Over the years a number of customers have asked the question: "What SNMP OIDs does Spectrum use to manage my network?" It turns out this simple question has a fairly complex answer that depends on:
To begin addressing this it is good to understand the scope of the question. CA Technology's Spectrum product has over 2600 MIBs imported into its database and application models for over 700 of these MIBs. So in practice it has been nearly impossible to tell customers in advance exactly which SNMP OIDs Spectrum will request in their network.
Since this question needs an answer, creative approaches need to be developed to meet this need. This tech bulletin outlines ways customers can answer this in their own environment.
Although using a Packet Analyzer to capture all traffic can potentially answer this question, its use has some limitations:
For this reason an approach using only Spectrum is considered in this tech bulletin.
There are tools built into Spectrum which permit the run time tracing of SNMP packets which are issued by the SpectroSERVER. This has been a standard part of the product for since very early versions of the product. Additional "tools" described in this bulletin are needed to parse the SNMP debug output. These tools are simple UNIX commands and scripts which the user can run on trace data. The information produced by the SNMP Stack debugging contains volumes of data which is not relevant to answering the question above. The tools filter that out and produce more useful information
The commands (or scripts) recommend are standard on UNIX systems and can be obtained on the Windows platform as well. These were developed and tested with Cygwin utilities on a Windows 7 platform.
The process of capturing all OIDs used includes the following steps:
There are potentially two possible mechanisms to enable / disable SNMP Communications Tracing depending on which version of Spectrum is in use. All Spectrum versions support the CLI based action which is sent via the following command:
update action=0x10314 mh=<VNM_MH> # to Enable Tracing update action=0x10315 mh=<VNM_MH> # to Disable Tracng
Another alternative for customers of Spectrum 9.2.2 (or later) is to use the One Click UI to enable and disable the tracing. This can be done using the following controls on the VNM Information View:
<Please see attached file for image>
The user should set the value of "SNMP Stack" to "Enabled" to begin the tracing process. After that the operation under test (Discovery, Modeling, Device Reconfiguration, NCM firmware capture, etc) should be performed
The following UNIX commands are used to parse the SNMP debugging output:
egrep "^\ Device IP: | \ [0-9]: " VNM.OUT | sed "s/ Varbinds (.)://" > SnmpRequests.txt egrep -v Device SnmpRequests.txt | sed "s/ .*://" | sort -u > SnmpOIDs.txt
It is best to copy and paste these into a script to be executed since the space characters may not be obvious.
As mentioned the basic output of the SNMP Request tracing is extensive. This output should be contained in the file:
The script (or individual commands) should be run in the $SPECROOT/SS directory and they produce two files:
SnmpRequests.txt - listing of all OIDs requested by device in time ordered sequence
SnmpOIDs.txt - a sorted list of all unique OIDs requested during the test
These text files have the following contents:
SnmpRequests.txt Device IP: 22.214.171.124 0: 126.96.36.199.188.8.131.52.184.108.40.206.5.2 Device IP: 220.127.116.11 0: 18.104.22.168.22.214.171.124.1.1 1: 126.96.36.199.188.8.131.52.1.2 2: 184.108.40.206.220.127.116.11.1.3
SnmpOIDs.txt 18.104.22.168.22.214.171.124.0 126.96.36.199.188.8.131.52.0 184.108.40.206.220.127.116.11.0 18.104.22.168.22.214.171.124.0 126.96.36.199.188.8.131.52.0
Using Spectrum's built-in debugging and some scripting it should be possible to analyze SNMP requests for nearly any situation. Although the VNM.OUT may contain significant information, the tools and techniques presented should assist the user in extracting the desired information.
An important caveat of this work is that it is still not possible to tell customers completely in advance what OIDs Spectrum will use. This approach requires access to a live network with devices modeled in Spectrum. But the intent is that once this process is executed in the customer environment they will have the information for further use. This includes
Later versions of Spectrum the SNMP Stack Debug can be turned on from the VNM Model -> Dynamic Debugging