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Manual Chapter: BIG-IP GTM Configuration
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About listeners

A listener is a specialized virtual server that uses port 53 and to which you assign a specific IP address. When a DNS name resolution request is sent to the IP address of a listener, BIG-IP GTM either handles the request locally or forwards the request to the appropriate resource.

How listeners process network traffic

You control how BIG-IP GTM responds to DNS name resolution requests on a per-listener basis. The number of listeners you create depends on your network configuration and the destinations to which you want to send specific requests. For example, a single BIG-IP GTM can be the primary authoritative server for one domain, while forwarding other DNS name resolution requests to a different DNS server. BIG-IP GTM always manages and responds to DNS name resolution requests for the wide IPs that are configured on the BIG-IP GTM.

Consider the fictional company SiteRequest, once integrated into the network, BIG-IP GTM is responsible for:
  • Managing and responding to requests for two wide IPs configured on the external VLAN:
    • www.siterequest.com
    • downloads.siterequest.com
  • Forwarding DNS traffic destined for the existing DNS server at IP address 10.2.5.37

In this scenario, the Global Traffic Manager requires two listeners:

  • A listener with an IP address that is on an external VLAN to manage DNS traffic destined for the wide IPs.
  • A listener with an IP address of a local DNS server 10.2.5.37 to forward incoming traffic destined for that server.
Listener configuration example
Listener configuration example

About wildcard listeners

A wildcard listener is a special listener that is assigned an IP address of 0.0.0.0 and the DNS query port (port 53). When you want BIG-IP GTM to respond to DNS name resolution requests coming into your network, regardless of the destination IP address of the given request, you create a wildcard listener. BIG-IP GTM responds not only to wide IP requests, but also forwards other DNS name resolution requests to other DNS servers.

About Prober pools

A Prober pool is an ordered collection of one or more BIG-IP® systems. BIG-IP Global Traffic Manager™ (GTM™) can be a member of more than one Prober pool, and a Prober pool can be assigned to an individual server or a data center. When you assign a Prober pool to a data center, by default, the servers in that data center inherit that Prober pool.

The members of a Prober pool perform monitor probes of servers to gather data about the health and performance of the resources on the servers. BIG-IP GTM makes load balancing decisions based on the gathered data. If all of the members of a Prober pool are marked down, or if a server has no Prober pool assigned, BIG-IP GTM reverts to a default intelligent probing algorithm to gather data about the resources on the server.

This figure illustrates how Prober pools work. BIG-IP GTM contains two BIG-IP Local Traffic Manager™ (LTM™) systems that are assigned Prober pools and one BIG-IP LTM system that is not assigned a Prober pool:

Example illustration of how Prober pools work BIG-IP systems with prober pools
Prober Pool 1 is assigned to a generic host server
BIG-IP LTM3 is the only member of Prober Pool 1, and performs all HTTPS monitor probes of the server.
Prober Pool 2 is assigned to generic load balancers
BIG-IP LTM1 and BIG-IP LTM2 are members of Prober Pool 2. These two systems perform HTTP monitor probes of generic load balancers based on the load balancing method assigned to Prober Pool 2.
The generic load balancers on the left side of the graphic are not assigned a Prober pool
BIG-IP GTM can solicit any BIG-IP system to perform FTP monitor probes of these load balancers, including systems that are Prober pool members.

About Prober pool statistics

You can view the number of successful and failed probe requests that the BIG-IP® GTM™ system (on which you are viewing statistics) made to the Prober pools. These statistics reflect only the number of Probe requests and their success or failure. These statistics do not reflect the actual probes that the pool members made to servers on your network.

Prober pool statistics are not aggregated among the BIG-IP GTM systems in a synchronization group. The statistics on one BIG-IP GTM include only the requests made from that BIG-IP GTM system.

In this figure, the Prober pool statistics that display on BIG-IP GTM1 are the probe requests made only by that system.

Prober pool statistics displayed per system Prober pool statistics displayed per system

About Prober pool status

The status of a Prober pool also indicates the status of the members of the pool. If at least one member of a Prober pool has green status (Available), the Prober pool has green status.

The status of a Prober pool member indicates whether the BIG-IP GTM system, on which you are viewing status, can establish an iQuery connection with the member.

Note: If a Prober pool member has red status (Offline), no iQuery connection exists between the member and the BIG-IP GTM system on which you are viewing status. Therefore, that BIG-IP GTM system cannot request that member to perform probes, and the Prober pool will not select the member for load balancing.

About probes

A probe is an action a BIG-IP system takes to acquire data from other network resources. BIG-IP Global Traffic Manager (GTM) uses probes to track the health and availability of network resources.

About GTM probes of an LDNS

BIG-IP® Global Traffic Manager™ (GTM™) is responsible for acquiring data from local DNS servers (LDNS) using probes. Unlike probes conducted on internal systems, such as web servers, probes of an LDNS require that BIG-IP GTM verifies data from a resource that exists outside the network. Typically, this data is the path information BIG-IP GTM requires when conducting Quality of Service, Round Trip Time, Completion Rate, and Hops load balancing methods.

Flow of probe process Flow of probe process

The steps in the probe process

  1. An LDNS sends a DNS name resolution request to BIG-IP GTM for a wide IP.
  2. The specific BIG-IP GTM in a synchronization group that is chosen to manage probing of a resource creates an entry with a state of New (unless an entry for the LDNS already exists).
    Note: Once a specific BIG-IP GTM system becomes responsible for managing the probing of a resource, that BIG-IP GTM maintains that responsibility until that GTM goes offline, a new BIG-IP GTM is added to the data center, or the configuration of the resource changes.
  3. The BIG-IP GTM that is responsible for managing the probing of the resource, delegates the probe to a BIG-IP GTM that is currently responsible for conducting the fewest number of probes.
    Note: BIG-IP GTM checks this statistic each time a probe of a specific resource is required; as a result, the BIG-IP GTM that probes the resource can change from one probe instance another.
  4. The big3d agent on the BIG-IP GTM that is delegated to probe the resource, sends a probe to the LDNS.
  5. The LDNS responds to the probe.
  6. BIG-IP GTM updates the LDNS entry, assigning it an Active state.
  7. The big3d agent then broadcasts the results of the probe to all BIG-IP GTM systems in the synchronization group.

Converting a statistics collection server to a Prober pool automatically

In version 10.2 of BIG-IP® Global Traffic Manager™ (GTM™), you could assign a single BIG-IP® system to probe a server to gather health and performance data. You did this by specifying the IP address of the BIG-IP system (which you chose to perform probes of the server) in the Statistics Collection Server field of the server. In version 11.0, this feature was replaced by the Prober pool feature.

When you upgrade from version 10.2.x to version 11.x, if a single BIG-IP system was assigned to probe a server, BIG-IP GTM converts the single server to a Prober pool with one member, and then assigns the Prober pool to the server to which the Statistics Collection server was originally assigned. The name of the new Prober pool is based on the IP address of the original Statistics Collection server. If the original Statistics Collection server had an IP address of 10.10.2.3, the name of the automatically created Prober pool is prober_pool_10_10_2_3.

About delegation of LDNS probes

By default, BIG-IP GTM delegates the probe of a resource to a BIG-IP GTM that is in the same data center as the resource, because the close proximity improves probe response time. However, when more than one BIG-IP GTM in a synchronization group resides in the same data center, an algorithm is used to delegate the probes of resources equally among those BIG-IP GTM systems. This ensures that no BIG-IP GTM becomes overloaded with conducting probes, which can cause a decrease in the performance of the other tasks for which the BIG-IP system is responsible. When a data center does not contain a BIG-IP GTM, an algorithm is used to distribute the actual probes of a resource in that data center equally among the BIG-IP GTM systems in the synchronization group.

About LDNS entries on a GTM

An LDNS entry can be in one of three states: New, Pending, or Active. In general, the New and Pending states are temporary. An LDNS entry remains in one of these states only until the LDNS responds to the first probe request from a BIG-IP GTM.

New
This LDNS has not contacted BIG-IP GTM before.
Pending
This LDNS has contacted BIG-IP GTM before; however, this LDNS has yet to respond to a probe.
Active
BIG-IP GTM has an entry for this LDNS.

Protocols and ports used by big3d during communications with local DNS servers

This table describes the protocols and ports the big3d agent uses to communicate with an LDNS when collecting path data for the local DNS servers.

Table 1. Communication between big3d agents and local DNS servers
From To Protocol From port To port Purpose
big3d agent LDNS ICMP n/a n/a Probe using ICMP pings
big3d agent LDNS TCP >1023 53 Probe using TCP (Cisco routers: allow establish)
LDNS big3d agent TCP 53 1023 Replies using TCP (Cisco routers: allow establish)
big3d agent LDNS UDP 53 33434 Probe using UDP or the traceroute utility
LDNS big3d agent ICMP n/a n/a Replies to ICMP, UDP pings, or traceroute utility probes
big3d agent LDNS dns_rev, dns_dot >1023 53 Probe using DNS rev or DNS dot
big3d agent LDNS dns_rev, dns_dot 53 >1023 Replies to DNS rev or DNS dot probes

About wide IPs

A wide IP maps a fully-qualified domain name (FQDN) to one or more pools of virtual servers that host the content of a domain. When an LDNS issues a DNS name resolution for a wide IP, the configuration of the wide IP indicates which pools of virtual servers are eligible to respond to the request, and which load balancing methods BIG-IP GTM uses to select the pool.

About wildcard characters in wide IP names

BIG-IP Global Traffic Manager (GTM) supports these wildcard characters in wide IP names and aliases:

Question mark (?)
Use to replace a single character, except a dot (.).
Asterisk (*)
Use to replace multiple consecutive characters with the exception of dots (.)

You can use one or more question marks or asterisks, or both question marks and asterisks in a wide IP name or alias.

Valid uses of wildcard characters for the wide IP name www.mydomain.net include:
  • ???.mydomain.net
  • www.??.domain.net
  • www.my*.net
  • www.??*.net
  • www.my*.*
  • ???.my*.*
  • *.*.net
  • www.*.??

Using wildcard characters in wide IPs to minimize maintenance tasks

Determine the domain names and aliases for which you want to configure wide IPs.
Create a wide IP using wildcard characters in the name to represent a domain when you have a large quantity of aliases that you want to use for the domain.
  1. On the Main tab, click Global Traffic > Wide IPs. The Wide IPs List screen opens.
  2. Click Create. The New Wide IP screen opens.
  3. In the Name field, type a name for the wide IP.
    Tip: You can use two different wildcard characters in the wide IP name: asterisk (*) to represent several characters and question mark (?) to represent a single character. This reduces the number of aliases you have to add to the configuration.
  4. From the Pool list, select the pools that this wide IP uses for load balancing. The system evaluates the pools based on the wide IP load balancing method configured.
    1. From the Pool list, select a pool. A pool can belong to more than one wide IP.
    2. Click Add.
  5. Click Finished.

About persistence connections

Most load balancing methods divide DNS name resolution requests among available pools or virtual servers. Each time BIG-IP GTM receives a request, it sends that request to the most appropriate resource based on the configuration of your network.

For example, when a user visits a web site, multiple DNS name resolution requests are generated as the user moves from page to page. Depending on the load balancing method configured, BIG-IP GTM sends each request to a different server, virtual server, or data center. In certain circumstances, you might want to ensure that a user remains with a given set of resources throughout the session. For example, a user attempting to conduct on online banking transaction needs to remain with the same set of resources to ensure that the transaction is completed successfully.

Configuring GTM for persistent connections

Configure BIG-IP GTM for persistent connections when you want a user to stay with a specific set or resources during a web transaction.
  1. On the Main tab, click Global Traffic > Wide IPs. The Wide IPs List screen opens.
  2. Click Create. The New Wide IP screen opens.
  3. In the Name field, type a name for the wide IP.
    Tip: You can use two different wildcard characters in the wide IP name: asterisk (*) to represent several characters and question mark (?) to represent a single character. This reduces the number of aliases you have to add to the configuration.
  4. From the Load Balancing Method list, select the load balancing method the wide IP uses to select a pool.
  5. On the menu bar, click Pools.
  6. From the Persistence list, select Enabled.
  7. In the Persistent TTL field, type the number of seconds the persistence entry is valid. This value can range from 0 to 4294967295 seconds.
  8. Click Finished.
Once a resource has sent a response to a DNS name resolution request, BIG-IP GTM sends subsequent requests from the same connection to that same resource until the current session is completed.

About wide IPs and a last resort pool

BIG-IP® Global Traffic Manager™ (GTM™) considers any pool associated with a wide IP as a potential resource to which to load balance DNS name resolution requests. A last resort pool is a pool of virtual servers to which BIG-IP GTM sends DNS name resolution requests in the event that all other pools associated with the wide IP are unavailable. When you design your network, ensure that this particular pool is kept in reserve and not used as part of the normal global server load balancing.

Configuring a wide IP with a last resort pool

Ensure that a pool of virtual servers that is not part of the normal global server load balancing operations exists in the configuration.
Create a wide IP to map a FQDN to one or more pools of virtual servers that host the content of the domain, and assign a last resort pool to the wide IP.
  1. On the Main tab, click Global Traffic > Wide IPs. The Wide IPs List screen opens.
  2. Click Create. The New Wide IP screen opens.
  3. In the Name field, type a name for the wide IP.
    Tip: You can use two different wildcard characters in the wide IP name: asterisk (*) to represent several characters and question mark (?) to represent a single character. This reduces the number of aliases you have to add to the configuration.
  4. From the Pool list, select the pools that this wide IP uses for load balancing. The system evaluates the pools based on the wide IP load balancing method configured.
    1. From the Pool list, select a pool. A pool can belong to more than one wide IP.
    2. Click Add.
  5. From the Last Resort Pool list, select a pool for the system to use when no other resources are available.
  6. Click Finished.
BIG-IP GTM uses the resources included in the last resort pool only if no other resources are available to handle DNS name resolution requests for the wide IP.

About data centers

All of the resources on your network are associated with a data center. BIG-IP® Global Traffic Manager™ (GTM™) consolidates the paths and metrics data collected from the servers, virtual servers, and links in the data center, and uses that data to conduct load balancing and route DNS name resolution requests to the best-performing site based on different factors. .

BIG-IP GTM might send all requests to one site when another site is down. Alternatively, BIG-IP GTM might send a request to the data center that has the fastest response time. A third option might be for BIG-IP GTM to send a request to the data center that is located closest to the client’s source address.
Tip: The resources associated with a data center are available only when the data center is also available.

About servers

A server defines a physical system on the network. Servers contain the virtual servers that are the ultimate destinations of DNS name resolution requests. BIG-IP® Global Traffic Manager™ (GTM™) supports three types of servers:

BIG-IP® systems
Any member of the BIG-IP system product line.
Third-party load balancing systems
A third-party load balancing system is any system, other than a BIG-IP system, that supports and manages virtual servers on the network.
Third-party host servers
A third-party host server is any server on the network that does not support virtual servers.
Important: At a minimum, you must define two servers, one that represents BIG-IP GTM and one that represents another managed server (either a load balancing or host server).

About third-party host servers

A host is a network resource that is not a part of the BIG-IP® product family and does not provide load balancing. BIG-IP® Global Traffic Manager™ (GTM™) supports these host servers:

  • CacheFlow®
  • NetApp™
  • Sun Solaris™
  • Windows 2000 Server (You can monitor the Windows Vista® Enterprise Server using the Windows 2000 Server.)
  • Windows NT 4.0™

About third-party load balancing servers

BIG-IP® Global Traffic Manager™ (GTM™) interacts with other load balancing servers to determine availability and assess performance when responding to DNS name resolution requests. BIG-IP GTM supports these load balancing servers:

  • Alteon® Ace Director
  • Cisco® CSS
  • Cisco® LocalDirector v2
  • Cisco® LocadDirector v3
  • Cisco® SLB
  • Extreme
  • Foundry® ServerIron
  • Radware WSD
  • Other generic load balancers

About virtual servers

A virtual server is a specific IP address and port number that points to a resource on the network. In the case of host servers, this IP address and port number likely point to the resource itself. With load balancing systems, such as the Local Traffic Manager™, virtual servers are often proxies that allow the load balancing server to manage a resource request across a multitude of resources.

Note: Load balancing servers, excluding Global Traffic Manager™ and Link Controller™ systems, contain at least one virtual server.

Configuring virtual server availability to be dependent on the status of other virtual servers

Ensure that multiple virtual servers are configured on the server. Determine the virtual servers upon which you want the availability of a virtual server to be dependent.
Configure a virtual server to be available based on the availability of other virtual servers by configuring a Dependency List for the virtual server.
  1. On the Main tab, click Global Traffic > Servers. The Server List screen opens.
  2. In the Server List, click a server name. The server settings and values display.
  3. On the menu bar, click Virtual Servers. A list of the virtual servers configured on the server displays.
  4. In the Virtual Servers list, click a virtual server name. The virtual server settings and values display.
  5. From the Configuration list, select Advanced. Additional controls display on the screen.
  6. In the Dependency List area, from the Virtual Servers list, select each virtual server on which you want the virtual server to be dependent, and then click Add. The virtual servers display in the list as you add them.
  7. Click Finished.
The virtual server is now available only when the virtual servers on the dependency list are also available.

Configuring virtual server status for clusters

You can configure virtual server status to be dependent only on the timeout value of the monitor associated with the virtual server. This ensures that when the primary blade in a cluster becomes unavailable, the gtmd agent on the new primary blade has time to establish new iQuery® connections with and receive updated status from other BIG-IP® systems.
Tip: The big3d agent on the new primary blade must be up and functioning within 90 seconds (the timeout value of the BIG-IP monitor).
  1. On the Main tab, click System > Configuration > Global Traffic > General. The General configuration screen opens.
  2. Select Depends on Monitors Only from the Virtual Server Status list.
  3. Click Update.

About pools and pool members

A pool is a collection of virtual servers that can reside on multiple servers. A virtual server is a combination of IP address and port number that points to a specific resource on the network. When you add a virtual server to a pool, it becomes a pool member. A pool member is a virtual server that has attributes that pertain to the virtual server only in the context of the pool. A virtual server can be a member of multiple pools and have different attributes in each pool. BIG-IP® Global Traffic Manager™ (GTM™) directs traffic to a pool member, based on the attributes of the pool member.

To illustrate the difference between pool members and virtual servers, consider the fictional company SiteRequest. In the London data center, the IT team has a virtual server that acts as a proxy for a BIG-IP Local Traffic Manager™ (LTM™). This virtual server is the primary resource for DNS name resolution requests for the company web page that originate from Europe. This virtual server is also the backup resource for requests that originate from the United States. Because these are two distinctly different roles, the virtual server is a pool member in two different pools. The IT team can use this configuration to customize the virtual server for each pool to which it belongs, without modifying the actual virtual server itself.

About CNAME records

A CNAME record specifies that a domain name is an alias of another domain. When you create a pool with a canonical name, BIG-IP GTM responds to DNS queries for the CNAME with the real fully qualified domain name (FQDN).

About links

A link is a logical representation of a physical device (router) that connects your network to the Internet. BIG-IP® Global Traffic Manager™ (GTM™) tracks the performance of links, which influence the availability of pools, data centers, wide IPs, and distributed applications.

Defining a link

Ensure that at least one data center exists in the configuration.

Gather information about the routers that you want to define as links, including:

  • IP addresses
  • Data center location
Define links to aid BIG-IP® Global Traffic Manager™ (GTM™) in determining resource availability.
  1. On the Main tab, expand Global Traffic, and click Links. The Links list screen opens.
  2. Click Create. The New Link screen opens.
  3. Type a name for the link.
    Important: Link names are limited to 63 characters.
  4. Specify whether the link uses address translation when communicating between the network and the Internet.
    Important: If you enable this setting, the BIG-IP Link monitor cannot monitor outbound traffic through this link.
  5. Type the IP address of a router in the Address field, and then click Add. You can add more than one IP address, depending on how the server on which you are creating the link interacts with the rest of your network.
  6. Select the data center where the router that the link represents resides.
  7. In the Uplink Address field, specify the IP address of the router on the ISP side of the link. When you configure an uplink address, the BIG-IP system sends SNMP requests to the IP addresses configured in the Router Address List. The system uses the statistics that the router returns to distinguish between internal-only traffic and traffic destined for the Internet.
  8. Assign the BIG-IP Link monitor to the link by moving it from the Available list to the Selected list.
  9. Click Create.
The big3d agent can now gather and analyze path and metrics information about outbound traffic passing through the router the link represents.

Load balancing outbound traffic through links of differing bandwidths

Ensure that at least one data center exists in the configuration.

Gather the following information about the routers that you want to define as links:

  • IP addresses
  • Data Center location
When you want to avoid sending too much outbound traffic to a router with lower bandwidth, configure the links that represent your routers for ratio weighting.
Important: You must use the same weighting option for all of the links on your network.
  1. On the Main tab, expand Global Traffic, and click Links. The Links list screen opens.
  2. Click Create. The New Link screen opens.
  3. Type a name for the link.
    Important: Link names are limited to 63 characters.
  4. Specify whether the link uses address translation when communicating between the network and the Internet.
    Important: If you enable this setting, the BIG-IP Link monitor cannot monitor outbound traffic through this link.
  5. Type the IP address of a router in the Address field, and then click Add. You can add more than one IP address, depending on how the server on which you are creating the link interacts with the rest of your network.
  6. Select the data center where the router that the link represents resides.
  7. In the Uplink Address field, specify the IP address of the router on the ISP side of the link. When you configure an uplink address, the BIG-IP system sends SNMP requests to the IP addresses configured in the Router Address List. The system uses the statistics that the router returns to distinguish between internal-only traffic and traffic destined for the Internet.
  8. From the Configuration list, select Advanced. Additional controls display on the screen.
  9. Assign the BIG-IP Link monitor to the link by moving it from the Available list to the Selected list.
  10. From the Weighting list, select Ratio, when you want BIG-IP to continuously check the performance of each link and route outbound traffic through the link with the best performance data.
  11. From the Weighting list, select the methodology BIG-IP uses to select a link through which to route outbound traffic.
    Option Description
    Ratio Specifies that BIG-IP uses the ratio you specify in the Link Ratio field when selecting a link.
    Price (Dynamic Ratio) Specifies that the system uses dynamic ratio methodology when selecting the link.
  12. If you selected Ratio from the Weighting list, in the Link Ratio field, type the frequency at which the system sends traffic through the link.
  13. Click Create.
The BIG-IP system can now load balance outbound traffic through your routers based on bandwidth.

Load balancing outbound traffic over the least expensive link first

Ensure that at least one data center exists in the configuration.

Gather the following information about the routers that you want to define as links:

  • IP addresses
  • Data Center location
When you want to load balance outbound traffic to a router with the lowest fees first, configure the links that represent your routers for price weighting.
Important: You must use the same weighting option for all of the links on your network.
  1. On the Main tab, expand Global Traffic, and click Links. The Links list screen opens.
  2. Click Create. The New Link screen opens.
  3. Type a name for the link.
    Important: Link names are limited to 63 characters.
  4. Specify whether the link uses address translation when communicating between the network and the Internet.
    Important: If you enable this setting, the BIG-IP Link monitor cannot monitor outbound traffic through this link.
  5. Type the IP address of a router in the Address field, and then click Add. You can add more than one IP address, depending on how the server on which you are creating the link interacts with the rest of your network.
  6. Select the data center where the router that the link represents resides.
  7. In the Uplink Address field, specify the IP address of the router on the ISP side of the link. When you configure an uplink address, the BIG-IP system sends SNMP requests to the IP addresses configured in the Router Address List. The system uses the statistics that the router returns to distinguish between internal-only traffic and traffic destined for the Internet.
  8. From the Configuration list, select Advanced. Additional controls display on the screen.
  9. Assign the BIG-IP Link monitor to the link by moving it from the Available list to the Selected list.
  10. From the Weighting list, select Price, when you want BIG-IP to direct outbound traffic through the link with the lowest cost first.
  11. Click Create.
The BIG-IP system can now load balance outbound traffic through your routers based on cost.

Configuring statistics to reflect link bandwidth usage

Your ISP providers must use duplex billing.

When you want the BIG-IP system to display statistics that reflect link bandwidth usage, configure duplex billing.
  1. On the Main tab, expand Global Traffic, and click Links. The Links list screen opens.
  2. Click a link name. The Links list screen opens.
  3. Select the Duplex Billing check box when the ISP that provides the link bills for bandwidth usage based on a maximum amount of inbound or outbound traffic (whichever is higher), rather than billing for bandwidth usage based on the total inbound and outbound traffic.
  4. Click Create. The Link List screen displays.

About distributed applications

A distributed application is a collection of one or more wide IPs, data centers, and links that serve as a single application to a web site visitor. Configuring a distributed application provides several advantages:

  • You can organize logical network components into groups that represent a business environment.
  • You can configure a distributed application to be dependent upon the availability of a data center, server, or link. This dependency ensures that a user cannot access a distributed application when a portion of the resources are unavailable.
  • You can define persistence for the distributed application, ensuring that a user, who accesses the distributed application uses the same resources during a single session.
If the New York data center goes offline, a wide IP in that data center becomes unavailable. A distributed application associated with that wide IP also becomes unavailable. Consequently, the system does not send resolution requests to any of the distributed application resources, until the entire application becomes available again.

About ZoneRunner

You can use the ZoneRunner™ utility to create and manage DNS zone files and configure the BIND instance on BIG-IP® Global Traffic Manager™ (GTM™). With the ZoneRunner utility, you can:

  • Import and transfer DNS zone files
  • Manage zone resource records
  • Manage views
  • Manage a local nameserver and the associated configuration file, named.conf
  • Transfer zone files to a nameserver
  • Import only primary zone files from a nameserver

About named.conf

named.conf contains the primary operational characteristics of BIND, including DNS views, access control list definitions, and zones. The ZoneRunner™ utility updates named.conf when you modify the local BIND instance.

Configuring named

Ensure that at least one zone is configured on BIG-IP GTM.
Use ZoneRunner to edit named.conf, to decrease the risk of a syntax error that prevents the BIND system from performing as expected. Zonerunner provides an automatic syntax check and displays error messages to help you write the correct syntax.
  1. On the Main tab, click Global Traffic > ZoneRunner > Named Configuration. The Named Configuration screen opens.
  2. In the Options field, type additional configurations per your network design.
  3. Click Update.

Creating a master DNS zone

A Master zone is authoritative. Create a zone when you want to use ZoneRunner to manage DNS zones and resource records.
Tip: The BIG-IP system can be either a primary or secondary DNS server.
  1. On the Main tab, click Global Traffic > ZoneRunner > Zone List. The Zone List screen opens.
  2. Click Create. The New Zone screen opens.
  3. From the View Name list, select external. The external view is a default view to which you can assign zones.
  4. In the Zone Name field, type a period character (.).
  5. From the Zone Type list, select Master.
  6. Clear the Zone File Name field, and type the zone file name. db.external.siterequest.com
    Note: Do not include a trailing dot.
  7. Click Finished.
If you want further help creating a custom zone file, see SOL8380 on Askf5.com for instructions.

Creating a hint zone

Hint zones designate a subset of the root nameservers list. When the local nameserver starts (or restarts), the nameserver queries the root servers in the hint zone for the most current list of root servers. The root hint is built into BIND version 9.0 and later.

Create a zone when you want to use ZoneRunner to manage DNS zones and resource records.

Tip: The BIG-IP system can be either a primary or secondary DNS server.
  1. On the Main tab, click Global Traffic > ZoneRunner > Zone List. The Zone List screen opens.
  2. Click Create. The New Zone screen opens.
  3. From the View Name list, select external. The external view is a default view to which you can assign zones.
  4. In the Zone Name field, type a period character (.).
  5. From the Zone Type list, select Hint.
  6. Clear the Zone File Name field, and type the zone file name. db.external.siterequest.com
    Note: Do not include a trailing dot.
  7. Click Finished.
If you want further help creating a custom hint file, see SOL8380 at Askf5.com for instructions.

Configuring a BIG-IP GTM to allow zone file transfers

By default, BIG-IP® GTM™ is configured to secure BIND to not allow zone transfers except from the localhost. However, you can configure BIG-IP GTM to allow zone file transfers to other DNS servers.
  1. On the Main tab, click Global Traffic > ZoneRunner > Named Configuration. The Named Configuration screen opens.
  2. In the Options field, modify the allow-transfer statement to include the IP address of the BIG-IP GTM. You can modify the following allow-transfer statement to use the IP address of the BIG-IP GTM. allow-transfer { localhost; 192.168.10.105; };
  3. On the menu bar, click View List. The View List screen opens.
  4. Click the name of the view that contains the zone you are configuring. The View Configuration screen opens.
  5. In the Options area, modify the match-clients statement based on your configuration.
    View configuration type Add to match-clients statement
    Single view configuration view "external" { match-clients { "zrd-acl-000-000"; any; };
    Multiple view configuration, where you want to allow transfers from BIG-IP GTM Modify the following match-clients statement to use the IP address of the BIG-IP GTM. acl "internal-acl" { <IP address> ; }; view "internal" { match-clients { "zrd-acl-000-001"; "internal-acl"; <IP address> ; }; view "external" { match-clients { "zrd-acl-000-000"; any; };
  6. Click Update.
To verify that zone transfers are working properly, run this Linux command on an external machine:dig @172.17.1.253 es.net. axfr

The command should return this response:

; <<>> DiG? 9.5.0-P2 <<>> @172.17.1.253 es.net. axfr ; (1 server found) ;; global options: printcmd es.net. 500 IN SOA sgtraining1.es.f5net.com. hostmaster.sgtraining1.es.f5net.com. 6 10800 3600 604800 60 es.net. 500 IN NS sgtraining1.es.f5net.com. a.es.net. 30 IN A 172.17.1.100 b.es.net. 30 IN A 172.18.1.100 es.net. 500 IN SOA sgtraining1.es.f5net.com. hostmaster.sgtraining1.es.f5net.com. 6 10800 3600 604800 60 ;; Query time: 6 msec ;; SERVER: 172.17.1.253#53(172.17.1.253) ;; WHEN: Fri Mar 11 17:20:25 2011 ;; XFR size: 5 records (messages 1, bytes 180)

About DNS views

A DNS view is a modification of a nameserver configuration based on the community attempting to access it. Using views, you can build multiple nameserver configurations on the same server, and have those configurations apply dynamically when the request originates from a specified source.

If your DNS handles requests from both inside and outside your company, you can create two views: internal and external.

Creating a DNS view

It is helpful to keep in mind that ZoneRunner contains a default view named external.
Create an additional DNS view to modify the local nameserver configuration to allow a specific community to access it.
  1. On the Main tab, click Global Traffic > ZoneRunner > View List. The View List screen opens.
  2. Click Create.
  3. In the View Name field, type a name for the view.
  4. From the View Order list, make a selection.
    Option Description
    First In the view hierarchy, this view is listed first.
    Last In the view hierarchy, this view is listed last.
    After In the view hierarchy, this view is listed immediately following the view that you select from the View List.
  5. In the Options area, modify the match-clients statement based on your configuration.
    View configuration type Add to match-clients statement
    Single view configuration view "external" { match-clients { "zrd-acl-000-000"; any; };
    Multiple view configuration, where you want to allow transfers from BIG-IP GTM Modify the following match-clients statement to use the IP address of the BIG-IP GTM. acl "internal-acl" { <IP address> ; }; view "internal" { match-clients { "zrd-acl-000-001"; "internal-acl"; <IP address> ; }; view "external" { match-clients { "zrd-acl-000-000"; any; };
  6. In the Options field, type additional configurations per your network design.

Types of DNS zone files

This table describes the types of DNS zone files.

DNS file type Description
Primary Zone files for a primary zone contain, at minimum, the start of authority (SOA) and nameserver (NS) resource records for the zone. Primary zones are authoritative, that is, they respond to DNS queries for the domain or sub-domain. A zone can have only one SOA record, and must have at least one NS record.
Secondary Zone files for a secondary zone are copies of the principal zone files. At an interval specified in the SOA record, secondary zones query the primary zone to check for and obtain updated zone data. A secondary zone responds authoritatively for the zone provided that the zone data is valid.
Stub Stub zones are similar to secondary zones, except that stub zones contain only the NS records for the zone. Note that stub zones are a specific feature of the BIND implementation of DNS. F5 Networks recommends that you use stub zones only if you have a specific requirement for this functionality.
Forward The zone file for a forwarding zone contains only information to forward DNS queries to another nameserver on a per-zone (or per-domain) basis.
Hint The zone file for a hint zone specifies an initial set of root nameservers for the zone. Whenever the local nameserver starts, it queries a root nameserver in the hint zone file to obtain the most recent list of root nameservers. Zone file import.

Types of DNS resource records

This table describes the types of DNS resource records that ZoneRunner supports.

DNS file type Description
SOA (Start of authority) The start of authority resource record, SOA, starts every zone file and indicates that a nameserver is the best source of information for a particular zone. The SOA record indicates that a nameserver is authoritative for a zone. There must be exactly one SOA record per zone. Unlike other resource records, you create a SOA record only when you create a new master zone file.
A (Address) The Address record, or A record, lists the IP address for a given host name. The name field is the host’s name, and the address is the network interface address. There should be one A record for each IP address of the machine.
AAAA (IPv6 Address) The IPv6 Address record, or AAAA record, lists the 128-bit IPv6 address for a given host name.
CNAME (Canonical Name) The Canonical Name resource record, CNAME, specifies an alias or nickname for the official, or canonical, host name. This record must be the only one associated with the alias name. It is usually easier to supply one A record for a given address and use CNAME records to define alias host names for that address.
DNAME (Delegation of Reverse Name) The Delegation of Reverse Name resource record, DNAME, specifies the reverse lookup of an IPv6 address. These records substitute the suffix of one domain name with another. The DNAME record instructs Global Traffic Manager (or any DNS server) to build an alias that substitutes a portion of the requested IP address with the data stored in the DNAME record.
HINFO (Host Information) The Host Information resource record, HINFO, contains information on the hardware and operating system relevant to Global Traffic Manager (or other DNS).
MX (Mail Exchanger) The Mail Exchange resource record, MX, defines the mail system(s) for a given domain.
NS (nameserver) The nameserver resource record, NS, defines the nameservers for a given domain, creating a delegation point and a subzone. The first name field specifies the zone that is served by the nameserver that is specified in the nameservers name field. Every zone needs at least one nameserver.
PTR (Pointer) A name pointer resource record, PTR, associates a host name with a given IP address. These records are used for reverse name lookups.
SRV (Service) The Service resource record, SRV, is a pointer that provides for an alias for a given service to be redirected to another domain. For example, if the fictional company SiteRequest had an FTP archive hosted on archive.siterequest.com, the IT department can create an SRV record that allows an alias, ftp.siterequest.com to be redirected to archive.siterequest.com.
TXT (Text) The Text resource record, TXT, allows you to supply any string of information, such as the location of a server or any other relevant information that you want available.

About DNSSEC

Domain Name System Security Extensions (DNSSEC) is an industry-standard protocol that functions as an extension to the Domain Name System (DNS) protocol. BIG-IP Global Traffic Manager (GTM) uses DNSSEC to guarantee the authenticity of DNS responses and to return Denial of Existence responses thus protecting your network against DNS protocol and DNS server attacks.

About DNSSEC keys

BIG-IP Global Traffic Manager (GTM) uses two types of DNSSEC keys to return DNSSEC-compliant responses: a zone-signing key to sign all of the records in a DNSSEC record set, and a key-signing key to sign only the DNSKDY record of a DNSSEC record set.

About enhancing DNSSEC key security

To enhance DNSSEC key security, BIG-IP Global Traffic Manager (GTM) uses an automatic key rollover process that uses overlapping generations of a key to ensure that BIG-IP GTM can always respond to queries with DNSSEC-compliant responses. BIG-IP GTM dynamically creates new generations of each key based on the values of the Rollover Period and Expiration Period of the key.

The first generation of a key has an ID of 0 (zero). Each time BIG-IP GTM dynamically creates a new generation of a key, the ID increments by one. Over time, each generation of a key overlaps the previous generation of the key. When a generation of a key expires, BIG-IP GTM automatically removes that generation of the key from the configuration. The value of the TTL (time-to-live) of a key specifies how long a client resolver can cache the key.

Overlapping generations of a key Overlapping generations of a key

Viewing DNSSEC records in ZoneRunner

Ensure that all DNSSEC records are added to the BIND configuration.
View the DNSSEC records using ZoneRunner.
  1. On the Main tab, click Global Traffic > ZoneRunner > Resource Record List. The Resource Record List screen opens.
  2. From the View Name list, select the name of the view that contains the resource records you want to view.
  3. From the Zone Name list, select the zone for which you want to view resource records.
  4. From the Type list, select the type of resource records you want to view.
  5. Click Search.
View the resource records that display.

Protocols supported by the BIG-IP system

This table describes the protocols supported by the BIG-IP system.

Protocol Description
iQuery protocol The gtmd agent on BIG-IP Global Traffic Manager (GTM) uses iQuery to communicate with the local big3d agent and the big3d agents installed on other BIG-IP systems.
DNS BIG-IP supports the Domain Name System (DNS) for distribution of DNS name resolution requests from clients and their local DNS servers to resources on your global network.
DNSSEC BIG-IP GTM supports the DNS Security Extensions for secure zone signing and authentication of DNS responses.
HTTPS BIG-IP supports Hypertext Transfer Protocol Secure (HTTPS) for secure web browsing.
SSL The web server, which hosts the web-based Configuration utility, supports Secure Sockets Layer (SSL) connections as well as user authentication.
SNMP BIG-IP supports the Simple Network Management Protocol (SNMP) for monitoring network resources.
SMTP BIG-IP supports the Simple Mail Transfer Protocol (SMTP) for email transmission across the Internet.
SSH BIG-IP supports Secure Shell (SSH) administrative connections for remote administration from the command line.
TCP wrappers BIG-IP supports the use of TCP wrappers to provide an extra layer of security for network connections.
FTP BIG-IP supports the File Transfer Protocol (FTP) for secure access to BIG-IP system software downloads from a web server.
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