Home > Articles > Certification > Cisco Certification

Introduction to the Cisco Virtual Router Redundancy Protocol (VRRP)

In this article, networking consultant Sean Wilkins looks at the Virtual Router Redundancy Protocol (VRRP), which is a standards-based version of Cisco’s Hot Standby Redundancy Protocol (HSRP). Wilkins specifically looks at VRRP and how it operates, along with the main concepts that should be known before attempting to configure it.
Like this article? We recommend

Often one of the least redundant parts of a network is the first hop between a host and the rest of the network. This is because they are typically configured with a default gateway IP address that links to a single device. Should this device fail, then all of the users on a specific segment who are using it as their default gateway will be unable to reach any other subnet including the Internet.

There are a number of different solutions to this problem; most of these are all grouped together and referred to as First Hop Redundancy Protocols (FHRP). This article looks at the Virtual Router Redundancy Protocol (VRRP), which is a standards-based version of Cisco’s Hot Standby Redundancy Protocol (HSRP). This article specifically looks at VRRP, how it operates, along with the main concepts that should be known before attempting to configure it. Another VRRP configuration article follows with the details of how to configure VRRP.

How Does VRRP Work?

The basic concepts behind both HSRP and VRRP are very similar, and are intended to deal with a basic redundancy problem that exists on many local area networks (LAN) that are used everyday—that is, the single point of failure that is inherent when using a single default gateway for hosts on the network. In many common networks, the hosts that exist on the LAN are configured with a default gateway to access devices that are not located on the local network (in a different subnet); this gateway that is used is another name that is used to refer to a router. This router has a list of its known networks, and is further configured with a routing table that enables it to handle traffic to and from multiple sources and destinations. However, if this router were to go down or be taken offline, then all of those devices that use it as their default gateway will be unable to access outside networks.

FHRPs deal with this problem by offering redundancy solutions; VRRP and HSRP offer similar solutions with a few major differences. VRRP is a standards-based solution, whereas HSRP is Cisco proprietary and is (for the most part) only supported on Cisco devices. VRRP offers the ability use multiple (more than 2) routers for redundancy; HSRP is limited to a single active (forwards traffic) and standby (waits to forward traffic when the active device goes down). VRRP also differs in some of its default settings, namely that master (active) device preemption is enabled by default.

VRRP communicates with the other configured VRRP routers (within the same group) by sending an advertisement out every second (by default); this advertisement provides these devices with a state of the current master router as well as its priority. VRRP uses the IPv4 multicast address 224.0.0.18 for these advertisements.

VRRP (like HSRP) also supports the ability to configure multiple VRRP virtual router instances on a single physical interface (up to 255); this enables a device to be configured into load sharing configurations.

VRRP Priority and Preemption

When VRRP is configured on a network, the concepts of priority and preemption are important to understand for VRRP to work as expected. By default, the priority of a VRRP router is 100 out of a priority range that goes from 1 through 254; the higher the priority, the higher the chance the device will become the master (forwarding) VRRP device. If there is a tie in the VRRP priority, then the device with the higher IP addresses of the devices will be used as a tiebreak.

Preemption (as it is enabled by default) allows any new device that comes onto a network with other VRRP configured routers to become the master router immediately, should it have a higher priority. Without preemption enabled, this device would need to wait until the master device failed for it to take over as the master.

VRRP Authentication

VRRP offers a number of authentication options as well to ensure that the infrastructure running VRRP is protected from malicious attacks. By default, VRRP is configured with no authentication, and any device configured onto the same VRRP group can affect the behavior of VRRP. There are two further authentication options: plaintext authentication and MD5 authentication (using a MD5 key string or MD5 key chain). The MD5 choice is the only real option on a production network.

VRRP Object Tracking

Like HSRP, VRRP supports the ability to alter device priority, depending on the state of a currently configured track object. At its most basic, this object can track the line protocol state or IP configuration state of an interface and go up or down depending on these states (specific states can be tracked using Cisco’s IP SLA feature). Once configured, the VRRP group process will continue to pool the track object for its status. If it is down, it can be configured to alter the priority of a specific VRRP device, which can affect the current device that is being selected as the master router.

Summary

If the reader has come off reading an HSRP article or has some experience with HSRP, it should be obvious that both HSRP and VRRP are very similar and follow the same general rules. There are two big differences that affect the selection of one over the other: whether all of the implemented devices are Cisco, and whether more than two devices are ever going to be configured onto a single LAN segment.

If all of the current (or future) devices are not Cisco, then the selection of VRRP is easy, as (for the most part) HSRP is only widely supported on Cisco equipment, whereas VRRP is a standards-based solution and is supported by many different vendors. The other difference may not be that big of a deal on many networks because most don’t have multiple routers that are connected to a single LAN segment. HSRP supports an active and standby device, which is typically enough to satisfy the requirements of obtaining enough redundancy. However, VRRP does support more than two devices, and this can be helpful in those situations where multiple (more than two) are connected to the same LAN segment.

Ultimately, the use of one of the FHRPs (generally) is a good common practice on LAN segments that require high uptime and where outages can be costly.  I hope that this article will help in making the selection of which one to select when the decision needs to be made (or helps those trying to understand the VRRP concepts for testing purposes).

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT 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 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 InformIT. 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.informit.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