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 (between 1 and 10 seconds) 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
Set LLDP Mode
By default, the lldpd service sends LLDP frames unless it detects a CDP peer, then it sends CDP frames. You can change this behavior and configure the lldpd service to send only CDP frames or only LLDP frames.
- You configure the
lldpdservice to send only CDP or only LLDP frames globally for all interfaces; you cannot configure these settings for specific interfaces. - If you configure the
lldpdservice to send only CDP frames (CDPv1 or CDPv2), LLDP DCBX TLV transmission for QOS ROCE is not supported.
To send only CDPv1 frames:
cumulus@switch:~$ nv set service lldp mode force-send-cdpv1
cumulus@switch:~$ nv config apply
To send only CDPv2 frames:
cumulus@switch:~$ nv set service lldp mode force-send-cdpv2
cumulus@switch:~$ nv config apply
To send only LLDP frames:
cumulus@switch:~$ nv set service lldp mode force-send-lldp
cumulus@switch:~$ nv config apply
To reset to the default setting (to send both CDP and LLDP frames):
cumulus@switch:~$ nv set service lldp mode default
cumulus@switch:~$ nv config apply
Edit the /etc/default/lldpd file and add one of the following options to the DAEMON_ARGS section:
To send only CDPv1 frames:
cumulus@switch:~$ sudo nano /etc/default/lldpd
...
DAEMON_ARGS="-cc -ll -M 4"
To send only CDPv2 frames:
cumulus@switch:~$ sudo nano /etc/default/lldpd
...
DAEMON_ARGS="-cccc -ll -M 4"
To send only LLDP frames:
cumulus@switch:~$ sudo nano /etc/default/lldpd
...
DAEMON_ARGS="-l -M 4"
To reset to the default setting (to send both CDP and LLDP frames):
cumulus@switch:~$ sudo nano /etc/default/lldpd
...
DAEMON_ARGS="-c -M 4"
You must restart the lldpd service for the changes to take effect.
cumulus@switch:~$ sudo systemctl restart lldpd
To show the current LLDP mode, run the nv show service lldp command. The following example shows that the lldpd service sends CDPv2 frames only.
cumulus@leaf02:mgmt:~$ nv show service lldp
operational applied
------------------ ---------------- ----------------
dot1-tlv off off
mode force-send-cdpv2 force-send-cdpv2
tx-hold-multiplier 4 4
tx-interval 30 30
LLDP DCBX TLVs
DCBX is an extension of LLDP. Cumulus Linux supports DCBX TLVs to provide additional information in LLDP packets to peers, such as VLAN information and QoS. Adding QoS configuration as part of the DCBX TLVs allows automated configuration on hosts and switches that connect to the switch.
- Cumulus Linux can send a maximum of 250 VLANS per switch port in one LLDP frame.
- Cumulus Linux does not support CEE DCBX TLVs.
- Cumulus Linux limits DCBX support to enabling DCBX TLVs (either with ROCE global configuration or per interface) as documented in the IEEE 802.1Q standard.
Cumulus Linux supports the following TLVs:
IEEE 802.1 TLVs
| Name | Subtype | Description |
|---|---|---|
| Port VLAN ID | 1 | The port VLAN identifier. |
| VLAN Name | 3 | The name of any VLAN to which the port belongs. |
| Link Aggregation | 7 | Indicates if the port supports link aggregation and if it is on. |
QoS TLVs
| Name | Subtype | Description |
|---|---|---|
| ETS Configuration | 9 | The ETS configuration settings on the switch. |
| ETS Recommendation | A | The recommended ETS settings that the switch wants the connected peer interface to use. |
| PFC Configuration | B | The PFC configuration settings on the switch. |
IEEE 802.3 TLVs
Cumulus Linux transmits the following 802.3 TLVs by default. You do not need to enable them.
| Name | Subtype | Description |
|---|---|---|
| Link Aggregation | 3 | Indicates if the port supports link aggregation and if it is on. |
| Maximum Frame Size | 4 | The MTU configuration on the port. The MTU on the port is the MFS. |
Transmit IEEE 802.1 TLVs
You can transmit the 802.1 TLV types (VLAN name, Port VLAN ID, and IEEE 802.1 Link Aggregation) when exchanging LLDP messages. By default, 802.1 TLV transmission is off and the switch sends all LLDP frames without 802.1 TLVs.
To enable 802.1 TLV transmission, run the nv set service lldp dot1-tlv on command:
cumulus@switch:~$ nv set service lldp dot1-tlv on
cumulus@switch:~$ nv config apply
Transmit QoS TLVs
You can enable QoS TLV transmission (ETS Configuration, ETS Recommendation, PFC Configuration) on an interface. By default, all QoS TLV transmission is off on all interfaces.
Adding the QoS TLVs to LLDP packets on an interface relies on PFC and ETS configuration from switchd. Refer to Quality of Service for information on configuring PFC and ETS.
When you enable ROCE on the switch:
- QoS TLV transmission (PFC Configuration, ETS Configuration, and ETS Recommendation) is on globally for all ports, which overrides any QoS TLV transmission setting on a switch port interface.
- LLDP frames for all switch port interfaces carry PFC configuration, ETS configuration, ETS recommendation, and APP Priority TLVs. The ETS configuration and PFC configuration TLV payloads are the same for all interfaces.
To enable PFC Configuration TLV transmission, run the nv set interface <interface> lldp dcbx-pfc-tlv on command:
cumulus@switch:~$ nv set interface swp1 lldp dcbx-pfc-tlv on
cumulus@switch:~$ nv config apply
To enable ETS Configuration TLV transmission, run the nv set interface <interface> lldp dcbx-ets-config-tlv on command:
cumulus@switch:~$ nv set interface swp1 lldp dcbx-ets-config-tlv on
cumulus@switch:~$ nv config apply
To enable ETS Recommendation TLV transmission, run the nv set interface <interface> lldp dcbx-ets-recomm-tlv on command:
cumulus@switch:~$ nv set interface swp1 lldp dcbx-ets-recomm-tlv on
cumulus@switch:~$ nv config apply
The interface must be a physical interface; you cannot enable TLVs on bonds.
Show DCBX TLV Settings
To show if IEEE 802.1 TLV transmission is on, run the NVUE nv show service lldp command:
cumulus@leaf01:mgmt:~$ nv show service lldp
operational applied description
------------------ ----------- ------- ----------------------------------------------------------------------
dot1-tlv on on Enable dot1 TLV advertisements on enabled ports
tx-hold-multiplier 4 4 < TTL of transmitted packets is calculated by multiplying the tx-in...
tx-interval 30 30 change transmit delay
To show if Qos TLV transmission is on for an interface, run the NVUE nv show interface <interface> command:
cumulus@leaf01:mgmt:~$ nv show interface swp1
operational applied description
------------------------ ----------------- ----------- ---------------------------------------------------
...
lldp
dcbx-ets-config-tlv on DCBX ETS config TLV flag
dcbx-ets-recomm-tlv off DCBX ETS recommendation TLV flag
dcbx-pfc-tlv on DCBX PFC TLV flag
...
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
- Cumulus Linux does not support LLDP Annex E (and Annex D).
- 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.