Management Central connection considerations

Understanding how Management Central establishes a connection is an important contributing factor toward a successful installation and setup. Whether your system configuration is complex or simple there are many considerations that affect a successful connection.

How Management Central establishes a connection

When the Management Central Java™ server (QYPSJSVR) starts it obtains the IP address for itself, by long name (system + domain name), from TCP/IP. Typically, the clients that appear under My Connections and the Management Central endpoints are defined by the system name or short name.

The iSeries™ Navigator lookup frequency default is Always. This setting causes a system that is listed under My Connections to use the DNS or the TCP/IP host table (Configure TCP/IP (CFGTCP) option 10) to determine the IP address so that it can connect to the central system. The Host Name Search Priority (Configure TCP/IP (CFGTCP) option 12) option controls how the DNS search is done. If it is *LOCAL, it will search the TCP/IP host table first. If it does not find it there, it will use the DNS. If it is *REMOTE, then the DNS is searched first, followed by the TCP/IP host table.

Connection timeout delay

When the Management Central servers on an endpoint are not running, a connection failure happens right away. However, if the system is down or if a bad IP address is being used, the connection cannot be made and there will be a several minute timeout delay before the connection failure is posted.

Connection tests

Management Central uses the IP address of the system located under My Connection to connect to the Central System. When Management Central performs a connection test it does a ping on the PC of the name that is being used for the Central System (typically short name) and then it returns the same IP address as a Ping on the Central System by the long name. If this is not successful, then the client cannot connect with the Java server. You can resolve this by overriding the Central System's IP address.

To override the IP address on the Central System use the following character-based command:

CALL PGM(QSYS/QYPSCONFIG) PARM(xxxx 'y.y.y.y') 
Where xxxx is the setting QYPSHOSTNAME and y.y.y.y is the value of the IP address to be used.

Important: Edit the file using the character-based interface. Do not use a mapped drive, or other method.

Lookup frequency

The system environment variable QYPS_DNS sets the Management Central lookup frequency (values 0 = Never, 1 = Always). You can set the QYPS_DNS system variable by using one of these methods:

Management Central properties window
The Connection tab on the client
Use the character-based interface to add an environment variable
```
CALL PGM(QSYS/QYPSCONFIG) PARM(xxxx 'y') 
```
Where QYPS_DNS is the setting and y is the value 0 or 1.

It is recommended that the lookup frequency is set to Always. When the lookup frequency is set to Always, the IP address in the properties of the endpoint is ignored and a request for the IP address via the DNS or the Host Table on the central system is made. As a result, if IP addresses are changed or if the DNS or host table is changed, the new IP address is automatically picked up by Management Central.

When the lookup frequency is set to Never, the IP address that is contained in the properties of the endpoint object is used. As a result, it is possible that a client can successfully connect to the central system which uses the IP address that is determined by the My-Connection, but then have a task run to the central system and have a connection failure. Such an event indicates that the Management Central lookup frequency is set to Never and that the IP address in the endpoint for the central system is incorrect. To resolve this situation, edit the IP address for the endpoint on the endpoint properties window.

Note: The Management Central lookup frequency is a different setting than the lookup frequency setting for a system under My Connections.

Connecting to a Java server

When a client connects to a Java server, the Java server uses an authentication procedure that connects back to the PC. Therefore, the central server must be able to ping the PC.

A common connection problem occurs when the PC's address is one that is reserved for private networks (such as when an individual uses VPN from home to gain access to their network behind their router). For example, assume the PC's address is 10.100.46.143 and the IP address of the central system is 164.143.28.82. A connection failure occurs because addresses that start with 10 are not forwarded by routers. In such a situation, you need to find out what the external IP address of the PC is and then set up a client C:\MgmtCtrl.properties file, and then add the line QYPS_HOSTNAME=xxx.xxx.xxx.xxx (where the xxx's are the external IP address of the PC). This causes the Java server use the IP address specified in the properties file to connect to the PC.

Management Central bulk data transfer considerations

A bulk transfer is a function that is used in Management Central to transfer data from a source system to a target system (such sending of a package, sending PTFs, and so on). For a successful transfer, the target system needs to be able to connect back to the source system. The IP address that is used on the target system is determined by the lookup frequency on the target system. If the lookup frequency is Never then the IP address that is used is the one that is provided by the central system for the source system. If the lookup frequency on the target system is set to Always then it will use DNS or the host table to determine the IP address of the source system.

Running Management Central tasks from My Connections

Some of the iSeries Navigator functions use Management Central to obtain information. For example, you can view PTFs that are in Inventory by using My Connections > Configuration and Service. If Management Central cannot connect to the central system then the function that you are trying to access will experience a several minute time out delay. This results in a connection failure message. A good practice to follow is to expand Management Central before you attempt to run any Management Central functions that are located under My Connections. By doing so, you will make sure that you can connect to the central system.

To run a Management Central task on a system in My Connections, the system must also be defined as an endpoint under Management Central. To define a system as an endpoint expand Management Central > Right-click Endpoint Systems > New Endpoint Systems.