11.1 Understanding Closest Servers

ZENworks provides a means for allowing agents to communicate with different servers, at different locations, for different information. In a default installation, all of the agents will communicate only with the Primary Servers and will default to communicating with the first server installed, then the next, and so on until such time as no server is available to respond. To ensure performance and fault tolerance, it is important to properly configure your closest servers so that the traffic flows appropriately based on your network topology.

Closest servers can be configured in the following places within ZENworks:

  • Network Location: A network location is a logical grouping of one or more network environments, for instance a location called Office might represent any of your offices around the world. A location called Provo might represent all of the networks in your Provo office. There is also a special location called Unknown which indicates that you are in a location not defined by the administrator. The unknown location is often used to control which servers should be used for devices connecting via the network.

  • Network Environment: A network environment represents a unique logical network of devices. It can consist of several conditions that define the network, including DNS server, Gateway, IP address, ESSID, WINS server, and more. Networks are typically created to represent each site managed by ZENworks, and are often used for defining the closest servers.

  • Default Closest Servers: If a location or network environment set of closest servers is not configured, or if they are configured to include the default closest servers, the default closest servers are used. Default closest servers include all the existing Primary Servers in the zone.

The closest server list is an ordered list, which means that the managed devices will always attempt to contact the first server in the list, and then the next, until it runs out of servers that have been configured for it. This means that in the default configuration, all your agents will attempt to communicate with the first server in the zone, even if you have multiple, other servers. Therefore, it is critical that you configure the closest server rules. Additionally, you might want to configure Closest Server Groups or use an L4 switch as discussed in Load Balancing Between Primary and Satellites.

Within each closest server rules list there are multiple role-based server rules that can be defined. This enables you to control the functions that a server provides to a set of clients. For instance, you might want to use a server as a dedicated ZENworks Control Center server and a packaging source for content. In this case you would want to ensure that no managed devices reference this server; rather, only the Content Satellites that need to get the packaged content from the server. The following roles are available to define closest servers:

  • Content: This role is used by the agent to determine the server(s) from which it should request content (from the content repository). When an agent makes a request for content, it asks the servers that have that content as a source and that exist in its effective content servers list. ZENworks Satellites can be configured to replicate content in the same fashion, allowing Satellites to pull content from other Satellites when replicating where appropriate.

  • Authentication: This role is used to determine the server that will perform LDAP authentication operations on behalf of the managed device. This should be configured to point to a server close to the Active Directory Server or eDirectory replica server on which you want to perform the LDAP authentication. All managed devices will attempt to connect to a Configuration Server after authenticating to LDAP to obtain configuration data.

  • Configuration: This role is used to read and write data from the ZENworks database. This role is only provided by Primary Servers. It is required that all Primary Servers and the database be located on a low latency, 10 Mbp/s connection with each other, preferably on a 1 Gbp/s network.

  • Collection: This role is used to send most data from the managed agent to the server, including audit events, status information, messages, effective policy data, patch scan results, and more. If you have more than a few workstations on a site, it is recommended that you have a Collection Satellite that will collect the data, aggregate and compress it, and then roll-it up to its Parent Primary Server.

  • Join Proxy: This role is used to provide remote management capabilities for devices that are on the Internet. Generally, you will only configure join proxy servers on locations that are known to be, or highly likely to be, behind a NAT.

Closest server configuration is crucial to a properly functioning ZENworks system and to ensure that the impact on your overall network is minimized.