Ethernet II DIX Ethernet) Frame Format
Chapter 7. Shooting Trouble with VLANs
This chapter continues the practical switching focus and includes a number of objectives falling under the CCNP troubleshooting guidelines. Understanding and supporting Ethernet switches, routers, and virtual LANs (VLANs) applies to all of Cisco's current certifications. A solid
understanding of VLANs and the role of routers and switches in the internetwork is essential in your practical studies. This chapter assumes knowledge of the previous chapters, but in
particular of Chapter 3, "Shooting Trouble with IP," Chapter 5, "Shooting Trouble with Ethernet,"
and Chapter 6, "Shooting Trouble with CatOS and IOS."
You build the chapter scenario to assist you in supporting routing and switching using VLANs.
The chapter reviews VLAN concepts, symptoms, problems, and action plans while you configure your VLANs. As you are used to by now, 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, I include many relevant figures and examples so that you too can shoot trouble with VLANs.
This chapter covers the following topics:
Scenario: Shooting Trouble with VLANs on Routers and Switches Why VLANs?
Trunking
Managing VLANs Inter-VLAN Routing
Route Switch Technologies Shooting Trouble with VLANs 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
• 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 VLANs on Routers and Switches
The chapter scenario uses some of the same routers and switches you have configured for the other scenarios. You modify your lab according to Figure 7-1 and start with everything in VLAN1.
Figure 7-1. Chapter 7 Scenario Physical Layout
Document your steps and any problems along the way. Remember, however, that there is not always one right way to accomplish the tasks presented. The ability to obtain the end result using good practices is extremely important in any real-world network. My troubleshooting and device configurations are presented starting in Example 7-1 so that you can compare your work and perhaps see a different approach to obtaining the end result. Use the previous
troubleshooting checklists, your step-by-step troubleshooting methodology, and the VLAN checklist in Table 7-1 to assist in testing.
Table 7-1. VLAN Quick Troubleshooting Checklist
• 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
CatOS IOS
set vtp domain donna #vlan database
(vlan)#vtp domain donna set vtp mode transparent (vlan)#vtp transparent
vlan 2 name eng type ethernet (vlan)#vlan 2 name eng media ethernet show vlan
show spantree vlan#
(vlan)#show
#show spanning-tree vlan#
clear vlan 2 (vlan)#no vlan 2 name eng media ethernet (vlan)#exit
show vtp domain #show vtp status
set trunk 1/1-2 on (config)#interface fa0/12
(config-if)#switchport mode trunk
show trunk #show interface fa0/12 switchport
show spantree ?
show port spantree 2/4
#show spanning-tree ?
#show spannting-tree interface fa0/1 See also
www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12111ea1/scg/swvlan.htm#xtocid7.
As I discuss real-world VLAN-to-VLAN communication—including issues such as addressing the broadcast domains, default gateways, VLAN Trunking Protocol (VTP) mode tuning, trunking issues, routing issues, vanishing VLANs, and so on—continue to identify targets and document the results using ping, trace, set, show, clear, Cisco Discovery Protocol (CDP), debug, protocol analyzers, and other troubleshooting tools.
First you should physically disconnect all serial and Ethernet cables and wire your lab according to Figure 7-1. My terminal server is a 2511 (not pictured in the diagram), r1 is a 2514, r2 is a 2501, r3 is a 3640, the IOS-based switch is a 3512XL, and the CatOS-based switch is a 2900.
The 1900 used in the preceding chapter is not being used here. I am assuming you have a Fast Ethernet connection from r3 to the 3512XL switch as well as between the switches. My
connections between r1/r2 and their respective switches are only 10 Mbps, but 10 or 100 is fine.
Assuming you have the correct number and type of interfaces, other equipment is suitable, too.
Configure the terminal server (optional) and clear the configurations. The write erase or erase startup-config command followed by the reload command works fine for the routers and the IOS-based switch. Use clear config all for the CatOS box.
Inspect the LEDs for all devices and prepare for console or terminal server connectivity to each device. Globally configure such items as hostnames and passwords. Configure what is
appropriate for the router interfaces, including descriptions, speed and duplex settings,
bandwidth, and clock rate. Remember to issue a no shut on the interfaces and turn on logging synchronous for the console. Use the default encapsulations but do not configure the IP
parameters as of yet. Example 7-1 displays the r1 configuration.
Example 7-1. r1 Configuration
• 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 Router>enable
Router#configure terminal Router(config)#hostname r1 r1(config)#enable secret donna r1(config)#line vty 0 4
r1(config-line)#login
r1(config-line)#password donna
r1(config-line)#interface ethernet 0
r1(config-if)#description r1e0 to sw2900 2/1 r1(config-if)#speed 10
r1(config-if)#duplex half r1(config-if)#no shut
r1(config-if)#interface serial 1
r1(config-if)#description r1s1 to r2s1 r1(config-if)#bandwidth 64
r1(config-if)#clock rate 64000 r1(config-if)#no shut
r1(config-if)#exit
r1(config)#line console 0
r1(config-line)#logging synchronous r1(config-line)#end
r1#copy running-config startup-config
Speed and duplex settings may or may not be available depending upon your hardware and software.
Next configure r2 as in Example 7-2.
• 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 7-2. r2 Configuration
Router(config)#hostname r2 r2(config)#enable secret donna r2(config)#line vty 0 4
r2(config-line)#login
r2(config-line)#password donna
r2(config-line)#interface ethernet 0
r2(config-if)#description r2e0 to sw3512xl fa0/12 r2(config-if)#speed 10
r2(config-if)#duplex half r2(config-if)#no shut
r2(config-if)#interface serial 0
r2(config-if)#description r2s0 to r3s0/0 r2(config-if)#bandwidth 64
r2(config-if)#no shut
r2(config-if)#interface serial 1
r2(config-if)#description r2s1 to r1s1 r2(config-if)#bandwidth 64
r2(config-if)#no shut r2(config-if)#exit
r2(config)#line console 0
r2(config-line)#logging synchronous r2(config-line)#end
r2#show ip interface brief
Interface IP-Address OK? Method Status Protocol Ethernet0 unassigned YES unset up up
Serial0 unassigned YES unset down down
• 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 Serial1 unassigned YES unset up up r2# copy running-config startup-config
Now that Layer 1 and Layer 2 are up for r1 and r2, move along to configure r3 as in Example 7- 3.
Example 7-3. r3 Configuration
Router(config)#hostname r3 r3(config)#enable secret donna r3(config)#line vty 0 4
r3(config-line)#login
r3(config-line)#password donna
r3(config-line)#interface fastethernet 2/0
r3(config-if)#description r3 fa2/0 to sw3512xl fa0/10 r3(config-if)#speed 100
r3(config-if)#full-duplex r3(config-if)#no shut
r3(config)#interface serial 0/0
r3(config-if)#description r3s0/0 to r2s0 r3(config-if)#bandwidth 64
r3(config-if)#clock rate 64000 r3(config-if)#no shut
r3(config-if)#exit
r3(config)#line console 0
r3(config-line)#logging synchronous r3(config-line)#end
r3#show ip interface brief
Interface IP-Address OK? Method Status Protocol
• 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 Serial0/0 unassigned YES unset up up ...
FastEthernet2/0 unassigned YES unset up up r3#copy running-config startup-config
Now that the basic router configurations are in place, configure the switches as in Examples 7-4, 7-5, and 7-6 (including the hostnames, passwords, and most appropriate duplex, speed, and portfast settings). Verify CDP communications from both switches as a quick physical test as in Example 7-7.
Example 7-4. sw3512XL IOS Switch Configuration
Switch(config)#hostname sw3512xl sw3512xl(config)#enable secret donna sw3512xl(config)#line vty 0 4
sw3512xl(config-line)#login
sw3512xl(config-line)#password donnna
sw3512xl(config-line)#!!!better to fix this now than later sw3512xl(config-line)#password donna
sw3512xl(config-line)#interface fastethernet 0/1
sw3512xl(config-if)#description sw3512xl fa0/1 to hosta sw3512xl(config-if)#speed 100
sw3512xl(config-if)#duplex full
sw3512xl(config-if)#spanning-tree portfast sw3512xl(config-if)#no shut
sw3512xl(config-if)#interface fastethernet 0/2
sw3512xl(config-if)#description sw3512xl fa0/2 to hostb sw3512xl(config-if)#speed 10
sw3512xl(config-if)#duplex half