Network Topology Mapping Explained

Wed, 24 Jun 2026 00:00:00 +0000

Network topology mapping is the process of discovering and visualizing how devices, endpoints, and services connect across a network. It captures both physical (Layer 2) relationships - which switch port links to which device - and logical (Layer 3) relationships - how subnets, routes, and autonomous systems reach each other. A topology map can range from a hand-drawn diagram to a live, continuously updated graph built from protocol data such as LLDP, CDP, ARP, FDB, OSPF, and BGP.

Stale FDB/MAC tables: why endpoint location is wrong

Mon, 01 Jan 0001 00:00:00 +0000

Your topology platform says endpoint aa:bb:cc:dd:ee:ff is on switch port Gi1/0/24. Your security team sends someone to that port. The endpoint is not there. It moved hours ago, or it went offline, or it vMotioned to a different host. The FDB entry was stale and the platform presented it as current.

The Forwarding Database (FDB), also called the MAC address table or CAM table, maps MAC addresses to switch ports. Topology inference engines use FDB data, cross-referenced with ARP tables and CDP/LLDP neighbor data, to deduce where endpoints are physically connected. The inference is probabilistic. It degrades as input data freshness degrades.

FDB / MAC Forwarding Topology on Netdata

Network Topology Mapping Explained

Stale FDB/MAC tables: why endpoint location is wrong