LLDP Topology Discovery With OTserver
Overview
Link Layer Discovery Protocol (LLDP) lets neighboring network devices advertise chassis and port identity. OTserver reads the LLDP data already held by an SNMP agent and turns usable neighbor records into topology links between MAC-identified assets.
How OTserver discovers LLDP topology
The scanner uses the configured SNMP profile to walk the standard LLDP remote-systems table under 1.0.8802.1.1.2.1.4.1.1. It also collects LLDP local and extension trees under 1.0.8802.1.1.2.1.5, including the 32962 and 4623 branches, as raw evidence.
For each remote entry, OTserver correlates the time-mark/index data, local port, chassis subtype and ID, remote port, and remote system name. A topology link is created when the local asset has a known MAC and the remote chassis ID is explicitly encoded as a MAC address.
Evidence extracted
| OTserver topology evidence | LLDP remote-table field |
|---|---|
| Local endpoint | ARP-correlated local MAC and LLDP local port number |
| Remote endpoint | Chassis MAC address |
| Remote device name | Remote system name |
| Remote port | Remote port description/identifier |
| Provenance | SNMP profile and LLDP observation source |
Entries without a MAC-form chassis ID stay in raw SNMP evidence rather than being attached to the wrong asset.
Security and read-only safety
OTserver does not transmit LLDP advertisements or change switch neighbor tables. It reads LLDP MIB data with SNMP WALK operations and never sends SNMP SET. Use a read-only SNMPv3 account where possible and keep the LLDP toggle disabled where topology collection is not authorized.
Frequently asked questions
Does OTserver capture raw LLDP Ethernet frames?
No. The current scanner reads LLDP neighbor tables through SNMP on UDP 161; it therefore needs a valid SNMP profile for the target device.
Why are some LLDP neighbors not turned into links?
OTserver only creates a link when the remote chassis subtype says the chassis ID is a MAC address. This avoids inventing asset identity from names, arbitrary strings, or IP addresses.
Compare all supported discovery protocols or read about SNMP inventory discovery.