F5 Virtual Servers Test

A virtual server is capable of performing the following:

  • Distribute client requests across multiple servers to balance server load;
  • Apply various behavioral settings to a specific type of traffic;
  • Enable persistence for a specific type of traffic;
  • Direct traffic according to user-written iRules

In addition, virtual servers can also be used in the following ways:

  • Directing traffic to a load balancing pool;
  • Sharing an IP address with a VLAN node;
  • Forwarding traffic to a specific destination IP address;
  • Increasing the speed of processing HTTP traffic;
  • Increasing the speed of processing Layer 4 traffic;
  • Relaying DHCP traffic

Since the virtual servers are able to manage the traffic and divert client requests to servers that are managing fewer requests, poor performance and outages can be avoided. Irregularities in load balancing can cause significant delay in request processing thus affecting the user experience with the load balancing system.To avoid this, you can configure the periodic execution of the F5 Virtual Servers test. For each virtual server configured on the traffic manager, this test continuously monitors the load on the load-balancing virtual 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 : A Big-IP/F5 Local Traffic Manager

Agent deploying the test : An external agent

Outputs of the test : One set of results for each pool configured on a traffic manager

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 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.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite 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
Measurements Description Measurement Unit Interpretation

Data transmitted

Indicates the rate at which data is transmitted from this virtual server during the last measurement period.

MB/Sec

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

Data received

Indicates the rate at which data is received by this virtual server during the last measurement period.

MB/Sec

Packets transmitted

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

Packets/Sec

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

Packets received

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

Packets/Sec

Active connections

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

Number

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

Total connections

Indicates the total number of connections established on this virtual server since the restart of the traffic manager.

Number

 

Connection during the last measure period

Indicates the rate at which connections were established during the last measurement period.

Conns/Sec

 

Connection usage

Indicates the percentage of connections that were used by this virtual server.

Percent

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

Maximum connections established

Indicates the maximum number of connections that were established on this virtual server since the start of the traffic manager.

Number

 

Requests

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

Requests/sec

 

CPU usage

Indicates the percentage of time this virtual server was busy during the past minute.

Percent

A value close to 100 is a cause of concern.

Average time for all connections

Indicates the average time required for establishing all the connections to this virtual server.

Milliseconds

A sudden/gradual increase in the value of this measure may indicate connection issues to the virtual server.