Virtual Server Test

Each real server group is mapped to a virtual server. The virtual server receives incoming client requests , uses a load-balancing algorithm to select an available real server in the group, and routes the requests to the selected real server.

Since application requests are front-ended by a virtual server, tracking the session load on a virtual server will reveal the load on the applications running on the real servers mapped to that virtual server. This also means that if the virtual server experiences a processing bottleneck, it is bound to impact load distribution and processing by the real servers, which will consequently affect user experience with the applications in the backend. To understand the load on your applications and to proactively detect any potential slowness that your applications may experience, it is good practice to continuously monitor each virtual server. This is exactly what the Virtual Server test does!

This test auto-discovers the virtual servers that are mapped to real server groups. For each virtual server, the test then reports the session load on the server and the rate at which each server processes data. Additionally, the test also reports the count and names of real servers and server groups mapped to each virtual server. This way, you can figure out which are the applications load-balanced by the virtual servers, and will be impacted by performance issues in the virtual servers.

Target of the test : A Radware Alteon Load Balancer

Agent deploying the test : An external agent

Outputs of the test : One set of results for each virtual server

Configurable parameters for the test
Parameter	Description
Test period	How often should the test be executed
Host	The IP address of the Radware Alteon load balancer that is being monitored.
SSH Port	Besides SNMP, this test also uses the Radware CLI to pull metrics on real servers. To run the CLI commands, the test first needs to establish an SSH connection with the Radware Alteon load balancer. To enable the test to establish this connection, specify the SSH Port here.
SSH Username, SSH Password, and Confirm Password	As stated earlier, this test also uses the Radware CLI to pull metrics on real servers. To use the CLI, the test first needs to connect to the Radware Alteon load balancer via SSH, and then run commands using CLI. For running the commands, this test requires the privileges of a valid SSH user with permission to run the CLI commands. Specify the user name and password of such a user against SSH UserName and SSH Password text boxes, and confirm the password by retyping it in the Confirm Password text box.
SNMPPort	The port at which the monitored target exposes its SNMP MIB; the default is 161.
SNMPVersion	By default, the eG agent supports SNMP version 1. Accordingly, the default selection in the SNMPversion list is v1. However, if a different SNMP framework is in use in your environment, say SNMP v2 or v3, then select the corresponding option from this list.
SNMPCommunity	The SNMP community name that the test uses to communicate with the firewall. This parameter is specific to SNMP v1 and v2 only. Therefore, if the SNMPVersion chosen is v3, then this parameter will not appear.
Username	This parameter appears only when v3 is selected as the SNMPVersion. SNMP version 3 (SNMPv3) is an extensible SNMP Framework which supplements the SNMPv2 Framework, by additionally supporting message security, access control, and remote SNMP configuration capabilities. To extract performance statistics from the MIB using the highly secure SNMP v3 protocol, the eG agent has to be configured with the required access privileges – in other words, the eG agent should connect to the MIB using the credentials of a user with access permissions to be MIB. Therefore, specify the name of such a user against this parameter.
Context	This parameter appears only when v3 is selected as the SNMPVersion. An SNMP context is a collection of management information accessible by an SNMP entity. An item of management information may exist in more than one context and an SNMP entity potentially has access to many contexts. A context is identified by the SNMPEngineID value of the entity hosting the management information (also called a contextEngineID) and a context name that identifies the specific context (also called a contextName). If the Username provided is associated with a context name, then the eG agent will be able to poll the MIB and collect metrics only if it is configured with the context name as well. In such cases therefore, specify the context name of the Username in the Context text box. By default, this parameter is set to none.
AuthPass	Specify the password that corresponds to the above-mentioned Username. This parameter once again appears only if the SNMPversion selected is v3.
Confirm Password	Confirm the AuthPass by retyping it here.
AuthType	This parameter too appears only if v3 is selected as the SNMPversion. From the AuthType list box, choose the authentication algorithm using which SNMP v3 converts the specified username and password into a 32-bit format to ensure security of SNMP transactions. You can choose between the following options: MD5 - Message Digest Algorithm SHA - Secure Hash Algorithm SHA224 - Secure Hash Algorithm 224 bit SHA256 - Secure Hash Algorithm 256 bit SHA384 - Secure Hash Algorithm 384 bit SHA512 - Secure Hash Algorithm 512 bit
EncryptFlag	This flag appears only when v3 is selected as the SNMPVersion. By default, the eG agent does not encrypt SNMP requests. Accordingly, the this flag is set to No by default. To ensure that SNMP requests sent by the eG agent are encrypted, select the Yes option.
EncryptType	If the EncryptFlag is set to Yes, then you will have to mention the encryption type by selecting an option from the EncryptType list. SNMP v3 supports the following encryption types: DES - Data Encryption Standard 3DES - Triple Data Encryption Standard AES - Advanced Encryption Standard AES128 - Advanced Encryption Standard 128 bit AES192 - Advanced Encryption Standard 192 bit AES256 - Advanced Encryption Standard 256 bit
EncryptPassword	Specify the encryption password here.
Confirm Password	Confirm the encryption password by retyping it here.
Timeout	Specify the duration (in seconds) within which the SNMP query executed by this test should time out in this text box. The default is 10 seconds.
Data Over TCP	By default, in an IT environment, all data transmission occurs over UDP. Some environments however, may be specifically configured to offload a fraction of the data traffic – for instance, certain types of data traffic or traffic pertaining to specific components – to other protocols like TCP, so as to prevent UDP overloads. In such environments, you can instruct the eG agent to conduct the SNMP data traffic related to the monitored target over TCP (and not UDP). For this, set this flag to Yes. By default, this flag is set to No.
Engine ID	This parameter appears only when v3 is selected as the SNMPVersion. Sometimes, the test may not report metrics when AES192 or AES256 is chosen as the Encryption type. To ensure that the test report metrics consistently, administrators need to set this flag to Yes. By default, this parameter is set to No.
Detailed Diagnosis	To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option. The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled: The eG manager license should allow the detailed diagnosis capability Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.

Measurements made by the test
Measurement	Description	Measurement Unit	Interpretation
Number of groups associated	Indicates the number of real server groups associated with this virtual server.	Number	Use the detailed diagnosis of this measure to know which groups and real servers are associated with the virtual server.
Number of real servers associated	Indicates the number of real servers associated with this virtual server.	Number	Use the detailed diagnosis of this measure to know which groups and real servers are associated with the virtual server.
Current session	Indicates the number of sessions currently handled by this virtual server.	Number	Compare the value of this measure across virtual servers to identify the server that is handling the maximum number of sessions.
Total sessions	Indicates the total number of sessions handled by this virtual server from the time it was started.	Number
Data transfer rate	Indicates the rate at which data was handled by this virtual server.	MB/Sec	Compare the value of this measure across the virtual servers to know which server is the slowest in processing requests. Such a server could be experiencing a processing bottleneck. You may want to investigate the reasons for the slowness and fix it before it impacts load distribution and processing by the real servers.