#Neighbor discovery

File: src/topics/neighbor.j. Path: /ip/neighbor (NEIGHBOR_PATH). Reference: cheatsheet.

The router collects the discovery announcements of directly connected devices: MNDP (MikroTik), CDP (Cisco) and LLDP (most vendors). The list shows the switch on ether2 or the upstream router without a scan. Devices behind another router never appear.

#Examples

def ns as list of mt.Neighbor init mt.neighbors($c);
for (def n in $ns) {
    io.printf("%s: %s %s (%s) at %s on %s\n",
        $n.identity, $n.platform, $n.board, $n.version, $n.address, $n.interfaceName);
}

def up as list of mt.Neighbor init mt.neighborsOn($c, "ether1");
for (def n in $up) { io.printf("upstream: %s (%s)\n", $n.identity, $n.address); }

#Pitfalls

• A neighbor with an empty address was heard at layer 2 but has no IP on this segment. That is normal.
• The router hears (and is heard) only on interfaces where discovery is enabled. It is on by default; a hardened config may restrict it under /ip/neighbor/discovery-settings (generic verbs). Turn it off on untrusted and WAN interfaces: it announces your model and version.
• Devices that do not announce themselves (most PCs and servers) never appear. For IP-to-MAC presence use the ARP table.

See also: services.md for locking down the WAN side.