Top Sources By Interfaces Test

How often should the test be executed

The host for which the test is to be configured.

By default, for each interface that the target Netflow device supports, this test reports metrics for only the top-10 sources that handle over 3% of the total traffic on that interface. Also, by default, the test will report detailed diagnostics for only the top-5 sources that handle over 3% of the total traffic on that interface. This default setting enables network administrators to focus on the abnormal flows alone. This behavior is governed by the default setting of the Filter By, Minimum Flow Percent, Report Top N Flows, and Show DD for Top N Flows parameters. By default, the Filter By option is set to %Traffic and the Minimum Flow Percent is set to 3 (%). You can increase or decrease the Minimum Flow Percent depending upon the level of traffic that you deem as abnormal. Also, by default, the Report Top N Flows is set to 10 and Show DD for Top N Flows is set to 5. You can increase or decrease the value of these two parameters depending upon the level of visibility you require.

You can also override the Filter By default setting and have this test report real-time metrics and detailed diagnostics for only those sources (per interface) that use over a configured percentage of bandwith resources when transmitting data. For this, set Filter By to Bandwidth Used and configure a bandwidth usage limit (in %) against Minimum Flow Percent. This way, administrators can focus on only those sources that generate bandwidth-intensive traffic.

Provide a comma-separated list of sources that you want excluded from monitoring. For example, your specification can be, 192.168.10.45, 192.168.10.71,192.168.10.220. You can even provide patterns of source IP addresses as a comma-separated list - for instance, 192.168.10.*,192.168.8.1*1, *.168.9.45. Alternatively, you can provide a range of source IP addresses. For example, 192.168.10.32-192.168.10.45.

Note:

Sources can be represented using IP addresses only and not host names.

Provide a comma-separated list of destinations that you want excluded from monitoring. For example, your specification can be, 192.168.10.45, 192.168.10.71,192.168.10.220. You can even provide patterns of destination IP addresses as a comma-separated list - for instance, 192.168.10.*,192.168.8.1*1, *.168.9.45. Alternatively, you can provide a range of source IP addresses. For example, 192.168.10.32-192.168.10.45.

Note:

Destinations can be represented using IP addresses only and not host names.

Provide a comma-separated list of interfaces that you want excluded from monitoring. For example, your specification can be, FastEtherNet0/0, FastEthernet0/1,FastEtherNet0/2. You can even provide patterns of interfaces as a comma-separated list - for instance, *ethernet*,Fast*.

This test captures statistics on traffic that originates from source hosts, where each host is by default represented by its IP address in the eG monitoring console. Accordingly, this flag is set to No by default. You can set this flag to Yes so that the names of the individual hosts are displayed in the eG monitoring console instead of their IP addresses.

By default, the Both Traffic option is chosen from the Show Traffic drop-down list. This implies that by default, this test will report metrics on both input and output traffic for every interface. In some environments, the traffic flowing out of one interface (i.e., output traffic) can subsequently flow into another interface (i.e., input traffic). In such environments, if the eG agent is configured to report on both input and output traffic, duplication of metrics may become inevitable. As a result, administrators may not be able to assess the real data load on any interface. To avoid this, you can override the default setting of the Show Traffic parameter by choosing one of the following options:

• IN Traffic Only: Choosing this option will instruct the test to report only metrics on input traffic per interface.

• OUT Traffic Only: Choose this option if you want the test to report only metrics on output traffic per interface.

By default, this flag is set to No. This means that by default, this test will report metrics for every interface that the target NetFlow device supports. If you want, you can configure this test to report metrics for every Interface_Type:Interface_Name pair. For this, set this flag to Yes. Doing so will help you quickly determine what is the type of every interface, and whether the interface type influences traffic flow and bandwidth consumption in any way.

By default, this flag is set to Yes, indicating that the test will ignore the sources of all the intranet traffic on the router. If you want the test to report metrics pertaining to the sources of local traffic as well, set this flag to No.

Network latencies and processing bottlenecks can sometimes cause netflow records to be transmitted slowly to the NetFlow collector. In such a situation, you can instruct the collector to either process or ignore the delayed NetFlow records. If you want the metrics reported to pertain to current NetFlow records only, then you may choose to ignore the delayed records. In this case, set this flag to No. If you want old NetFlow records to also be considered when identifying top sources and reporting their traffic statistics, then set this flag to Yes. Typically, any NetFlow record that takes 10 minutes or over to reach the NetFlow collector is deemed a tainted/delayed record.

By default, NetFlow is designed to process all IP packets on an interface. This is why, the Sampling flag is set to No by default. In some environments however, e.g. on Internet backbones, processing all IP packets can be too costly, due to the extra processing required for each packet and large number of simultaneous flows. This is where sampling is useful. In such environments, set the Sampling flag to Yes.

Once this is done, then each interface will process only 1 packet out of a configured number of packets. Specify the number of packets from which this 1 packet should be picked in the Sampling Rate text box. For instance, to pick 1 out of 1000 packets for sampling, set the Sampling Rate to 1000. Where Sampling is enabled, all NetFlow metrics - particularly, metrics on traffic volume - will be adjusted based on the Sampling Rate you specify.

The port at which the monitored target exposes its SNMP MIB; the default is 161.

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.

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.

This parameter appears only when v3 is selected as the SNMP. 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 the Username parameter. 

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.

Specify the password that corresponds to the above-mentioned Username. This parameter once again appears only if the SNMPversion selected is v3.

Confirm the Authpass by retyping it here.

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

This flag appears only when v3 is selected as the SNMPversion. By default, the eG agent does not encrypt SNMP requests. Accordingly, this flag is set to No by default. To ensure that SNMP requests sent by the eG agent are encrypted, select the Yes option. 

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

Specify the encryption password here.

Confirm the encryption password by retyping it here.

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.

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.

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.

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD frequency.