VM Connectivity Test

Sometimes, a VM could be in a powered-on state, but the failure of the VM operating system or any fatal error in VM operations could have rendered the VM inaccessible to users. In order to enable administrators to promptly detect such ‘hidden’ anomalies, the eG agent periodically runs a connectivity check on each VM using the VM Connectivity test, and reports whether the VM is accessible over the network or not.

Target of the test : A Citrix Hypervisor host

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each VM configured on the target hypervisor host being monitored

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed.

Host

The host for which the test is to be configured.

Port

The port at which the specified host listens. By default, this is NULL.

Xen User, Xen Password and Confirm Password

To enable the eG agent to connect to the XenServer API for collecting statistics of interest, this test should login to the target hypervisor as a root user. Provide the name of the root user in the Xen User text box. Root user privileges are mandatory when monitoring a XenServer 5.5 (or below). However, if you are monitoring XenServer 5.6 (or above) and you prefer not to expose the credentials of the root user, then, you have the option of configuring a user with pool-admin privileges as the Xen User. If you do not want to expose the credentials of a root/pool-admin user, then you can configure the tests with the credentials of a Xen User with Read-only privileges to the XenServer. However, if this is done, then the Xen Uptime test will not run, and the Xen CPU and Xen Memory tests will not be able to report metrics for the control domain descriptor. To avoid such an outcome, do the following before attempting to configure the eG tests with a Xen User who has Read-only privileges to the Citrix Hypervisor:

  • Modify the target hypervisor's configuration in the eG Enterprise. For this, follow the Infrastructure -> Components -> Add/Modify menu sequence, pick Citrix Hypervisor as the Component type, and click the Modify button corresponding to the target hypervisor.
  • In the MODIFY COMPONENT DETAILS page that then appears, make sure that the os is set to Xen and the Mode is set to SSH.
  • Then, in the same page, proceed to provide the User and Password of a user who has the right to connect to the XenServer console via SSH.
  • Then, click the Update button to save the changes.

Once this is done, you can configure the eG tests with the credentials of a Xen User with Read-only privileges.

The password of the specified Xen User needs to be mentioned in the Xen Password text box.

Then, confirm the Xen Password by retyping it in the Confirm Password text box.

SSL

By default, the Citrix Hypervisor is not SSL-enabled. This indicates that by default, the eG agent communicates with the target hypervisor using HTTP. Accordingly, the SSL flag is set to No by default. If you configure the target hypervisor to use SSL, then make sure that the SSL flag is set to Yes, so that the eG agent communicates with the target hypervisor using HTTPS. Note that a default SSL certificate comes bundled with every Citrix Hypervisor installation. If you want the eG agent to use this default certificate for communicating with an SSL-enabled Citrix Hypervisor, then no additional configuration is required. However, if you do not want to use the default certificate, then you can generate a self-signed certificate for use by the target hypervisor. In such a case, you need to explicitly follow the broad steps given below to enable the eG agent to communicate with the target hypervisor via HTTPS:

  • Obtain the server-certificate for the Citrix Hypervisor
  • Import the server-certificate into the local certificate store of the eG agent

For a detailed discussion on each of these steps, refer to the Troubleshooting section of this document.

Inside View Using

By default, this test communicates with every VM remotely and extracts “inside view” metrics. Therefore, by default, the Inside View Using flag is set to Remote connection to VM (Windows).

Typically, to establish this remote connection with Windows VMs in particular, eG Enterprise requires that the eG agent be configured with domain administrator privileges. In high-security environments, where the IT staff might have reservations about exposing the credentials of their domain administrators, this approach to extracting “inside view” metrics might not be preferred. In such environments therefore, eG Enterprise provides administrators the option to deploy a piece of software called the eG VM Agent on every Windows VM; this VM agent allows the eG agent to collect “inside view” metrics from the Windows VMs without domain administrator rights. Refer to Configuring Windows Virtual Machines to Support the eG Agent’s Inside View Using the eG VM Agent for more details on the eG VM Agent. To ensure that the “inside view” of Windows VMs is obtained using the eG VM Agent, set the Inside View Using flag to eG VM Agent (Windows). Once this is done, you can set the Domain, Admin User, and Admin Password parameters to none.

Webport

By default, in most virtualized environments, the target hypervisor listens on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled Citrix hypervisor, the eG agent, by default, connects to port 443 of the server to pull out metrics, and while monitoring a non-SSL-enabled Citrix hypervisor, the eG agent connects to port 80. Accordingly, the webport parameter is set to 80 or 443 depending upon the status of the ssl flag.  In some environments however, the default ports 80 or 443 might not apply. In such a case, against the webport parameter, you can specify the exact port at which the target hypervisor in your environment listens so that the eG agent communicates with that port.

Packet size

The size of packets used for the test (in bytes)

Packet Count

The number of packets exchanged between the virtual desktop and the user terminal during the test

Timeout

How long after transmission should a packet be deemed lost (in seconds)

Packet Interval

Represents the interval (in milliseconds) between successive packet transmissions during the execution of this test.

Report Unavailability

By default, this flag is set to No. This implies that, by default, the test will not report the unavailability of network connection between a user terminal and a virtual desktop. In other words, if the Packet loss measure of this test registers the value 100% for any user, then, by default, this test will not report any measure for that user; under such circumstances, the corresponding user name will not appear as a descriptor of this test. You can set this flag to Yes, if you want the test to report and alert you to the unavailability of network connection between a user terminal and a virtual desktop.

   
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Avg network delay:

Indicates the average delay between transmission of packet to a VM and receipt of the response to the packet at the source.

Secs

An increase in network latency could result from misconfiguration of the router(s) along the path, network congestion, retransmissions at the network, etc.

Min network delay:

The minimum time between transmission of a packet and receipt of the response back.

Secs

A significant increase in the minimum round-trip time is often a sure sign of network congestion.

Packet loss:

Indicates the percentage of packets lost during transmission from source to target and back.

Percent

Packet loss is often caused by network buffer overflows at a network router or by packet corruptions over the network. The detailed diagnosis for this measure provides a listing of routers that are on the path from the external agent to target server, and the delays on each hop. This information can be used to diagnose the hop(s) that could be causing excessive packet loss/delays.

Network availability of VM:

Indicates whether the network connection is available or not.

Percent

A value of 100 indicates that the VM is connected. The value 0 indicates that the VM is not connected.

Typically, the value 100 corresponds to a Packet loss of 0.