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 XenServer host

Agent deploying the test : An internal/remote agent

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

Configurable parameters for the test
  1. Test period - How often should the test be executed
  2. Host - The host for which the test is to be configured.
  3. port - The port at which the specified host listens. By default, this is NULL.
  4. XEN user - To enable the eG agent to connect to the XenServer API for collecting statistics of interest, this test should login to the XenServer 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 XenServer:

    • Modify the target XenServer’s configuration in the eG Enterprise system. For this, follow the Infrastructure -> Components -> Add/Modify menu sequence, pick Citrix XenServer as the Component type, and click the Modify button corresponding to the target XenServer.
    • 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.

  5. xen password - The password of the specified xen user needs to be mentioned here.
  6. confirm password - Confirm the xen password by retyping it here.
  7. ssl - By default, the Xen Server is not SSL-enabled. This indicates that by default, the eG agent communicates with the XenServer using HTTP. Accordingly, the ssl flag is set to No by default. If you configure the XenServer to use SSL, then make sure that the SSL flag is set to Yes, so that the eG agent communicates with the XenServer using HTTPS. Note that a default SSL certificate comes bundled with every XenServer installation. If you want the eG agent to use this default certificate for communicating with an SSL-enabled XenServer, 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 XenServer. In such a case, you need to explicitly follow the broad steps given below to enable the eG agent to communicate with the XenServer via HTTPS:

    • Obtain the server-certificate for the XenServer
    • 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.

  8. webport - By default, in most virtualized environments, the XenServer listens on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled XenServer, the eG agent, by default, connects to port 443 of the server to pull out metrics, and while monitoring a non-SSL-enabled XenServer, 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 XenServer in your environment listens so that the eG agent communicates with that port.
  9. 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 Section 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.
  10. Packetsize - The size of packets used for the test (in bytes)
  11. Packetcount - The number of packets to be transmitted during the test
  12. Timeout - How long after transmission should a packet be deemed lost (in seconds)
  13. PacketInterval- Represents the interval (in milliseconds) between successive packet transmissions during the execution of the network test for a specific target.
  14. reportunavailability – By default, this flag is set to No. This implies that, by default, the test will not report the unavailability of network connection to any VM. In other words, if the Network availability of VM measure of this test registers the value 0for any VM, then, by default, this test will not report any measure for that VM; under such circumstances, the corresponding VM 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 the network connection to a VM. 
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.