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 external 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 obtains the “inside view” of VMs using the eG VM Agent. Accordingly, the Inside view using flag is set to eG VM Agent by default. The eG VM Agent is a piece of software, which should be installed on every VM on a hypervisor. Every time the eG agent runs this test, it uses the eG VM Agent to pull relevant 'inside view' metrics from each VM. Once the metrics are collected, the eG agent then communicates with each VM agent and pulls these metrics, without requiring administrator privileges. Refer to Configuring the Remote Agent to Obtain the Inside View of VMs for more details on the eG VM Agent.
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 the value of this measure is a cause for concern. Given below are some common reasons for such an anomaly: The network between the VM and the eG external agent is congested. When there is an increase in traffic on the interconnecting network, data transmission can slow down, thereby increasing communication latency. The quality of the network connection between the eG external agent and the VM is sub-par. Poor signal quality, faulty transmission lines, etc. can result in an increase in packet loss and/or network latency. The VM is overloaded. If the VM is very busy, it takes longer to respond to requests, and this will result in an increase in latency. There are problems with network routing between the VM and the eG external agent. A faulty network router, routing loops, etc., can increase network latency. Check the detailed diagnosis of this test to track latency on the first three hops between the agent and the VM. The latency to each hop can be used to determine which hop the problem lies in.
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	A value close to 100% for this measure is a cause for concern. Given below are some common reasons for such an anomaly: The network between the VM and the eG external agent is congested. When there is an increase in traffic on the interconnecting network, packets may be dropped. The quality of the network connection between the eG external agent and the VM is sub-par. Poor signal quality, faulty transmission lines, etc. can result in an increase in packet loss and/or network latency. The VM is overloaded. If the VM is very busy, it takes longer to respond to requests, and this will result in packet drops. There are problems with network routing between the VM and the eG external agent. A faulty network router, routing loops, etc., can increase packet loss. Check the detailed diagnosis of this test to know the hops that are on the path from the external agent to target VM, and the packet loss on each hop. This information can be used to diagnose the hop(s) that could be causing excessive packet loss.
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. The value 0 for this measure could mean that the target VM is either down or too busy, or the interconnecting network is down.