How does the SPECTRUM "Traffic Resolution" AutoDiscovery Modeling Protocol work?

Products

• Spectrum
• Network Observability

Issue/Introduction

How does the SPECTRUM "Traffic Resolution"  AutoDiscovery Modeling Protocol work?

Resolution

The "Define the Modeling Options" section of the documentation defines the Traffic Resolution AutoDiscovery Modeling Protocol as follows:

Traffic Resolution - Determines whether Discovery uses network traffic data when determining connections between interfaces. Often, letting Discovery to use the traffic data eliminates the need to model Fanout segments.

The following is a more detailed explanation of how the Traffic Resolution AutoDiscovery Modeling Protocol works.

AutoDiscovery will first use the discovery protocols, like SAT, CDP, Spanning Tree etc, to map layer-2 port connectivity.  If for some reason, AutoDiscovery could not determine the exact port level connection among 3 or more ports, a Fanout model would be created to represent this connection and then AutoDiscovery would invoke the Traffic Resolution protocol if selected.

For each port connected to this Fanout, AutoDiscovery will read the ifInOctets and ifOutOctets attributes from the interfaces mib.  AutoDiscovery will the wait for one minute and read the ifInOctets and ifOutOctets attributes from the interfaces mib again.  AutoDiscovery will then calculate the delta of ifInOctets and ifOutOctets for each port connected to the Fanout.  If the delta of one port's ifInOutOctet has a close match with delta of another port's ifOutOctets, AutoDiscovery will assume the ports are connected and create the proper associations in the SPECTRUM database.

Additional Information

How will you know if this is needed?  You can enable Spectrum Autodiscovery Debug on the VNM - Component Detail - AutoDiscovery Control - Debug - set to Enabled.

Right click the model - Reconfiguration - Discover Connections.

Once complete log into the SpectroSERVER and navigate to the $SPECROOT/SS folder which will now have an ADiscDebug_<date> file.

Review that file and look for entries noting "potential connections" for the interfaces you are concerned about. 

For example:

Port device1_Ethernet1/6(ifType=6) has 2 potential connections:
   Port device1_Ethernet1/6(ifType=6) <-PC-> Port device2_Ethernet1/1(ifType=6) 
   Port device1_Ethernet1/6(ifType=6) <-PC-> Port device2_mgmt0(ifType=6) 

Unable to map the exact connections among these ports:

   Port device1_Ethernet1/6(ifType=6)  (Fanout port)
   Port device2_Ethernet1/1(ifType=6)  (Fanout port)
   Port device2_mgmt0(ifType=6)  (Fanout port)

Enable Traffic Resolution on the VNM

Run your discovery again and you will now see "Traffic resolution" in the log and the connection will be made:

Apr 16 14:50:53   Mapping Fanout port group thru Traffic resolution:   Port device2_mgmt0(ifType=6)  (Fanout port)
   Port device1_Ethernet1/6(ifType=6)  (Fanout port)
   Port device2_Ethernet1/1(ifType=6)  (Fanout port)