shaded output indicates that HTTP port 80 is the default on the 1900. HTTP and menus are generally available on Cisco switches, but not always configured as the default for security reasons. For example, the global command ip http server enables this on my IOS switch, although most people want to know how to disable such features. Type no ip http server to disable it afterward if you want to experiment with the web- based Visual Switch Manager on the 3512XL.

Next, set the IP address on the 1900 as in Example 6-3 so that you can manage the device remotely.

Example 6-3. Setting the IP Parameters on the 1900 (Address)

Catalyst 1900 - Network Management [I] IP Configuration

[S] SNMP Management

• 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

"Sniff" the wire to spot network issues

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

[C] Cisco Discovery Protocol

[G] Cisco Group Management Protocol [H] HTTP Server Configuration

[X] Exit to Main Menu Enter Selection: I

Catalyst 1900 - IP Configuration Ethernet Address: 00-90-92-2A-76-80

--- Settings --- [I] IP address 0.0.0.0

[S] Subnet mask 0.0.0.0 [G] Default gateway 0.0.0.0 [M] IP address of DNS server 1 0.0.0.0 [N] IP address of DNS server 2 0.0.0.0 [D] Domain name

[R] Use Routing Information Protocol Enabled

--- Actions --- [P] Ping

[X] Exit to previous menu Enter Selection: I

This command assigns an administrative IP address to this switch.

The new address will take effect immediately.

If no IP address is assigned (or if the IP address is removed by setting it to 0.0.0.0), and the switch is connected to a DHCP server, the DHCP server may automatically assign an address to the switch.

Enter administrative IP address in dotted quad format (nnn.nnn.nnn.nnn):

Current setting ===> 0. 0. 0. 0

What's in Your Tool Bag?

Shooting Trouble with Novell IPX