Cisco Nexus 1000V User manual

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Americas Headquarters
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
USA
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Tel: [phone]
800 553-NETS (6387)
Fax: [phone]
Cisco Nexus 1000V Troubleshooting
Guide, Release 4.2(1)SV2(2.1)
April 13, 2015
Text Part Number: OL-28795-01

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THE SPECIFICATIONS AND INFORMATION REGARDING THE PRODUCTS IN THIS MANUAL ARE SUBJECT TO CHANGE WITHOUT NOTICE. ALL
STATEMENTS, INFORMATION, AND RECOMMENDATIONS IN THIS MANUAL ARE BELIEVED TO BE ACCURATE BUT ARE PRESENTED WITHOUT
WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. USERS MUST TAKE FULL RESPONSIBILITY FOR THEIR APPLICATION OF ANY PRODUCTS.
THE SOFTWARE LICENSE AND LIMITED WARRANTY FOR THE ACCOMPANYING PRODUCT ARE SET FORTH IN THE INFORMATION PACKET THAT
SHIPPED WITH THE PRODUCT AND ARE INCORPORATED HEREIN BY THIS REFERENCE. IF YOU ARE UNABLE TO LOCATE THE SOFTWARE LICENSE
OR LIMITED WARRANTY, CONTACT YOUR CISCO REPRESENTATIVE FOR A COPY.
The Cisco implementation of TCP header compression is an adaptation of a program developed by the University of California, Berkeley (UCB) as part of UCB’s public
domain version of the UNIX operating system. All rights reserved. Copyright © 1981, Regents of the University of California.
NOTWITHSTANDING ANY OTHER WARRANTY HEREIN, ALL DOCUMENT FILES AND SOFTWARE OF THESE SUPPLIERS ARE PROVIDED “AS IS” WITH
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IN NO EVENT SHALL CISCO OR ITS SUPPLIERS BE LIABLE FOR ANY INDIRECT, SPECIAL, CONSEQUENTIAL, OR INCIDENTAL DAMAGES, INCLUDING,
WITHOUT LIMITATION, LOST PROFITS OR LOSS OR DAMAGE TO DATA ARISING OUT OF THE USE OR INABILITY TO USE THIS MANUAL, EVEN IF CISCO
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Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this
URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership
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Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the
document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
Cisco Nexus 1000V Troubleshooting Guide, Release 4.2(1)SV2(2.1)
© 2013 Cisco Systems, Inc. All rights reserved.

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CONTENTS
New and Changed Information xiii
Preface xv
Audience xv
Document Conventions xv
Related Documentation xvi
Obtaining Documentation and Submitting a Service Request xviii
xviii
Overview of Troubleshooting 1-1
Overview of the Troubleshooting Process 1-1
Overview of Best Practices 1-1
Troubleshooting Basics 1-2
Troubleshooting Guidelines 1-2
Gathering Information 1-2
Verifying Ports 1-3
Verifying Layer 2 Connectivity 1-3
Verifying Layer 3 Connectivity 1-3
Overview of Symptoms 1-4
System Messages 1-4
System Message Text 1-4
Syslog Server Implementation 1-5
Troubleshooting with Logs 1-6
Viewing Logs 1-6
Cisco Support Communities 1-7
Contacting Cisco or VMware Customer Support 1-7
Tools Used in Troubleshooting 2-1
Commands 2-1
Ping 2-1
Traceroute 2-2
Monitoring Processes and CPUs 2-2
Identifying the Processes Running and their States 2-2
Displaying CPU Utilization 2-3

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Displaying CPU and Memory Information 2-4
RADIUS 2-4
Syslog 2-5
Logging Levels 2-5
Enabling Logging for Telnet or SSH 2-6
Installation 3-1
Isolating Installation Problems 3-1
Verifying Your VMware License Version 3-1
Host is Not Visible from Distributed Virtual Switch 3-2
Refreshing the vCenter Server Connection 3-3
Improving Performance 3-4
Verifying the Domain Configuration 3-4
Verifying the Port Group Assignments for a VSM VM Virtual Interface 3-4
Verifying VSM and vCenter Server Connectivity 3-5
Troubleshooting Connections to a vCenter Server 3-5
Recovering the Network Administrator Password 3-6
Managing Extension Keys 3-6
Known Extension Problems and Resolutions 3-7
Resolving a Plug-In Conflict 3-7
Finding the Extension Key on the Cisco Nexus 1000V 3-7
Finding the Extension Key Tied to a Specific DVS 3-8
Verifying Extension Keys 3-9
Recreating the Cisco Nexus 1000V Installation 3-10
Removing the Hosts from the Cisco Nexus 1000V DVS 3-11
Removing the Cisco Nexus 1000V From the vCenter Server 3-11
Unregister the Extension Key in the vCenter Server 3-12
Problems with the Nexus 1000V Installation Management Center 3-13
Licenses 4-1
Information About Licenses 4-1
Contents of the License File 4-2
Prerequisites to License Troubleshooting 4-2
Problems with Licenses 4-3
License Troubleshooting Commands 4-4
Upgrade 5-1
Information about Upgrades 5-1
Problems with the In Service Software Upgrade 5-1

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Problems with the VEM Upgrade 5-5
Problems with the GUI Upgrade 5-6
Recovering a Secondary VSM with Active Primary 5-8
Stopping a VSM Upgrade 5-9
Changing Boot Variables 5-10
Powering On the VSM 5-11
Changing the HA Role 5-12
Recovering a Primary VSM with Active Secondary 5-13
Disconnecting the Port Groups 5-13
Powering Off the VSM 5-15
Connecting the Port Groups 5-15
Problems with VSM-VEM Layer 2 to 3 Conversion Tool 5-17
Upgrade Troubleshooting Commands 5-17
High Availability 6-1
Information About High Availability 6-1
System-Level High Availability 6-2
Network-Level High Availability 6-2
Problems with High Availability 6-2
High Availability Troubleshooting Commands 6-5
VSM and VEM Modules 7-1
Information About Modules 7-1
Troubleshooting a Module Not Coming Up on the VSM 7-1
Guidelines for Troubleshooting Modules 7-2
Flow Chart for Troubleshooting Modules 7-3
Problems with the VSM 7-4
Verifying the VSM Is Connected to the vCenter Server 7-6
Verifying the VSM Is Configured Correctly 7-7
Verifying the Domain Configuration 7-7
Verifying the System Port Profile Configuration 7-8
Verifying the Control and Packet VLAN Configuration 7-8
Checking the vCenter Server Configuration 7-10
Checking Network Connectivity Between the VSM and the VEM 7-10
Recovering Management and Control Connectivity of a Host when a VSM is Running on a VEM 7-12
Using the VEM Connect Script 7-12
Checking the VEM Configuration 7-14
Collecting Logs 7-17
VSM and VEM Troubleshooting Commands 7-18

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Ports 8-1
Information About Ports 8-1
Information About Interface Characteristics 8-1
Information About Interface Counters 8-2
Information About Link Flapping 8-2
Information About Port Security 8-2
Port Diagnostic Checklist 8-3
Problems with Ports 8-3
Cannot Enable an Interface 8-4
Port Link Failure or Port Not Connected 8-4
Link Flapping 8-5
Port ErrDisabled 8-5
VM Cannot Ping a Secured Port 8-6
Port Security Violations 8-7
Port Troubleshooting Commands 8-8
Port Profiles 9-1
Information About Port Profiles 9-1
Problems with Port Profiles 9-2
Recovering a Quarantined Offline Interface 9-5
Port Profile Logs 9-6
Port Profile Troubleshooting Commands 9-6
Port Channels and Trunking 10-1
Overview 10-1
Port Channel Overview 10-1
Port Channel Restriction 10-2
Trunking Overview 10-2
Initial Troubleshooting Checklist 10-2
Troubleshooting Asymmetric Port Channels 10-3
Cannot Create Port Channel 10-4
Newly Added Interface Does Not Come Online In a Port Channel 10-4
Forcing Port Channel Characteristics onto an Interface 10-4
Verifying a Port Channel Configuration 10-5
VLAN Traffic Does Not Traverse Trunk 10-5
Layer 2 Switching 11-1
Information About Layer 2 Ethernet Switching 11-1
Port Model 11-1

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Viewing Ports from the VEM 11-2
Viewing Ports from the VSM 11-3
Port Types 11-4
Layer 2 Switching Problems 11-4
Verifying a Connection Between VEM Ports 11-4
Verifying a Connection Between VEMs 11-5
Isolating Traffic Interruptions 11-6
Verifying Layer 2 Switching 11-7
Troubleshooting Microsoft NLB Unicast Mode 11-12
Limitations and Restrictions 11-12
Disabling Automatic Static MAC Learning on vEthernet 11-12
Checking Status on a VSM 11-12
Checking Status on a VEM 11-13
Configuring MS NLB for Multiple VM NICs in the Same Subnet 11-14
Enabling UUFB 11-14
Disabling UUFB for VMs that use Dynamic MAC Addresses 11-14
VLANs 12-1
Information About VLANs 12-1
Initial Troubleshooting Checklist 12-2
Cannot Create a VLAN 12-3
Private VLANs 13-1
Information About Private VLANs 13-1
Private VLAN Domain 13-1
Spanning Multiple Switches 13-1
Private VLAN Ports 13-2
Troubleshooting Guidelines 13-2
Private VLAN Troubleshooting Commands 13-2
NetFlow 14-1
Information About NetFlow 14-1
NetFlow Troubleshooting Commands 14-2
Common NetFlow Problems 14-3
Debugging a Policy Verification Error 14-3
Debugging Statistics Export 14-3
ACLs 15-1
About Access Control Lists (ACLs) 15-1
ACL Configuration Limits 15-1

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ACL Restrictions 15-2
Troubleshooting ACLs 15-2
Displaying ACL Policies on the VEM 15-2
Debugging Policy Verification Issues 15-3
Troubleshooting ACL Logging 15-3
Using the CLI to Troubleshoot ACL Logging on a VEM 15-4
Viewing Current Flows 15-4
Viewing Active Flows 15-4
Flushing All ACL Flows 15-4
Showing Flow Debug Statistics 15-5
ACL Logging Troubleshooting Scenarios 15-5
Troubleshooting a Syslog Server Configuration 15-5
Troubleshooting an ACL Rule That Does Not Have a Log Keyword 15-6
Troubleshooting a Maximum Flow Limit Value That is Too Low 15-6
Troubleshooting a Mismatched Configuration between a VSM and a VEM 15-7
Quality of Service 16-1
Information About Quality of Service 16-1
QoS Configuration Limits 16-1
QoS Troubleshooting Commands 16-2
Troubleshooting the VEM 16-2
Debugging Policing Verification Errors 16-3
SPAN 17-1
Information About SPAN 17-1
SPAN Session Guidelines 17-1
Problems with SPAN 17-2
SPAN Troubleshooting Commands 17-3
Multicast IGMP 18-1
Information About Multicast 18-1
Multicast IGMP Snooping 18-1
Problems with Multicast IGMP Snooping 18-2
Troubleshooting Guidelines 18-2
Troubleshooting Commands 18-2
Symptoms, Causes, and Solutions 18-4
DHCP, DAI, and IPSG 19-1
Information About DHCP Snooping 19-1
Information About Dynamic ARP Inspection 19-2

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Information About IP Source Guard 19-2
Guidelines and Limitations for Troubleshooting 19-2
Problems with DHCP Snooping 19-3
Troubleshooting Dropped ARP Responses 19-4
Problems with IP Source Guard 19-5
Collecting and Evaluating Logs 19-5
VSM Logging 19-5
Host Logging 19-6
DHCP, DAI, and IPSG Troubleshooting Commands 19-6
Virtual Service Domain 20-1
Information about Virtual Service Domain 20-1
Problems with Virtual Service Domain 20-1
Collecting and Evaluating Logs 20-2
Virtual Service Domain Troubleshooting Commands 20-3
System 21-1
Information About the System 21-1
General Restrictions for vCenter Server 21-2
Extension Key 21-2
Recovering a DVS 21-2
Recovering a DVS With a Saved Copy of the VSM 21-3
Recovering a DVS Without a Saved Copy of the VSM 21-4
Problems Related to VSM and vCenter Server Connectivity 21-5
Connection Failure After ESX Reboot 21-6
Setting the System MTU 21-7
Recovering Lost Connectivity Due to MTU Mismatch 21-8
VSM Creation 21-9
Port Profiles 21-9
Problems with Port Profiles 21-10
Problems with Hosts 21-10
Problems with VM Traffic 21-10
VEM Troubleshooting Commands 21-11
VEM Log Commands 21-12
Error Messages 21-12
Network Segmentation Manager 22-1
Information About Network Segmentation Manager 22-1

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Problems with Network Segmentation Manager 22-2
Network Segmentation Manager Troubleshooting Commands 22-7
VXLANs 23-1
Information About VXLANs 23-1
Overview 23-1
VXLAN Tunnel EndPoint 23-2
VXLAN Gateway 23-2
VXLAN Trunks 23-2
Multi-MAC Capability 23-3
Fragmentation 23-3
Scalability 23-3
Maximum Number of VXLANs 23-3
Supported Features 23-3
Jumbo Frames 23-3
Disabling the VXLAN Feature Globally 23-4
VXLAN Troubleshooting Commands 23-4
VSM Commands 23-4
VXLAN Gateway Commands 23-5
VEM Commands 23-7
VEM Packet Path Debugging 23-9
VEM Multicast Debugging 23-10
VXLAN Datapath Debugging 23-11
Vemlog Debugging 23-11
Vempkt 23-12
Statistics 23-12
Show Commands 23-13
Cisco TrustSec 24-1
Information About Cisco TrustSec 24-1
Guidelines and Limitations for Troubleshooting Cisco TrustSec 24-1
Cisco TrustSec Troubleshooting Commands 24-2
Debugging Commands 24-2
Host Logging Commands 24-3
Example 24-3
Show Commands 24-4
Problems with Cisco TrustSec 24-4
vCenter Plug-in 25-1
vCenter Plug-in Overview 25-1

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Requirements for VMware vSphere Web Client 25-1
Generating a Log Bundle 25-2
Ethanalyzer 26-1
Using Ethanalyzer 26-1
Before Contacting Technical Support 27-1
Cisco Support Communities 27-1
Gathering Information for Technical Support 27-1
Obtaining a File of Core Memory Information 27-2
Copying Files 27-3
I NDEX

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New and Changed Information
This section describes the information in this document that is either new or has changed with each
release.
To find additional information about new features or command changes, see the following:
•Release Notes.
•Command Reference.
Feature Description
Changed in
release Where Documented
VXLAN Gateway Added section for troubleshooting
commands for VXLAN Gateway.
4.2(1)SV2(2.1) “VXLANs”
Upgrade Added section for problems with
VSM-VEM Layer 2 to 3 Conversion Tool.
4.2(1)SV2(1.1) Upgrade
Ethanalyzer Added Ethanalyzer as a Nexus 1000V
protocol analyzer tool content.
4.2(1)SV2(1.1) Ethanalyzer
DHCP Enhancements Added the troubleshooting commands for
DHCP.
4.2(1)SV2(1.1) DHCP, DAI, and IPSG
Troubleshooting Commands
High Availability Updated the high availability section.
Added command output for the new
command show system internal
active-active remote accounting logs and
updated the output for the show system
redundancy status command.
4.2(1)SV2(1.1) High Availability
Licensing Added the svs license transfer src-vem
<vem no> license_pool command to
troubleshoot the issues with checking out
the licenses or returning them to the
license pool.
4.2(1)SV2(1.1) License Troubleshooting
Commands
Nexus 1000V VC Plugin
Installation
Added new section to troubleshoot the
Nexus 1000V VC Plugin Installation.
4.2(1)SV2(1.1) vCenter Plug-in
Nexus 1000V Installation
Management Center
Added new section to troubleshoot the
Nexus 1000V Installation Management
Center.
4.2(1)SV1(5.1) “Problems with the Nexus 1000V
Installation Management Center”

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New and Changed Information
Recovering Management
and Control Connectivity
of a Host
Added new section to recover management
and control connectivity of a host when a
VSM is running on a VEM
4.2(1)SV1(5.1) “Recovering Management and
Control Connectivity of a Host
when a VSM is Running on a
VEM”
ACL Logging Added new section to troubleshoot ACL
Logging.
4.2(1)SV1(5.1) “Troubleshooting ACL Logging”
NSM Added new chapter to troubleshoot the
Network Segmentation Manager (NSM).
4.2(1)SV1(5.1) “Network Segmentation Manager”
VXLAN Added new chapter to troubleshoot the
Virtual Extensible Local Area Network
(VXLAN).
4.2(1)SV1(5.1) “VXLANs”
Microsoft NLBUnicast
Mode
Added new section for troubleshooting
Microsoft Network Load Balancing
(NLB) Unicast mode
4.2(1)SV1(5.1) “Layer 2 Switching”
In service software
upgrade (ISSU)
Added new section for troubleshooting
ISSU.
4.2(1)SV1(4a) “Upgrade”
VEM software upgrade Added new section for troubleshooting
VEM software upgrade.
4.2(1)SV1(4a) “Upgrade”
DHCP, DAI, IPSG Added new section for troubleshooting
DHCP, Dynamic ARP Inspection, and IP
Source Guard.
4.2(1)SV1(4) “DHCP, DAI, and IPSG”
Virtual Service Domain Added new section for troubleshooting
Virtual Service Domain.
4.2(1)SV1(4) “Virtual Service Domain”
Port profiles Added section for port profiles, new
information about quarantined port
profiles.
4.2(1)SV1(4) “Port Profiles”
Upgrade Added new section for troubleshooting
upgrade problems.
4.2(1)SV1(4) “Upgrade”
VEM health check The VEM health check shows the cause of
a connectivity problem and recommends
next steps in troubleshooting.
4.0(4)SV1(3) “Checking Network Connectivity
Between the VSM and the VEM”
VSM connection failure
after ESX reboot
The section describes how to prevent loss
of connectivity related to an MTU
mismatch following a reboot of the ESX.
4.0(4)SV1(3) “Connection Failure After ESX
Reboot”
Feature Description
Changed in
release Where Documented

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Preface
The Troubleshooting document provides information about how to recognize a problem, determine its
cause, and find possible solutions.
This preface describes the following aspects of this document:
•Audience, page xv
•Document Conventions, page xv
•Related Documentation, page xvi
•Obtaining Documentation and Submitting a Service Request, page xviii
Audience
This publication is for experienced network administrators who configure and maintain a Cisco Nexus
1000V.
Document Conventions
Command descriptions use these conventions:
Screen examples use these conventions:
Convention Description
boldface font Commands and keywords are in boldface.
italic font Arguments for which you supply values are in italics.
[ ] Elements in square brackets are optional.
[ x | y | z ] Optional alternative keywords are grouped in brackets and separated by vertical
bars.
string A nonquoted set of characters. Do not use quotation marks around the string or
the string will include the quotation marks.
screen font Terminal sessions and information that the switch displays are in screen font.
boldface screen
font
Information that you must enter is in boldface screen font.

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Preface
This document uses the following conventions:
Note Means reader take note. Notes contain helpful suggestions or references to material not covered in the
manual.
Caution Means reader be careful. In this situation, you might do something that could result in equipment
damage or loss of data.
Related Documentation
This section lists the documents used with the Cisco Nexus 1000 and available on Cisco.com at the
following URL:
http://www.cisco.com/en/US/products/ps9902/tsd_products_support_series_home.html
General Information
Cisco Nexus 1000V Documentation Roadmap
Cisco Nexus 1000V Release Notes
Cisco Nexus 1000V Compatibility Information
Install and Upgrade
Cisco Nexus 1000V Installation and Upgrade Guide
Configuration Guides
Cisco Nexus 1000V High Availability and Redundancy Configuration Guide
Cisco Nexus 1000V Interface Configuration Guide
Cisco Nexus 1000V Layer 2 Switching Configuration Guide
Cisco Nexus 1000V License Configuration Guide
Cisco Nexus 1000V Network Segmentation Manager Configuration Guide
Cisco Nexus 1000V Port Profile Configuration Guide
Cisco Nexus 1000V Quality of Service Configuration Guide
Cisco Nexus 1000V REST API Plug-in Configuration Guide
Cisco Nexus 1000V Security Configuration Guide
italic screen font Arguments for which you supply values are in italic screen font.
< > Nonprinting characters, such as passwords, are in angle brackets.
[ ] Default responses to system prompts are in square brackets.
!, # An exclamation point (!) or a pound sign (#) at the beginning of a line of code
indicates a comment line.

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Preface
Cisco Nexus 1000V System Management Configuration Guide
Cisco Nexus 1000V vCenter Plugin Configuration Guide
Cisco Nexus 1000V VXLAN Configuration Guide
Cisco Nexus 1000V vCenter Plugin Configuration Guide
Programming Guide
Cisco Nexus 1000V XML API User Guide
Reference Guides
Cisco Nexus 1000V Command Reference
Cisco Nexus 1000V MIB Quick Reference
Cisco Nexus 1000V Resource Availability Reference
Troubleshooting, Password Recovery, System Messages Guides
Cisco Nexus 1000V Troubleshooting Guide
Cisco Nexus 1000V Password Recovery Guide
Cisco NX-OS System Messages Reference
Virtual Services Appliance Documentation
The Cisco Nexus Virtual Services Appliance (VSA) documentation is available at
http://www.cisco.com/en/US/products/ps9902/tsd_products_support_series_home.html
Virtual Security Gateway Documentation
The Cisco Virtual Security Gateway documentation is available at
http://www.cisco.com/en/US/products/ps13095/tsd_products_support_series_home.html
Virtual Network Management Center
The Cisco Virtual Network Management Center documentation is available at
http://www.cisco.com/en/US/products/ps11213/tsd_products_support_series_home.html
Virtual Wide Area Application Services (vWAAS)
The Virtual Wide Area Application Services documentation is available at
http://www.cisco.com/en/US/products/ps6870/tsd_products_support_series_home.html
ASA 1000V Cloud Firewall
The ASA 1000V Cloud Firewall documentation is available at
http://www.cisco.com/en/US/products/ps12233/tsd_products_support_series_home.html

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Preface
Obtaining Documentation and Submitting a Service Request
For information on obtaining documentation, submitting a service request, and gathering additional
information, see the monthly What’s New in Cisco Product Documentation, which also lists all new and
revised Cisco technical documentation, at:
http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html
Subscribe to the What’s New in Cisco Product Documentation as a Really Simple Syndication (RSS) feed
and set content to be delivered directly to your desktop using a reader application. The RSS feeds are a free
service and Cisco currently supports RSS Version 2.0.

CHAPTER
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1
Overview of Troubleshooting
This chapter introduces the basic concepts, methodology, and general troubleshooting guidelines for
problems that may occur when configuring and using Cisco Nexus 1000V.
This chapter includes the following sections:
•Overview of the Troubleshooting Process, page 1-1
•Overview of Best Practices, page 1-1
•Troubleshooting Basics, page 1-2
•Overview of Symptoms, page 1-4
•System Messages, page 1-4
•Troubleshooting with Logs, page 1-6
•Cisco Support Communities, page 1-7
•Contacting Cisco or VMware Customer Support, page 1-7
Overview of the Troubleshooting Process
To troubleshoot your network, follow these general steps:
Step 1 Gather information that defines the specific symptoms.
Step 2 Identify all potential problems that could be causing the symptoms.
Step 3 Systematically eliminate each potential problem (from most likely to least likely) until the symptoms
disappear.
Overview of Best Practices
Best practices are the recommended steps you should take to ensure the proper operation of your
network. We recommend the following general best practices for most networks:
•Maintain a consistent Cisco Nexus 1000V release across all network devices.
•Refer to the release notes for your Cisco Nexus 1000V release for the latest features, limitations,
and caveats.

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Chapter 1 Overview of Troubleshooting
Troubleshooting Basics
•Enable system message logging. See the “Overview of Symptoms” section on page 1-4.
•Verify and troubleshoot any new configuration changes after implementing the change.
Troubleshooting Basics
This section introduces questions to ask when troubleshooting a problem with Cisco Nexus 1000V or
connected devices. Use the answers to these questions to identify the scope of the problem and to plan
a course of action.
This section includes the following topics:
•Troubleshooting Guidelines, page 1-2
•Gathering Information, page 1-2
•Verifying Ports, page 1-3
•Verifying Layer 2 Connectivity, page 1-3
•Verifying Layer 3 Connectivity, page 1-3
Troubleshooting Guidelines
By answering the questions in the following subsections, you can determine the paths you need to follow
and the components that you should investigate further.
Answer the following questions to determine the status of your installation:
•Is this a newly installed system or an existing installation? (It could be a new host, switch, or
VLAN).
•Has the host ever been able to see the network?
•Are you trying to solve an existing application problem (too slow, too high latency, excessively long
response time) or did the problem show up recently?
•What changed in the configuration or in the overall infrastructure immediately before the
applications started to have problems?
To discover a network problem, use the following general network troubleshooting steps:
Step 1 Gather information on problems in your system. See the “Gathering Information” section on page 1-2.
Step 2 Verify the layer 2 connectivity. See the “Verifying Layer 2 Connectivity” section on page 1-3.\
Step 3 Verify the configuration for your end devices (storage subsystems and servers).
Step 4 Verify end-to-end connectivity. See the “Verifying Layer 3 Connectivity” section on page 1-3.
Gathering Information
This section highlights the tools that are commonly used to troubleshoot problems within your network.
These tools are a subset of what you may use to troubleshoot your specific problem.
Each chapter in this guide may include additional tools and commands specific to the symptoms and
possible problems covered in that chapter.