Real Server Test

Real servers are those that are bound to a virtual server in a server farm of the load balancer. Whenever a client request is received, the virtual server bound to the real server responds to those requests by channelizing the requests to the real servers that are currently available. If the real servers are experiencing any technical glitch or a slowdown or if the real servers are currently overloaded, the target load balancer may not be effective in responding to the client requests thus causing inconsistencies in the load balancing functionality. To avoid such inconsistencies, it is necessary to monitor the request processing ability of the real servers round the clock. This is where the Real Server test exactly helps!

For each real server grouped on the virtual server that is configured on the target load balancer, this test reveals how well each server processes client requests. In addition, this test detects inconsistencies in load-balancing early on and warns administrators of possible deviations proactively.

Target of the test : A Load Balancer VA R20

Agent deploying the test : An external agent

Outputs of the test : One set of results for each Virtual server:Real server combination on the target load balancer being monitored

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The IP address of the host for which this test is to be configured.

SNMPPort

The port at which the monitored target exposes its SNMP MIB; The default value 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 storage node. 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.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Current connections

Indicates the number of connections handled by this real server during the last measurement period.

Number

This measure is a good indicator of load on the real server.

The detailed diagnosis of this measure lists the IP address and the port number of the real server through which the server is associated with the virtual server.

Received packets

Indicates the number of packets received by this real server during the last measurement period.

Number

Compare the value of this measure across the real servers to figure out the real server that is receiving the maximum number of packets.

Transmitted packets

Indicates the number of packets transmitted by this real server during the last measurement period.

Number

Compare the value of this measure across the real servers to figure out the real server that is transmitting the maximum number of packets.

Received data

Indicates the amount of data received by this real server during the last measurement period.

KB

Compare the value of this measure across the real servers to figure out the real server that is receiving the maximum amount of data.

Transmitted data

Indicates the amount of data transmitted by this real server during the last measurement period.

KB

Compare the value of this measure across the real servers to figure out the real server that is transmitting the maximum amount of data.

Received packet rate

Indicates the rate at which packets were received by this real server.

Packets/sec

 

Transmitted packet rate

Indicates the rate at which packets were transmitted by this real server.

Packets/sec

 

Received data rate

Indicates the rate at which data was received by this real server.

KB/sec

 

Transmitted data rate

Indicates the rate at which data was transmitted by this real server.

KB/sec