Net-SNMP Layer 3 visibility

[carrot]

Hi folks

I'm trying to find a good explanation for the "Layer 3 visibility" switch in Net-SNMP.  What does this actually do?  I understand network layers, just not sure exactly how this applies here. 

Thanks

[proctor]

Searched for that as well. The only hint I found [1] is the following:

"Layer 2 visibility covers physical connections: switch ports, VLANs, MAC addresses, and access point associations. Layer 3 visibility covers logical connections: IP addresses, routing paths, subnets, and gateway relationships. A tool that only provides Layer 3 maps cannot tell you which physical switch port a specific device is connected to. A tool that only provides Layer 2 maps cannot help you trace a routing problem."

[1]  https://blog.domotz.com/all/network-visualization-tools/  -  (search page for "Layer 3 Visibility")

[Patrick M. Hausen]

This setting sets sysServices to 76 while the setting without Layer 3 visibility checked is 72. The sysServices parameter in snmpd.conf populates the matching OID telling a network management system which services the managed host runs.

https://oidref.com/1.3.6.1.2.1.1.7

72 means applications and end-to-end
76 means applications, end-to-end and IP

HTH,
Patrick