Home > Articles

VTP Concepts and Configuration

This article takes a look at Cisco’s VLAN Trunk Protocol (VTP), how it operates and how it can be configured on Cisco equipment to lower the administrative burden of network engineers/administrators.
Like this article? We recommend

One of the many things to master as a network engineer/administrator is the ability to optimize different job tasks. The easier and quicker it is to perform a specific task, the more time can be spent on more pressing issues. When administering a large switched network, one of the tasks that can take a lot of time is setting up separate VLANs across each of the switches. This article takes a look at Cisco’s VLAN Trunk Protocol (VTP), how it operates, and how it can be configured on Cisco equipment to lower the administrative burden of network engineers/administrators.

VLAN Trunk Protocol Concepts

In a network without the use of VTP, when an administrator wants to make configuration changes to global VLANs on the network, each VLAN would need to be manually configured on each individual switch. A method of reducing this administrative burden is to use Cisco’s proprietary VTP. VTP allows a VLAN to be added, configured or deleted on one VTP server switch; this switch will then replicate these actions out to all other supporting VTP switches. Using this method, VLAN configuration changes only need to be completed once, making the administration of global VLANs much less burdensome.

There are three versions of VTP available; versions 1 and 2 are very similar with the only difference being that version 2 adds support for token ring networks. Version 3 is newer and is only available on CatOS 8.1 and higher devices and will not be covered in this article as it is not as common.

Each VTP device is given a specific role or mode, these different modes include:

  • Server—A device that is in VTP server mode is able to add, configure and delete VLANs as well as set a number of different configuration parameters including VTP version, pruning and authentication settings.
  • Client—A device that is in VTP client mode is not able to make any changes to the VLAN database; it simply takes the database and implements it as dictated by the devices in VTP server mode.
  • Transparent—A device that is in VTP transparent mode does not participate in VTP at all; they do, however, forward VTP advertisements across the network.

VTP requires the use of either IEEE 802.1q VLAN trunking or Cisco’s Inter-Switch Link (ISL) trunking, which are used to transmit VTP advertisements between supporting switches. VTP keeps track of the most up-to-date VLAN configuration changes by using a configuration revision number. The switch advertising a change with the highest revision number is considered to be the most recent change and is used to change the VTP configuration of VTP supported switches. Since VTP devices assume that this advertisement with the highest revision number is a valid change, it is possible for an administrator to mistakenly bring a new switch into the network that has a higher revision number from a previously attached network. This event can alter the configuration of every supporting VTP device; ensure that any new switch being inserted into an existing switched VTP supported network have a cleared configuration and a lower configuration revision number then the current switched network.

A couple of different configuration elements must match for VTP devices to communicate and be integrated into the VTP network. These different elements include a VTP domain name and the VTP password (if one exists). VTP supports authentication using the VTP password, a hash of this password using MD5 is then created and inserted into VTP advertisements.

VLAN Trunk Protocol Configuration

The configuration of VTP is rather simple. By default, most Cisco IOS devices are in VTP server mode with no configured VTP domain name. New devices will automatically join (the first VTP network that is communicates with) an existing adjacent VTP network if no VTP password is set.

VLAN Trunk Protocol Configuration Commands

The following are the common configuration commands used for VTP:

  • The vtp mode server command is used to configure a Cisco IOS device as a VTP server.
  • The vtp mode client command is used to configure a Cisco IOS device as a VTP client.
  • The vtp mode server command is used to configure a Cisco IOS device to be VTP transparent and to pass VTP advertisements.
  • The vtp domain domain-name command is used to set the VTP domain name of a Cisco IOS device. The domain-name is case sensitive and can be up to 32 characters in length.
  • The vtp password password command is used to set the VTP password of a Cisco IOS device. The password is case sensitive and can be up to 32 characters in length.
  • The vtp version 2 command is used to set the version of VTP to version 2. This is typically only used when support for a token ring network is required.

VLAN Trunk Protocol Configuration Examples

Both of the examples that are shown in this section will use the same topology as shown in Figure 1 below:

Figure 1 VTP Configuration Example Topology

The first example depicts how to configure SW1, SW2 and SW3 to support VTP using a domain name of ‘CisCo’.

Table 1 VTP Configuration Example 1

1

Enter global configuration mode.

switch#configure terminal

2

Configure the switch with a VTP domain name of ‘CisCo’.

switch(config)#vtp domain CisCo

Repeat these steps on SW1, SW2 and SW3.


The second example depicts how to configure a VTP network using the domain name ‘CisCo’, a password of ‘Password’ and by making SW2 transparent.

Table 2 VTP Configuration Example 2

1

Enter global configuration mode.

switch#configure terminal

2

Configure the switch with a VTP domain name of ‘CisCo’.

switch(config)#vtp domain CisCo

3

Configure the switch with a VTP password of ‘Password’.

switch(config)#vtp password Password

Repeat these steps on SW1 and SW3.

 
  

1

Enter global configuration mode.

switch#configure terminal

2

Configure the switch to be VTP transparent.

switch(config)#vtp mode transparent

Repeat these steps on SW2.


Summary

While the use of VTP is restricted to Cisco devices, is has been configured on many networks since its creation. Many modern networks are moving away from the use of global VLANs on the network in exchange for routing at the access layer verus switching. Knowing the VTP concepts are still quite important as it has been deployed in a number of networks and should be familiar to any good Cisco network engineer.

Pearson IT Certification Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Pearson IT Certification and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Pearson IT Certification products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.pearsonitcertification.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020