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Archived Manual Chapter: 3-DNS Administrator Guide version 4.2: Essential Configuration Tasks
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6

Essential Configuration Tasks



Reviewing the configuration tasks

Once you have completed the Setup utility, you set up the network and load balancing aspects of the 3-DNS. The 3-DNS has three essential configuration tasks that all users must complete, regardless of the chosen load balancing solution.

The 3-DNS has three essential configuration tasks that must be completed, regardless of the type of configuration you are setting up:

  • Configure the physical aspects of your load balancing network, which includes the following:
    • Data centers
    • Data center servers and their virtual servers
    • Communications between the 3-DNS and other servers
    • 3-DNS synchronization (if you have more than one 3-DNS in your network)
  • Configure the logical aspects of your load balancing network, including wide IPs and pools
  • Configure the global load balancing modes and global variables

Setting up a basic configuration

Each 3-DNS in the network setup must have information regarding which data center houses specific servers, and with which other 3-DNS systems it can share configuration and load balancing information. A basic network setup includes data centers, servers, and one sync group. Once you have the basic network components configured on your 3-DNS, you can set up the wide IPs you need for managing your load balancing. We recommend that you review the load balancing solutions in the remaining chapters of this guide before you configure the wide IPs.

The following sections describe the various elements of a basic network:

  • Data centers
    Data centers are the top level of your network setup. We recommend that you configure one data center for each physical location in your global network. The data center element of your configuration defines the servers (3-DNS systems, BIG-IP systems, EDGE-FX Caches, and hosts) that reside at that location.

    A data center can contain any type of server. For example, in Figure 6.1 on page 6-3 , the Tokyo data center contains a 3-DNS and a host, while the New York and Los Angeles data centers contain 3-DNS systems and BIG-IP systems.

    For information about configuring data centers, see Setting up a data center, on page 6-2 .
  • Servers
    The data center servers that you define in the network setup include 3-DNS systems, BIG-IP systems, GLOBAL-SITE systems, EDGE-FX Caches, and host machines. You define the 3-DNS systems that manage load balancing to the BIG-IP systems, EDGE-FX Caches, and hosts, and you also define the virtual servers that are managed by the servers. Virtual servers are the ultimate destination for connection requests.

    For information about configuring servers, see Setting up servers, on page 6-5 .
  • Sync groups
    Sync groups contain only 3-DNS systems. When setting up a sync group, you define which 3-DNS systems have the same configuration. In most cases, you should define all 3-DNS systems as part of the same sync group.

    For information about configuring sync groups, see Working with sync groups, on page 6-19 .
  • Wide IPs
    After you define virtual servers for your BIG-IP systems, EDGE-FX Caches, and hosts, you need to define wide IPs to specify how connections are distributed among the virtual servers. A wide IP maps a domain name to a pool of virtual servers, and it specifies the load balancing modes that the 3-DNS uses to choose a virtual server from the pool.

    When a local DNS server requests a connection to a specific domain name, the wide IP definition specifies which virtual servers are eligible to answer the request, and which load balancing modes to use in choosing a virtual server to resolve the request.

    For information about configuring wide IPs and choosing load balancing modes, please refer to Chapter 8, Load Balancing, in the 3-DNS Reference Guide.
  • Global variables
    You can configure global variables that apply to all servers and wide IPs in your network. However, the default values of the global variables work well for most situations, so configuring global variables is optional.

For information about configuring global variables, see Configuring global variables, on page 6-22 .

Setting up a data center

The first step in configuring your 3-DNS network is to create data centers. A data center defines the group of 3-DNS, BIG-IP, GLOBAL-SITE, EDGE-FX Cache, and host systems that reside in a single physical location. Figure 6.1 on page 6-3 shows an example of a data center.

The advantage of grouping all machines from a single physical location into one data center in the configuration is to allow path information collected by one server to be shared with all other servers in the data center. The 3-DNS uses the big3d agent to collect path and metrics information about the other servers, and their virtual servers, in the data center. The 3-DNS then applies path metrics results to all the virtual servers in the data center when making load balancing decisions.

Note: You must configure at least one data center before you can add servers to the 3-DNS configuration.

Figure 6.1 Example data center setup

When you add servers to the network setup, you assign the servers to the appropriate data centers.

To configure a data center using the Configuration utility

  1. In the navigation pane, click Data Centers.
  2. On the toolbar, click Add Data Center.
    The Add New Data Center screen opens.
  3. Add the new data center settings. For help on defining data centers, click Help on the toolbar.
    The data center is added to your configuration.
  4. Repeat this process for each data center in your network.

To configure a data center from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. Select Edit 3-DNS Configuration to open the wideip.conf file.
    The EDITOR environment variable determines whether this command starts vi or pico.
  3. Locate or add the datacenter statement.

    The datacenter statement should be the second statement in the file, after the globals statement and before server statements.

  4. In the first line of the datacenter statement, type a name for the data center and enclose the name in quotation marks, as shown in Figure 6.2 .
  5. Type the server type and IP address for each server that is part of the specified data center.

Figure 6.2 shows the correct syntax for the datacenter statement.

Figure 6.2 Syntax for the datacenter statement

 datacenter {    
name <"data center name">
[ location <"location info"> ]
[ contact <"contact info"> ]
[ 3dns <IP address> ]
[ bigip <IP address> ]
[ edge_fx <IP address> ]
[ gsite <IP address> ]
[ host <IP address> ]
}

Repeat the preceding procedure until you have added a separate datacenter statement for each data center in your network.

Figure 6.3 shows a sample datacenter statement.

Figure 6.3 Sample data center definition

 datacenter {    
name "New York"
location "NYC"
contact "3DNS_Admin"
3dns 192.168.101.2
bigip 192.168.101.40
host 192.168.105.40
}

Setting up servers

There are five types of servers you can configure on a 3-DNS: 3-DNS, BIG-IP, GLOBAL-SITE, EDGE-FX Cache, and host. At the minimum, your network includes one 3-DNS, and at least one server (BIG-IP, EDGE-FX Cache, GLOBAL-SITE, or host) that it manages.

This section describes how to set up each server type--3-DNS, BIG-IP, EDGE-FX Cache, GLOBAL-SITE, and host--that makes up your network. The setup procedures here assume that the 3-DNS, BIG-IP, EDGE-FX Cache, GLOBAL-SITE, and host systems are up and running, and that they already have virtual servers defined. (Note that 3-DNS and GLOBAL-SITE systems do not manage virtual servers.)

Defining 3-DNS systems in the configuration

The purpose of defining a 3-DNS in the configuration is to establish in which data center the 3-DNS resides and, if necessary, to change big3d agent settings. Before you add other 3-DNS systems to the configuration, you should add the 3-DNS you are configuring to its own configuration. By adding any additional 3-DNS systems to the configuration, you make those 3-DNS systems available so that you can add them to a sync group.

Note: Please review Chapter 11, Adding a 3-DNS to an Existing Network , if you are configuring more than one 3-DNS in your network.

To define a 3-DNS using the Configuration utility

  1. In the navigation pane, expand the Servers item, then click 3-DNS.
  2. On the toolbar, click Add 3-DNS.
    The Add New 3-DNS screen opens.
  3. Add the new 3-DNS settings. For help on defining 3-DNS systems, click Help on the toolbar.

The 3-DNS is added to your configuration.

Repeat this procedure for each 3-DNS you need to add.

To define a 3-DNS from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Use the syntax shown in Figure 6.4 to define a 3-DNS.

    All server statements should appear after the sync_group statement and before wideip statements.

    Figure 6.4 Syntax for defining a 3-DNS

     server {    
    type 3dns
    address <IP address>
    name <"3dns_name">
    iquery_protocol [ udp | tcp ]
    [ remote {
    secure <yes | no>
    user <"user name">
    } ]
    [ interface {
    address <NIC IP address>
    address <NIC IP address>
    } ]
    [ factories {
    prober <number>
    snmp <number>
    hops <number>
    ecv <number>
    } ]
    }

    Figure 6.5 shows a sample server statement that defines a 3-DNS.

    Figure 6.5 Sample 3-DNS definition

     // New York    
    server {
    type 3dns
    address 192.168.101.2
    name "3dns-newyork"
    iquery_protocol udp
    remote {
    secure yes
    user "root"
    }
    }

Defining BIG-IP systems

Before you define BIG-IP systems in the configuration, you should have the following information:

  • The IP address and service name or port number of each virtual server to be managed by the BIG-IP
  • The IP address of the BIG-IP itself

To define a BIG-IP using the Configuration utility

  1. In the navigation pane, expand the Servers item, and then click BIG-IP.
  2. On the toolbar, click Add BIG-IP .
    The Add New BIG-IP screen opens.
  3. Add the new BIG-IP settings. (For help on defining BIG-IP systems, click Help on the toolbar.)
    The BIG-IP and specified virtual server are added to your configuration.

To add more virtual servers using the Configuration utility

  1. In the navigation pane, expand the Servers item, and then click BIG-IP.
  2. In the table, find the BIG-IP that you just added.
  3. Click the entry in its BIG-IP Virtual Servers column.
  4. On the toolbar, click Add Virtual Server.
    The Add Virtual Server to BIG-IP screen opens.
  5. Add the new virtual server settings. For help on adding virtual servers, click Help on the toolbar.

Repeat this process for each virtual server you want to add to this BIG-IP.

To define a BIG-IP from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Use the syntax shown in Figure 6.6 to define a BIG-IP.

All server statements should appear after the sync_group statement and before wideip statements.

If you need to allow iQuery packets to pass through firewalls, include the translate keyword in the server statement that defines the BIG-IP. When you include the translate keyword, the iQuery utility includes translated IP addresses in the packets sent to the specific BIG-IP. For more information on configuring the big3d agent and iQuery, see Chapter 4, The big3d Agent, of the 3-DNS Reference Guide.

Figure 6.6 Syntax for defining a BIG-IP in the wideip.conf file

 server {    
type bigip
address <IP address>
name <"bigip_name">
iquery_protocol [ udp | tcp ]
[ limit {
[ kbytes_per_second <number>
packets_per_second <number>
disk_avail <number>
cpu_usage <number>
memory_avail <number>
current_connections <number> ]
} ]
[ remote {
secure <yes | no>
user <"user name">
} ]
[ interface {
address <NIC IP address>
address <NIC IP address>
} ]
[ factories {
prober <number>
snmp <number>
hops <number>
ecv <number>
} ]

vs {
address <virtual server IP address>
port <port number> | service <"service name">
[ depends_on {
address <IP address>
address <IP address>
} ]
[ translate {
address <IP address>
port <port number>|service <"service name">
} ]
}
}

Figure 6.7 shows a sample server statement that defines a BIG-IP.

Figure 6.7 Sample BIG-IP definition

 server {     
type bigip
address 192.168.101.40
name "bigip-newyork"
iquery_protocol udp
remote {
secure yes
user "administrator"
}
# Tell 3-DNS about the 2 interfaces on a BIG-IP HA
interface {
address 192.168.101.41
address 192.168.101.42
}
# Change the number of factories doing the work at big3d
factories {
prober 6
discovery 1
snmp 1
hops 2
}
vs {
address 192.168.101.50
service "http"
translate {
address 10.0.0.50
port 80
}
}
vs {
address 192.168.101.50:25 // smtp
translate {
address 10.0.0.50:25
}
}
}

Defining a BIG-IP with the 3-DNS module in the configuration

In the 3-DNS configuration, you treat the BIG-IP platform and the 3-DNS module as if they were separate devices. You can add the two server types either by using the Configuration utility or by editing the wideip.conf file. The following instructions describe how to add a BIG-IP with the 3-DNS module, with the name combo.domain.net and the IP address 192.168.100.100, to the configuration.

Before you define a BIG-IP with the 3-DNS module in the 3-DNS configuration, you should have the following information:

  • The name and IP address of the BIG-IP
  • The name and IP address of the 3-DNS

To add a BIG-IP with the 3-DNS module using the Configuration utility

  1. In the navigation pane, expand the Servers item, and then click BIG-IP.
    The BIG-IP List screen opens.
  2. On the toolbar, click Add BIG-IP.
    The Add BIG-IP screen opens.
  3. In the BIG-IP Name box, type combo.domain.net.
  4. In the BIG-IP IP Address box, type 192.168.100.100.
  5. Add the rest of the settings as needed.

    When you have finished defining the BIG-IP, you can add the 3-DNS module to the configuration.

  6. In the navigation pane, expand the Servers item, and then click 3-DNS.
    The 3-DNS List screen opens.
  7. On the toolbar, click Add 3-DNS.
    The Add 3-DNS screen opens.
  8. In the 3-DNS Name box, type combo.domain.net.
  9. In the 3-DNS IP Address box, type 192.168.100.100.
  10. Add the rest of the settings as needed.

Note that both server types use the same name and IP address, as shown in Figure 6.8 . If you are configuring a redundant system, you use the shared IP address. For assistance, contact technical support.

To add a BIG-IP with the 3-DNS module from the command line

  1. At the command line, type 3dnsmaint.
    The 3-DNS Maintenance menu opens.
  2. Using the arrow keys, choose Edit 3-DNS Configuration.
  3. Add the server definitions for both the BIG-IP and the 3-DNS to the wideip.conf file. Use the syntax in Figure 6.8 as an example.

    Figure 6.8 Sample definition of a BIG-IP with the 3-DNS module

     server { // datacenter=DC1, #VS=1
    type bigip

    address 192.168.100.68
    name "birch.win.net"
    limit { /* none */ }
    iquery_protocol udp
    remote {
    secure yes
    user "root"
    }
    factories {
    snmp 1
    }
    prober 127.0.0.1
    }

    server { // datacenter=DC1, #VS=0
    type 3dns
    address 192.168.100.68
    name "birch.win.net"
    limit { /* none */ }
    iquery_protocol udp
    remote {
    secure yes
    user "root"
    }
    factories {
    snmp 1
    }
    }

Defining a GLOBAL-SITE in the configuration

The 3-DNS uses the GLOBAL-SITE for path probing and metrics collection only. The GLOBAL-SITE does not manage any virtual servers. Before you define a GLOBAL-SITE in the 3-DNS configuration, you should have the following information:

  • The name of the GLOBAL-SITE
  • The IP address of the GLOBAL-SITE

To define a GLOBAL-SITE using the Configuration utility

  1. In the navigation pane, expand the Servers item, then click GLOBAL-SITE.
  2. On the toolbar, click Add GLOBAL-SITE.
    The Add New GLOBAL-SITE screen opens.
  3. Add the new GLOBAL-SITE settings. For help on defining a GLOBAL-SITE, click Help on the toolbar.
    The GLOBAL-SITE is added to your configuration.

To define a GLOBAL-SITE from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Use the syntax shown in Figure 6.9 to define a GLOBAL-SITE.

Figure 6.9 Syntax for defining a GLOBAL-SITE

 server {    
type gsite
address <IP address>
name <"gsite_name">
iquery_protocol [ udp | tcp ]
[ remote {
secure <yes | no>
user <"user name">
}]
[ factories {
prober <number>
snmp <number>
hops <number>
ecv <number>
}]
}

In the wideip.conf file, all server statements should appear after the sync_group statement and before wideip statements.

Figure 6.10 shows a sample server statement that defines a GLOBAL-SITE.

Figure 6.10 Sample GLOBAL-SITE definition

 server { // datacenter=East Coast    
type gsite
address 192.168.10.150
name "gsite_east1
iquery_protocol udp
remote { secure yes
user "root" }
factories {
hops 1 }
}
}

Defining EDGE-FX Caches

Before you define EDGE-FX Cache servers, you should have the following information:

  • The IP address and service name or port number of each virtual server to be managed by the EDGE-FX Cache
  • The IP address of the cache itself

To define an EDGE-FX Cache server using the Configuration utility

  1. In the navigation pane, expand the Servers item, then click EDGE-FX Caches.
  2. On the toolbar, click Add EDGE-FX Cache.
    The Add New EDGE-FX Cache screen opens.
  3. Add the new EDGE-FX Cache settings. For help on defining an EDGE-FX Cache, click Help on the toolbar.
    The EDGE-FX Cache and specified virtual server are added to your configuration.

To add more virtual servers using the Configuration utility

  1. In the navigation pane, click Servers, then click EDGE-FX Caches.
  2. In the table, find the EDGE-FX Cache that you just added.
  3. Click the entry in its EDGE-FX Virtual Servers column.
  4. On the toolbar, click Add Virtual Server.
    The Add Virtual Server to EDGE-FX screen opens.
  5. Add the new virtual server settings. For help on adding virtual servers, click Help on the toolbar.

Repeat this process for each virtual server you want to add to this EDGE-FX Cache.

To define an EDGE-FX Cache server from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Use the syntax shown in Figure 6.11 to define an EDGE-FX Cache.

Figure 6.11 Syntax for defining an EDGE-FX Cache

 server {    
type edge_fx
address <IP address>
name <"edge_name">
iquery_protocol [ udp | tcp ]
[ limit {
[ kbytes_per_sec <number>
pkts_per_sec <number>
current_conns <number>
cpu_usage <number>
mem_avail <number>
disk_avail <number> ]
} ]
[ remote {
secure <yes | no>
user <"user name">
}]
[ factories {
prober <number>
snmp <number> //minimum of 1 to collect metrics
hops <number>
ecv <number>
}]
vs {
address <virtual server IP address>
port <port number> | service <"service name">
[ depends_on {
address <IP address>
address <IP address>
} ]
}
}

In the wideip.conf file, all server statements should appear after the sync_group statement and before wideip statements.

If you need to allow iQuery packets to pass through firewalls, include the translate keyword in the server statement that defines the EDGE-FX Cache. When you include the translate keyword, the iQuery utility includes translated IP addresses in the packets sent to the specific EDGE-FX Cache. For more information on configuring the big3d agent and iQuery, see Chapter 4, The big3d Agent, of the 3-DNS Reference Guide.

Figure 6.12 shows a sample server statement that defines an EDGE-FX Cache.

Figure 6.12 Sample EDGE-FX Cache server definition

 server { // datacenter=East Coast, #VS=1    
type edge_fx
address 192.168.10.150
name "edge_east1"
limit { /* none */ }
iquery_protocol udp
remote { secure yes
user "root"
}
factories {
snmp 1
}
vs {
address 10.10.10.10:80 // http
limit { /* none */ }
probe_protocol tcp
}
}

Defining host servers

A host is an individual network server or server array controller other than a 3-DNS, BIG-IP, EDGE-FX Cache, or GLOBAL-SITE. Before configuring a host, you should have the following information:

  • Address information
    The IP address and service name or port number of each virtual server to be managed by the host.
  • SNMP information for host probing
    To implement host probing and to collect performance metrics, you must specify SNMP agent settings after you define the host server. The settings you specify include the type and version of SNMP agent that runs on the host, the community string, and the number of communication attempts that you want the big3d agent to make while gathering host metrics. SNMP agent settings for hosts are described in Configuring host SNMP settings, on page 6-18 .

Note: To fully configure host probing, you must configure the SNMP agent settings in the host definition as previously described, set up the big3d agents to run SNMP factories, and configure the SNMP agents on the hosts themselves. For details, please refer to Chapter 4, The big3d Agent, and Chapter 12, SNMP, in the 3-DNS Reference Guide.

To define a host using the Configuration utility

  1. In the navigation pane, expand the Servers item, and then click Host.
  2. On the toolbar, click Add Host.
    The Add New Host screen opens
  3. Add the new host server settings. For help on adding host servers, click Help on the toolbar.
    The host and the specified virtual server are added to your configuration.

    To add more virtual servers using the Configuration utility

  4. In the navigation pane, click Host.
  5. In the table, find the host that you just added, and click the entry in its Host Virtual Servers column.
  6. On the toolbar, click Add Host Virtual Server.
    The Add Virtual Server to Host screen opens.
  7. Add the new virtual server settings. For help on adding virtual servers, click Help on the toolbar.

    Repeat this process for each virtual server you want to add to this host.

To define a host server from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Use the syntax shown in Figure 6.13 to define a host.

All server statements should appear after the sync_group statement and before wideip statements.

Figure 6.13 Syntax for defining a host

 server {    
type host
address <IP address>
name <"host_name">
[ prober <ip_address> ]
probe_protocol <tcp | icmp | dns_rev | dns_dot>
port <port number> | service <"service name">
[ snmp {
agent <generic | ucd | solstice | ntserv | ciscoldv2 | ciscoldv3
| arrowpoint | foundry | alteon | cacheflow | win2kserv>

port <port number>
community <"community string">
timeout <seconds>
retries <number>
version <SNMP version>
} ]
vs {
address <virtual server IP address>
port <port number> | service <"service name">
[ depends_on {
address <IP address>
address <IP address>
} ]
[ probe_protocol <tcp | icmp | dns_rev | dns_dot> ]
}
}

Figure 6.14 shows a sample server statement that defines a host.

Figure 6.14 Sample host definition

 server {     
type host
address 192.168.104.40
name "host-tokyo"
prober 192.168.101.40
probe_protocol dns_rev
port 53
snmp {
agent ucd
community "public"
version 1
}
vs {
address 192.168.104.50:25
}
vs {
address 192.168.104.50:80
}
}

Configuring host SNMP settings

After defining a host server, you need to configure its SNMP settings if you want to use SNMP host probing. Remember that you must first set up at least one SNMP probing factory on any 3-DNS, BIG-IP, EDGE-FX Cache, or GLOBAL-SITE that runs the big3d agent and is in the same data center as the host.

The SNMP prober collects some or all of the following information from hosts.

  • Memory utilization
  • CPU utilization
  • Disk space utilization
  • Packet rate (packets per second
  • Throughput rate (kilobytes per second)
  • Current connections

The 3-DNS uses this performance information for dynamic load balancing modes, such as Packet Rate, Quality of Service, and Kilobytes/Second.

Table 6.1 shows the host SNMP agents supported by the 3-DNS.

Supported SNMP agents

SNMP Agent

Description

Generic

A generic SNMP agent is an SNMP agent that collects metrics provided by object identifiers (OIDs) as specified in the RFC 1213 document.

UCD

This free SNMP agent is provided by the University of California at Davis. It is available on the web at http://net-snmp.sourceforge.net

Solstice

This SNMP agent is a product of Sun® Microsystems.

NTServ

This SNMP matrix agent is distributed with Microsoft® Windows NT® Server 4.0.

Win2KServ

This SNMP matrix agent is distributed with Microsoft Windows 2000 Server.

Cisco LDV2

This SNMP agent is distributed with the Cisco® LocalDirector, version 2.X.

Cisco LDV3

This SNMP agent is distributed with the Cisco LocalDirector, version 3.X.

ArrowPoint

This SNMP agent is distributed with the Cisco/ArrowPoint CSS series.

Alteon

This SNMP agent is distributed with the Alteon® WebSystems ACEdirector.

Foundry

This SNMP agent is distributed with the Foundry® ServerIron.

CacheFlow

This SNMP agent is distributed with the CacheFlow® appliances.

Viewing host performance metrics

The Configuration utility displays the host metrics in the Host Statistics screen. The 3-DNS bases the advanced load balancing decisions on packet rate, kilobytes per second, and current connections metrics, but the Host Statistics screen displays the other metrics as well, for information purposes.

Reviewing SNMP configuration issues

The SNMP probing feature requires that each host run an SNMP agent, and that the hosts and the big3d agents in the data centers have open network communication. Certain firewall configurations block SNMP communications, and you may need to verify that the firewalls in your network allow SNMP traffic to pass through. For information on configuring the big3d agent and working with firewalls, see Chapter 4, The big3d Agent, in the 3-DNS Reference Guide.

In addition to properly configuring the SNMP agents on the hosts themselves, you need to specify SNMP host probing settings in two places in the 3-DNS configuration. First, when you define a 3-DNS or BIG-IP, you set the big3d agent to run at least one SNMP factory. Second, when you define the host servers, you configure specific SNMP agent settings for each host. For example, you need to specify the type of agent running on the host as well as the community string that allows access to the SNMP agent. For more information on configuring SNMP agents, review Chapter 12, SNMP, in the 3-DNS Reference Guide.

The SNMP chapter also includes some useful tips on configuring the different SNMP agents on the hosts themselves. We recommend that you use the information in conjunction with the documentation originally provided with the SNMP agent.

Working with sync groups

A sync group defines a group of 3-DNS systems that synchronize their configuration settings and metrics data. A sync group contains a principal system and one or more receiver systems. The principal system is the 3-DNS from which the receiver systems obtain their metrics and server statistics information. You configure a sync group from the principal 3-DNS. First list the IP address of the principal itself. Then list the receiver 3-DNS systems in the order that they should become principals if previously listed 3-DNS systems fail.

Each 3-DNS in your network must be included in a sync group. There may be cases where you do not want a 3-DNS to share its configuration with other systems. In this case, you can create a separate sync group for each 3-DNS. Each sync group contains only its own name or IP address

Figure 6.15 Sample non-syncing sync groups statements

 sync_group {    
name "sync-ny"
3dns 192.168.101.2 // New York
}

sync_group {
name "sync-la"
3dns 192.168.102.2 // Los Angeles
}

Note: To implement such a configuration, you must modify each 3-DNS system's wideip.conf file; the Configuration utility does not support this function.

Configuring sync groups

The following procedures describe how to configure sync groups.

To define a sync group using the Configuration utility

  1. In the navigation pane, click 3-DNS Sync.
    The System - Add a New Sync Group screen opens.
  2. In the New Sync Group Name box, type the name of the new sync group and click Add.
    The Add a 3-DNS to a Sync Group screen opens.
  3. From the list of 3-DNS systems, first select the 3-DNS that you want to be the principal system. Then check the box next to each 3-DNS that you want to add to the sync group.
  4. Click Add.

To define a sync group from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Use the syntax shown in Figure 6.16 to define sync groups.

    The sync_group statement should appear after the datacenter statement and before server statements.

    Figure 6.16 Syntax for setting up a sync group

     sync_group {    
    name "<name>"
    3dns <ip_address | "domain_name">
    [ 3dns <ip_address | "domain_name"> ] ...
    }

    Figure 6.17 shows a sample sync_group statement.

    Figure 6.17 Sample sync group definition

     sync_group {    
    name "default"
    3dns 192.168.101.2 // New York
    3dns 192.168.102.2 // Los Angeles
    }

Setting the time tolerance value

The time tolerance value is a global variable that defines the number of seconds that one 3-DNS system's time setting is allowed to be out of sync with another 3-DNS system's time setting. We recommend that you leave the time tolerance variable at the default setting of 10.

To check the value for the time tolerance setting using the Configuration utility

  1. In the navigation pane, click System.
    The System - General screen opens.
  2. On the toolbar, click Timers and Task Intervals.
  3. Note the value in the 3-DNS Sync Time Tolerance box, and change it if necessary.
  4. If you change this setting, click Update to save it. For more information about the settings on this screen, click Help on the toolbar.

To check the value for the time tolerance setting in the configuration file

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, select Edit 3-DNS Configuration to open the wideip.conf file.
  3. Search for time_tolerance. If the time_tolerance sub-statement is not in the configuration file, the default (10) is used.

Configuring global variables

The default values for global parameters are sufficient for most load balancing situations. However, we recommend that you specifically enable encryption for crypto 3-DNS systems.

To configure global parameters using the Configuration utility

  1. In the navigation pane, click System.
    The System - General screen opens. Note that global parameters are grouped into several categories on this screen. Each category has its own toolbar item, and online help is available for each parameter.
  2. Make general global changes at the System - General screen or, to make changes to global parameters in other categories, click the appropriate toolbar item.
  3. Add the new global settings. For help on configuring the global settings, click Help on the toolbar.

    The new global parameters are added to your configuration.

To configure global parameters from the command line

  1. At the command prompt, type 3dnsmaint to open the 3-DNS Maintenance menu.
  2. On the 3-DNS Maintenance menu, choose Edit 3-DNS Configuration to open the wideip.conf file.
  3. Locate or add the globals statement. The globals statement should be at the top of the file.
  4. Under the globals statement, type the appropriate sub-statement and value.

For example, to enable encryption for iQuery transactions (which is recommended), change the encryption parameter to yes (the default setting is no). If you want to use a non-default name for the encryption key file, type it on the next line.

Figure 6.18 shows the correct syntax for enabling encryption.

Figure 6.18 Syntax for enabling encryption

 globals {    
encryption yes
encryption_key_file "/etc/F5key.dat"
}
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