Link Layer Discovery Protocol
LLDP shows information about connected devices.
The lldpd daemon implements the IEEE802.1AB LLDP standard and starts at system boot. All lldpd command line arguments are in the /etc/default/lldpd file.
lldpd supports CDP (Cisco Discovery Protocol, v1 and v2) and logs by default into /var/log/daemon.log with an lldpd prefix.
Configure LLDP Timers
You can configure the frequency of LLDP updates (between 10 and 300 seconds) and the amount of time to hold the information before discarding it. The hold time interval is a multiple of the tx-interval.
The following example commands configure the frequency of LLDP updates to 100 and the hold time to 3.
cumulus@switch:~$ nv set service lldp tx-interval 100
cumulus@switch:~$ nv set service lldp tx-hold-multiplier 3
cumulus@switch:~$ nv config apply
Create the /etc/lldpd.conf file or create a file in the /etc/lldpd.d/ directory with a .conf suffix and add the timers:
cumulus@switch:~$ sudo nano /etc/lldpd.conf
configure lldp tx-interval 40
configure lldp tx-hold 3
...
Restart the lldpd service for the changes to take effect:
cumulus@switch:~$ sudo systemctl restart lldpd
Disable LLDP on an Interface
To disable LLDP on a single interface, edit the /etc/default/lldpd file. This file specifies the default options to present to the lldpd service when it starts. The following example uses the -I option to disable LLDP on swp43:
cumulus@switch:~$ sudo nano /etc/default/lldpd
# Add "-x" to DAEMON_ARGS to start SNMP subagent
# Enable CDP by default
DAEMON_ARGS="-c -I *,!swp43"
Restart the lldpd service for the changes to take effect:
cumulus@switch:~$ sudo systemctl restart lldpd
Enable the SNMP Subagent
LLDP does not enable the SNMP subagent by default. To enable the SNMP subagent, edit the /etc/default/lldpd file and add the -x option:
cumulus@switch:~$ sudo nano /etc/default/lldpd
# Add "-x" to DAEMON_ARGS to start SNMP subagent
# Enable CDP by default
DAEMON_ARGS="-c -x -M 4"
Restart the lldpd service for the changes to take effect:
cumulus@switch:~$ sudo systemctl restart lldpd
- The
-coption enables backwards compatibility with CDP. See Change CDP Settings below. - The
-M 4option sends a field in discovery packets to indicate that the switch is a network device.
Change CDP Settings
Cumulus Linux provides support for CDP so that the switch can advertise information about itself with Cisco routers that do not support LLDP. By default, the Cumulus Linux switch sends CDP packets only if the peer sends CDP packets. You can change this setting by replacing -c in the /etc/default/lldpd file with one of the following options:
| Option | Description |
|---|---|
| -cc | The Cumulus Linux switch sends CDPv1 packets even when there is no detected CDP peer. |
| -ccc | The Cumulus Linux switch sends CDPv2 packets even when there is no detected CDP peer. |
| -cccc | The Cumulus Linux switch disables CDPv1 and enables CDPv2. |
| -ccccc | The Cumulus Linux switch disables CDPv1 and forces CDPv2. |
The following example changes the CDP setting to -ccc so that the switch sends CDPv2 packets even when there is no detected CDP peer:
cumulus@switch:~$ sudo nano /etc/default/lldpd
...
# Enable CDP by default
DAEMON_ARGS="-ccc -x -M 4"
You must restart the lldpd service for the changes to take effect.
cumulus@switch:~$ sudo systemctl restart lldpd
Troubleshooting
You can use the lldpcli tool to query the lldpd daemon for neighbors, statistics, and other running configuration information. See man lldpcli(8) for details.
To show all neighbors on all ports and interfaces:
cumulus@switch:~$ sudo lldpcli show neighbors
-------------------------------------------------------------------------------
LLDP neighbors:
-------------------------------------------------------------------------------
Interface: eth0, via: LLDP, RID: 1, Time: 0 day, 17:38:08
Chassis:
ChassisID: mac 08:9e:01:e9:66:5a
SysName: PIONEERMS22
SysDescr: Cumulus Linux version 4.1.0 running on quanta lb9
MgmtIP: 192.168.0.22
Capability: Bridge, on
Capability: Router, on
Port:
PortID: ifname swp47
PortDescr: swp47
-------------------------------------------------------------------------------
Interface: swp1, via: LLDP, RID: 10, Time: 0 day, 17:08:27
Chassis:
ChassisID: mac 00:01:00:00:09:00
SysName: MSP-1
SysDescr: Cumulus Linux version 4.1.0 running on QEMU Standard PC (i440FX + PIIX, 1996)
MgmtIP: 192.0.2.9
MgmtIP: fe80::201:ff:fe00:900
Capability: Bridge, off
Capability: Router, on
Port:
PortID: ifname swp1
PortDescr: swp1
-------------------------------------------------------------------------------
Interface: swp2, via: LLDP, RID: 10, Time: 0 day, 17:08:27
Chassis:
ChassisID: mac 00:01:00:00:09:00
SysName: MSP-1
SysDescr: Cumulus Linux version 4.1.0 running on QEMU Standard PC (i440FX + PIIX, 1996)
MgmtIP: 192.0.2.9
MgmtIP: fe80::201:ff:fe00:900
Capability: Bridge, off
Capability: Router, on
Port:
PortID: ifname swp2
PortDescr: swp2
-------------------------------------------------------------------------------
Interface: swp3, via: LLDP, RID: 11, Time: 0 day, 17:08:27
Chassis:
ChassisID: mac 00:01:00:00:0a:00
SysName: MSP-2
SysDescr: Cumulus Linux version 4.1.0 running on QEMU Standard PC (i440FX + PIIX, 1996)
MgmtIP: 192.0.2.10
MgmtIP: fe80::201:ff:fe00:a00
Capability: Bridge, off
Capability: Router, on
Port:
PortID: ifname swp1
PortDescr: swp1
...
To show lldpd statistics for all ports:
cumulus@switch:~$ sudo lldpcli show statistics
----------------------------------------------------------------------
LLDP statistics:
----------------------------------------------------------------------
Interface: eth0
Transmitted: 9423
Received: 17634
Discarded: 0
Unrecognized: 0
Ageout: 10
Inserted: 20
Deleted: 10
--------------------------------------------------------------------
Interface: swp1
Transmitted: 9423
Received: 6264
Discarded: 0
Unrecognized: 0
Ageout: 0
Inserted: 2
Deleted: 0
---------------------------------------------------------------------
Interface: swp2
Transmitted: 9423
Received: 6264
Discarded: 0
Unrecognized: 0
Ageout: 0
Inserted: 2
Deleted: 0
---------------------------------------------------------------------
Interface: swp3
Transmitted: 9423
Received: 6265
Discarded: 0
Unrecognized: 0
Ageout: 0
Inserted: 2
Deleted: 0
----------------------------------------------------------------------
...
To show a summary of lldpd statistics for all ports:
cumulus@switch:~$ sudo lldpcli show statistics summary
---------------------------------------------------------------------
LLDP Global statistics:
---------------------------------------------------------------------
Summary of stats:
Transmitted: 648186
Received: 437557
Discarded: 0
Unrecognized: 0
Ageout: 10
Inserted: 38
Deleted: 10
To show the running LLDP configuration:
cumulus@switch:~$ sudo lldpcli show running-configuration
--------------------------------------------------------------------
Global configuration:
--------------------------------------------------------------------
Configuration:
Transmit delay: 30
Transmit hold: 4
Receive mode: no
Pattern for management addresses: (none)
Interface pattern: (none)
Interface pattern blacklist: (none)
Interface pattern for chassis ID: (none)
Override description with: (none)
Override platform with: Linux
Override system name with: (none)
Advertise version: yes
Update interface descriptions: no
Promiscuous mode on managed interfaces: no
Disable LLDP-MED inventory: yes
LLDP-MED fast start mechanism: yes
LLDP-MED fast start interval: 1
Source MAC for LLDP frames on bond slaves: local
Portid TLV Subtype for lldp frames: ifname
--------------------------------------------------------------------
Considerations
- Annex E (and hence Annex D) of IEEE802.1AB (lldp) is not supported.
- If you configure both an eth0 IP address and a loopback IP address on the switch, LLDP advertises the loopback IP address as the management IP address. In this case, the Cumulus Linux switch behaves more like a typical Linux host than a networking appliance.