A10 Servers Test

Physical servers a.k.a Real servers are those that are bound to a virtual server in a server farm of the A10 Application Delivery Controller. 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. Since multiple VIPs can be pointed to the same set of real servers, having a good number of supported VIPs presents more flexibility in the architecture and design of the site or application. There may be up to 100 real servers connected to a single virtual IP and the same set of real servers can be pointed to multiple Virtual IPs to provide more flexibility in the architecture and design of the A10 Application Delivery Controller. The A10 Application Delivery Controller installed in large environments often receives thousands of client requests per second, which should be responded without any time delay. In such cases, the virtual IP sends the requests continuously to the available real servers bound to it. If the real server is experiencing any technical glitch or a slowdown or if the real server is currently overloaded, the A10 Application Delivery Controller 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 health and the request processing details of the real servers. This is where the A10 Servers test exactly helps!

For each real server configured on the A10 Application Delivery Controller, this test continuously monitors the health of the real servers and 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 : An A10 Application Delivery Controller

Agent deploying the test : An external agent

Outputs of the test : One set of results for each server load balanced using the target A10 Application Delivery Controller.

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed

Host

The IP address of the A10 Application Delivery Controller that is being monitored.

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

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 this 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
  • AES – Advanced Encryption Standard

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.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Health status

Indicates the current health of this real server.

 

The values of this measure and their corresponding numeric values are listed below:

Measure Value Numeric Value
Disabled 0
Up 1
Down 2

Note:

By default, this measure reports one of the Measure Values listed in the table above to indicate status of this real server. In the graph of this measure however, the real server status will be represented using the numeric equivalents.

Data transmitted

Indicates the rate at which data was transmitted from this real server during the last measurement period.

MB/Sec

Compare the values of these measures across nodes to identify the node that is handling maximum traffic.

Data received

Indicates the rate at which data was received by this real server during the last measurement period.

MB/Sec

Packets transmitted

Indicates the rate at which the packets were transmitted from this real server during the last measurement period.

Packets/Sec

Compare the value of these measures across the real servers to identify the real server that is experiencing the maximum traffic.

Packets received

Indicates the rate at which packets were received by this real server during the last measurement period.

Packets/Sec

Active connections

Indicates the number of connections that are currently active on this real server.

Number

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

Total connections

Indicates the total number of connections established on this real server since the start of the A10 Application Delivery Controller.

Number

 

Connection rate

Indicates the rate at which the connections were established on this real server during the last measurement period.

Conns/Sec

A sudden increase in the value of this measure indicates an increase in the load on the real server.

Connection usage

Indicates the percentage of connections used by this real server.

Percent

A value close to 100% indicates that the real server is currently overloaded.

Persistent connections

Indicates the number of connections that were persistent on this real server.

Number

TCP connections that are kept open after transactions complete are called persistent connections. . Persistent connections stay open across transactions, until either the client or the server decides to close them. These connections when reused can significantly reduce the overload on the new connections to the real server.

Peak connections

Indicates the maximum number of connections that were established on this real server since the start of the A10 Application Delivery Controller.

Number

 

L7 requests

Indicates the number of L7 requests currently processed by this real server.

Number

Both these measures serve as effective pointers to the L7 requests processing in the A10 Application Delivery Controller.

Layer-7 load balancing, also known as application-level load balancing, is to parse L7 requests in application layer and distribute L7 requests to the servers based on different types of request content, so that it can provide quality of service requirements for different types of content and improve overall performance.

L7 request rate

Indicates the rate at which the L7 requests were processed by this real server.

Requests/Sec

Successful L7 requests

Indicates the number of L7 requests that were processed successfully by this real server.

Number

Ideally the value of this measure should be high.