Home > Articles > Certification > Cisco Certification

Cisco Gateway Load Balance Protocol (GLBP) Configuration Process and Commands

  • Oct 9, 2013
In this article, networking consultant Sean Wilkins takes the concepts covered in his earlier "Introduction to GLBP" article and discusses how those concepts can be applied to real devices.
Like this article? We recommend

Like this article? We recommend

CCNA Routing and Switching 200-120 Network SimulatorCCNA Routing and Switching 200-120 Network Simulator

Learn More Buy

Like this article? We recommend

Like this article? We recommend

CCNA Routing and Switching 200-120 Network SimulatorCCNA Routing and Switching 200-120 Network Simulator

Learn More Buy

The configuration of Gateway Load Balancing Protocol (GLBP) is very similar to that of Hot Standby Router Protocol (HSRP) and Virtual Router Redundancy Protocol(VRRP), and like them is not overly complex to initially configure and use the default settings. This section will first go over the configuration process steps and commands that are used to perform a basic GLBP configuration. An example will then be shown on how these steps can be used to configure GLBP in a sample networking topology.

GLBP Simple Configuration Steps

Like HSRP and VRRP, only a few commands are used to configure GLBP using the default settings. Table 1 shows the common commands that are used to configure basic GLBP as well a few of the most commonly used commands to alter GLBP’s behavior.

Table 1 - VRRP Configuration Commands

1

Enter privileged EXEC mode

router>enable

2

Enter global configuration mode

router#configure terminal

3

Enter interface configuration mode

router(config)#interface interface

4

Configure an IP address on the interface

router(config-if)#ip address address netmask

5

Configure an GLBP virtual IP address

Notes:

The group-number can be any value from 1 to 1023.

This address (if entered) must be in the same subnet as the interface IP address (primary or secondary). It is possible not to enter an ip-address; in this case, the virtual IP address is learned from another GLBP device.

router(config-if)#glbp group-number ip [ip-address]

6

Configure the GLBP priority (optional)

Note: The valid values for the priority are from 1 through 255.

router(config-if)#glbp group-number priority priority

7

Configure GLBP preemption (optional)

Note: GLBP preemption is disabled by default.

router(config-if)#glbp group-number preempt

VRRP Simple Example

This section covers a simple example of how GLBP can be configured in a basic common topology. Figure 1 displays a common topology that exists in many networks that would potentially use a First Hop Redundancy Protocol (FHRP) like HSRP, VRRP, or GLBP. In this case, both R1 and R2 connect to a common subnet where hosts reside; this is the same interface used by GLBP to communicate with the other GLBP devices.

Figure 1 GLBP example topology

Tables 2 and 3 show the basic commands that are required to configure GLBP between the two devices shown in Figure 1.

The configuration will perform the following:

  • Configure the IP addresses 172.16.1.1/24 (R1) and 172.16.2.1 (R2) on their Fa0/0 interfaces
  • Configure GLBP between R1 and R2 using the IP addresses 10.10.10.1/24 (R1) and 10.10.10.2/24(R2) and a virtual IP address of 10.10.10.5 on their Fa1/0 interfaces

Table 2 - R1 Simple Example Configuration

1

Enter privileged EXEC mode.

R1>enable

2

Enter global configuration mode.

R1#configure terminal

3

Enter interface configuration mode.

R1(config)#interface fa0/0

4

Configure an IP address on the interface.

R1(config-if)#ip address 172.16.1.1 255.255.255.0

5

Enter interface configuration mode.

R1(config)#interface fa0/1

6

Configure an IP address on the interface.

R1(config-if)#ip address 10.10.20.1 255.255.255.252

7

Enter interface configuration mode.

R1(config)#interface fa1/0

8

Configure an IP address on the interface.

R1(config-if)#ip address 10.10.10.1 255.255.255.0

9

Configure GLBP using a virtual IP address of 10.10.10.5 using group 1.

R1(config-if)#glbp 1 ip 10.10.10.5

Table 3 - R2 Simple Example Configuration

1

Enter privileged EXEC mode.

R2>enable

2

Enter global configuration mode.

R2#configure terminal

3

Enter interface configuration mode.

R2(config)#interface fa0/0

4

Configure an IP address on the interface.

R2(config-if)#ip address 172.16.2.1 255.255.255.0

5

Enter interface configuration mode.

R2(config)#interface fa0/1

6

Configure an IP address on the interface.

R2(config-if)#ip address 10.10.20.2 255.255.255.252

7

Enter interface configuration mode.

R2(config)#interface fa1/0

8

Configure an IP address on the interface.

R2(config-if)#ip address 10.10.10.2 255.255.255.0

9

Configure GLBP using a virtual IP address of 10.10.10.5 using group 1.

R2(config-if)#glbp 1 ip 10.10.10.5

GLBP Complex Configuration Steps

In this section, the commands that are covered will extend to those that modify the default behavior of the GLBP process. These include GLBP timers (hello, hold, redirect and timeout), altering the default load balancing behavior (the default is round robin), configuring GLBP authentication, and basic interface tracking. Table 4 covers all the commands that are required to perform these steps.

Table 4 - GLBP Complex Configuration Commands

1

Configure the GLBP hello and hold timers.

router(config-if)#glbp group-number timers [msec] hello-timer [msec] hold-timer

2

Configure the GLBP redirect timers.

Note: The redirect-timeris the amount of time that passes before the AVG assumes that the forwarder is not going to return; the timeout is the amount of time until the virtual MAC address that was used by the failed AVF is no longer functional.

router(config-if)#glbp group-number timers redirect redirect-timer timeout

 

 

 

1

Configure the GLBP load balancing behavior.

router(config-if)#glbp group-number load-balancing [host-dependent | round-robin | weighted]

 

 

 

1

Configure GLBP Authentication.

router(config-if)#glbp group-number authentication {text plain-text-string | md5 {key-string keystring | key-chain key-chain-name}}

 

If a key-chain is configured with the command above, follow these next few steps to create the key-chain.

 

2

Create and enter into key chain configuration mode.

router(config)#key chain chain-name

3

Create and enter into key chain – key configuration mode.

Note: The key-numbercan be any number between 0-2147483647.

router(config-keychain)#key key-number

4

Enter the key string that will be used to authenticate with neighboring devices.

router(config-keychain-key)#key-string keystring

 

 

 

1

Configure GLBP Object tracking.

Note: The default priority decrement value is 10.

router(config-if)#glbp group-number track object-number [decrement priority]

2

(Optional) Configure the GLBP weighting values.

Note: With GLBP, each of the Active Virtual Forwarders (AVF) is assigned a weight (default is 100); if the defaults are not altered, then each of the AVFs will be equally loaded.

rsouter(config-if)#glbp group-number weighting weight [lower lower] [upper upper]

3

Create a tracked object.

Notes:

The object-numbercan be any number between 1 and 1000.

The line-protocolparameter will track the protocol state of the configured interface. The ip routingparameter will track the IP routing capability of an interface (is it configured with an IP address and operational?).

router(config)#track object-number interface interface {line-protocol | ip routing}

GLBP Complex Example

In this section, the configuration is extended to show basic GLBP authentication using key chains, altering the default load balancing behavior to weighting, and basic interface (line protocol) tracking. See Tables 5 and 6 for examples.

Table 5 - R1 Complex Example Configuration Addition

1

Enter privileged EXEC mode.

R1>enable

2

Enter global configuration mode.

R1#configure terminal

3

Create a key chain using the name testchain and enter into key chain configuration mode.

R1(config)#key chain testchain

4

Create and enter into key chain – key configuration mode using a key number of 1.

R1(config-keychain)#key 1

5

Enter a key string of test-string.

R1(config-keychain-key)#key-string test-string

6

Enter interface configuration mode.

R1(config-keychain-key)#interface fa1/0

7

Enable GLBP authentication using the configured key chain and group number of 1

R1(config-if)#glbp 1 authentication key-chain testchain

8

Change the default GLBP load balancing behavior to using weighting.

R1(config-if)#glbp 1 load-balancing weighted

9

Exit into global configuration mode.

R1(config-if)#exit

10

Create a tracked object that will monitor the line protocol status of the fa0/0 interface using an object number of 1.

R1(config)#track 1 interface fa0/0 line-protocol

11

Enter interface configuration mode.

R1(config)#interface fa1/0

12

Configure GLBP to use the tracked object to influence its weighting.

R1(config-if)#glbp 1 track 1 decrement 50

Table 6 - R2 Complex Example Configuration Addition

1

Enter privileged EXEC mode.

R2>enable

2

Enter global configuration mode.

R2#configure terminal

3

Create a key chain using the name testchain and enter into key chain configuration mode.

R2(config)#key chain testchain

4

Create and enter into key chain – key configuration mode using a key number of 1.

R2(config-keychain)#key 1

5

Enter a key string of test-string.

R2(config-keychain-key)#key-string test-string

6

Enter interface configuration mode.

R2(config-keychain-key)#interface fa1/0

7

Enable GLBP authentication using the configured key chain and group number of 1.

R2(config-if)#glbp 1 authentication key-chain testchain

8

Change the default GLBP load balancing behavior to using weighting.

R2(config-if)#glbp 1 load-balancing weighted

9

Exit into global configuration mode.

R2(config-if)#exit

10

Create a tracked object that will monitor the line protocol status of the fa0/0 interface using an object number of 1.

R2(config)#track 1 interface fa0/0 line-protocol

11

Enter interface configuration mode.

R2(config)#interface fa1/0

12

Configure GLBP to use the tracked object to influence its weighting.

R2(config-if)#glbp 1 track 1 decrement 50

Summary

The expectation of full-time connectivity has certainly gotten considerably higher over the last decade. Because of this, a number of different technologies have been developed to provide redundancy at every point within the network. As one of these, FHRPs are used to provide redundancy; which one you use depends on the specific deployment and the vendors that will be used within the target network. I hope that this article provided some insight into the configuration steps that are required to configure GLBP and get it up and running.

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