CBR Scaler Statistics Test

The performance of a Citrix Branch Repeater is often judged based on how well it handles its workload – i.e., how well it accelerates traffic over LAN and WAN links and how many connections it has accelerated over a period of time. A sudden increase in workload coupled with improper configuration can be disastrous – not just in terms of branch repeater performance but also in terms of branch user experience with local and wide area networks. It is therefore best to keep track of the variations in the workload of the branch repeater, so that potential overload conditions can be detected, and also monitor key configuration settings such as compression algorithms employed by the branch repeater, so that ineffective configurations can be isolated and reset. The CBR Scaler Statistics test enables these checks. This test continuously tracks the load on the branch repeater, measures the effectiveness of the repeater by reporting the amount of data and connections it has accelerated, and also brings poor compression algorithms to light by revealing changes in compression ratios over time.

Target of the test : A Citrix Branch Repeater

Agent deploying the test : An external agent

Outputs of the test : One set of results for the Citrix Branch Repeater 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.

Port

Refers to the port at which the specified host listens to. By default, this will be NULL.

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 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.

EngineID

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

Load in 1 min

Indicates the average load of the branch repeater during the last minute.

Percent

This measure represents the percentage of processes that are ready to be run. This value is computed by taking the 1-minute load average, multiplying it by 100, and then converting that value to an integer.

You may want to observe changes in the value of this measure over time to understand whether/not there is a consistent increase in workload – if so, it could be indicative of a probable overload.

Load in 5 min

Indicates the average load of the branch repeater during the last 5 minutes.

Percent

This value is computed by taking the 51-minute load average, multiplying it by 100, and then converting that value to an integer.

You may want to observe changes in the value of this measure over time to understand whether/not there is a consistent increase in workload – if so, it could be indicative of a probable overload.

Data transmitted in WAN

Indicates the total amount of accelerated data transmitted over WAN links during the last measurement period.

KB

A high value is desired for these measures, as it denotes high acceleration activity over WAN, which could significantly improve the responsiveness of the WAN links.

A consistent drop in these values could indicate a processing bottleneck with the branch repeater or a misconfiguration that is stalling the repeater’s traffic acceleration efforts.

Data received in WAN

Indicates the total amount of accelerated data received over WAN links during the last measurement period.

KB

Data transmitted in LAN:

Indicates the total amount of accelerated data transmitted over LAN links during the last measurement period.

KB

A high value is desired for these measures, as it denotes high acceleration activity over LAN, which could significantly improve the responsiveness of the LAN links.

A consistent drop in these values could indicate a processing bottleneck with the branch repeater or a misconfiguration that is stalling the repeater’s traffic acceleration efforts.

Data received in LAN:

Indicates the total amount of accelerated data received over LAN links during the last measurement period.

KB

Send compression ratio

Indicates the compression rate of the accelerated data transmitted during the last measurement period.

Percent

One of the techniques that the Citrix Branch repeater uses to accelerate data transmissions and receptions is compression. A compression algorithm scans the data to be compressed, searching for strings of data that match strings that have been sent before. If no such matches are found, the actual data is sent. If a match is found, the matching data is replaced with a pointer to the previous instance. In a very large matching string, megabytes or gigabytes of data can be represented by a pointer containing only a few bytes, and only those few bytes need be sent over the link.

Ideally, the compression algorithm should be able to deliver high compression ratios. So, if the value of these measures drop consistently, it could indicate the usage of a poor compression algorithm. You may then want to consider fine-tuning the compression algorithm to ensure a high compression ratio.

Receive compression ratio

Indicates the compression rate of the accelerated data received during the last measurement period.

Percent

Accelerated connections

Indicates the number of connections that were currently accelerated.

Number

If the number of Accelerated connections is more than the number of Non-accelerated connections, it is a sign of the good health of the branch repeater.

Non-accelerated connections

Indicates the number of connections that were not accelerated currently.

Number

Operational state

Indicates the current operational state of the branch repeater.

 

The values that this measure can report and their corresponding numeric values have been detailed in the table below:

Measure Value

Numeric Value
Up 1
Busy 100
Down 101
License Expired 102

Note:

By default, this measure reports the above-mentioned Measure Values while indicating the operational state of the branch repeater. However, in the graph of this measure, the same will be represented using the corresponding numeric equivalents only.