ArubaOS-CX LLDP: Transmit, Receive and Verification

ArubaOS-CX switches run the Link Layer Discovery Protocol (LLDP) agent on every active interface by default, including the out-of-band management (OOBM) port. Even so, real networks need deliberate LLDP configuration: disabling it on edge ports that face untrusted devices, controlling which ports transmit and which only listen, tuning advertisement timers, and reading neighbor information when you troubleshoot cabling or voice-VLAN issues. This guide explains the ArubaOS-CX LLDP command set with working CLI examples and the verification commands used on the CX family, from 4100i edge switches to 8360 data center switches.

LLDP Agent Defaults on ArubaOS-CX

LLDP is enabled globally and per interface by default on all active interfaces, with a 30-second transmit interval, a hold-time multiplier of 4, a 2-second transmit delay, and a 2-second reinit timer. If LLDP was disabled, re-enable the agent globally in configuration mode:

switch(config)# lldp

To turn the agent off across the switch, use the no lldp form of the command.

Controlling LLDP Transmit and Receive per Port

Because transmission and reception are independent, you can build a port that advertises itself but ignores neighbors, or the reverse. Interface-level commands override the global default:

switch(config)# interface 1/1/1
switch(config-if)# lldp transmit        (advertise on this port)
switch(config-if)# no lldp receive      (ignore incoming LLDP frames)

The same commands work on the OOBM interface, which is enabled by default and frequently used to discover the management network:

switch(config)# interface mgmt
switch(config-if)# lldp transsmit

Tuning LLDP Timers and Traps

Global LLDP timers control how quickly neighbor information goes stale and how fast changes propagate. The default settings shown in show lldp configuration correspond to these global commands:

switch(config)# lldp timer 30          (LLDP transmit interval, 5-32768 s)
switch(config)# lldp holdtime 4        (hold time multiplier, 2-10)
switch(config)# lldp reinit 2          (reinitialization delay, 1-10 s)
switch(config)# lldp transmit-delay 2  (delay between advertisements, 1-8192 s)

SNMP traps for LLDP events must be enabled globally first; per-interface trap generation is on by default:

switch(config)# lldp trap enable

Verifying LLDP on ArubaOS-CX

switch# show lldp configuration
switch# show lldp configuration 1/1/1
switch# show lldp neighbors
switch# show lldp neighbors 1/1/1

show lldp configuration lists the global agent state and a per-port table of TX-ENABLED / RX-ENABLED flags, while show lldp neighbors reveals the remote device ID, port ID, and capabilities learned on each link - the fastest way to confirm which switch or IP phone is really on the other end of a cable.

LLDP-MED and Voice VLANs

ArubaOS-CX supports LLDP-MED so IP phones can advertise their power and network-policy needs; on converged ports this works together with the voice VLAN so the phone tags its traffic correctly. See our voice VLAN and IP phone configuration article for the access-port design that LLDP-MED complements.

Related reading: ArubaOS-CX VSX configuration guide, ArubaOS-CX VSF stacking, and LLDP vs CDP comparison.

原文链接：https://arubanetworking.hpe.com/techdocs/AOS-CX/10.13/HTML/fundamentals_8400/Content/Chp_Dev_disc/LLDP_cmds/lld-tra-10.htm