Interfaces and addresses

lldpcli

Also lldpd, lldp neighbors, cdp neighbors

Reads and sets lldpd: the LLDP and CDP neighbours heard on each card, and what this device announces.

lldpd announces the device on its cards and keeps what it hears from neighbours; lldpcli asks it. show neighbors lists one block per card with the neighbour's chassis, name and port; details adds every TLV, LLDP-MED's included. configure changes what is announced, live.

lldpcli command usage

lldpcli show neighbors [summary|details] [ports PORT]
lldpcli show interfaces | statistics | configuration
lldpcli configure ports PORT lldp status rx-and-tx|rx-only|tx-only|disabled
lldpcli update

Options

summary: name, chassis and port of each neighbour only
details: every TLV the neighbour sent
ports PORT: one card only
update: announce now instead of at the next interval

lldpcli examples

lldpcli show neighbors summary: Who is at the other end of each card.
lldpcli show neighbors details | grep -A5 'Network Policy': The voice VLAN, priority and DSCP an LLDP-MED switch hands out.
lldpcli configure ports laptop lldp status rx-only: Stops announcing on one port, still listening there.

Reading the output

$ lldpcli show neighbors summary
Interface:    gateway, via: CDPv2
  Chassis:
    ChassisID:    local gateway
    SysName:      gateway
  Port:
    PortID:       ifname eth0
    PortDescr:    eth0
    TTL:          20

via: names the protocol the entry was heard over: LLDP, CDPv1 or CDPv2.
TTL: seconds left before the entry is forgotten unless a new announcement arrives.

Pitfalls

An entry stays until its TTL runs out: a neighbour that went quiet is still listed for a while.
lldpd skips virtual cards unless they are named with -I.

Run it on real machines