SmartMIB Small Solution:

Ethernet Interface Traffic and Error Statistics

(SM-SmallSol006)

Solution Overview:

This small management solution focuses on managing ONLY those interfaces that are NOT in an administrative down state as is set by the network administrator on the managed network devices.

The solution defines a set of modules that reads the MIB interface tables of the managed elements and filters those interfaces that are of type Ethernet and further segments those interfaces into ‘Normal’ speed interfaces (20 Mbps and less) and ‘High’ Speed interfaces (more than 20 Mbps).

Following are the equations that should be used to calculate link traffic utilizations in each direction:

Inbound Traffic Utilization

Outbound Traffic Utilization

Integrating the Overhead into the formulas above will give us the Data Utilization:

Inbound Data Utilization

Outbound Data Utilization

Where;

TotalInPkts:

Is the total number of packets inbound on the particular interface. The packets could include unicast, multicast, and broadcast packet types depending on the type of interface.

TotalOutPkts:

Is the total number of packets outbound on the particular interface. The packets could include unicast, multicast, and broadcast packet types depending on the type of interface.

PktOVHead:

Is the traffic overhead bits which includes interpacket delay bits and preamble bits. Overhead is also interface type dependant.

The Time Interval used in the formulas above deserves a closer look. While it is indeed the time difference between each Octets counter’s consecutive poll cycles; if used in the formulas above, it will compromise the accuracy of the final calculated value due to the ’time skew’ between both poll cycles. Hence the actual time used in the formulas above should be derived from device being polled and not from the host NMS server.

In looking more closely at link utilization; overhead traffic, broadcast and multicast traffic, are indeed independently measured and could be then compared to the overall utilization in each link direction by viewing the relevant Graphs simultaneously.

The user has the choice to graph all of the following calculated objects:

• InTrafficUtilization and OutTrafficUtilization: representing the Inbound and Outbound traffic load utilizations respectively.

• InDataUtilization and OutDataUtilization: representing the Inbound and Outbound Data load utilizations respectively.

• InThroughput and OutThroughput: representing the Inbound and Outbound traffic load throughputs respectively.

• Other lower level counters and frame overhead counts could also be plotted by the administrator. (Some of those counters are non database or are removed from the database after each new run of the polling! Hence it is important to plan what graphs are to be presented and check that the corresponding variable is a database defined variable and is kept in the database. The management script below has to be modified accordingly).
   

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