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Link Layer Discovery Protocol (LLDP)

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Esti Lederer edited this page Aug 25, 2021 · 36 revisions

This section describes how to configure Link Layer Discovery Protocol (LLDP) on the device, using one of the following methods:

Open-LLDP

This section describes how to configure LLDP protocol using an Open-LLDP agent.

Default Behavior

By default, the LLDP agent does not enable LLDP protocol on switchDev interfaces on the system. This configuration should be done manually (e.g. enable protocol, configure TLVs etc). After restarting the agent, the configuration is preserved, the LLDP agent configuration is stored automatically in /var/lib/lldpad/lldpad.conf file.

Agent Configuration

  • To enable LLDP (receive & transmit TLV information) on a specific port, use the following command:
    ip link set dev <SW-PORT> up
    lldptool -L -i <SW-PORT> adminStatus=rxtx

  • To get the status of a TLV (enabled/disable):
    lldptool -t -i <SW-PORT> -V <TLV-NAME> -c enableTx

  • To enable transmitting a specific TLV value:
    lldptool -T -I <SW-PORT> -V <TLV-NAME> enableTx=yes

  • To get local the value of all enabled TLVs:
    lldptool -t -i <SW-PORT>

  • To query LLDP statistics on a specific port:
    lldptool -S -i <SW-PORT>

  • To query TLV information from the switch about a connected neighbor:
    lldptool -t -n -i <SW-PORT>

  • To get a specific TLV value:
    lldptool -t -n -V portID -i <SW-PORT>

Configure Mandatory TLV

Once the LLDP protocol is enabled on a switchDev port, the mandatory TLV information is enabled automatically. The mandatory TLV cannot be disabled by user.

Configure Optional TLV

The following table describes the TLV names (including mandatory) that can be used by the agent to configure required TLV values:

TLV Name TLV Descripton
chassisID Chassis ID TLV
portID Port ID TLV
TTL Time to Live TLV
portDesc Port Description TLV
sysName System Name TLV 
sysDesc System Description TLV
sysCap System Capabilities TLV
mngAddr Management Address TLV
macPhyCfg MAC/PHY Configuration Status TLV
linkAgg Link Aggregation TLV
MTU Maximum Frame Size TLV

NOTE: The agent does not work on a physical port if it belongs to a LAG.

LLDPd

This section describes how to configure the LLDP protocol using an LLDPd agent.

Default Behavior

By default, the LLDP agent enables LLDP protocol on all available physical interfaces. To limit the agent to listen only on switchDev interfaces, you need to provide a configuration file.

Agent Configuration

  • To limit the LLDP agent to specific port(s):
    lldpcli configure system interface pattern sw*

  • To enable/disable LLDP on a specific interface:
    lldpcli configure ports sw1p1 lldp status rx-and-tx

  • To query LLDP statistics on port:
    lldpcli show statistics ports sw1p1

  • To query TLV information from switch about connected neighbor:
    lldpcli show neighbors

NOTE: Detailed instructions how to configure the agent can be found on lldpd manual page at https://vincentbernat.github.io/lldpd/usage.html.

Configure Mandatory/Optional TLV

The mandatory and optional TLV information is enabled automatically by the agent and cannot be disabled or enabled separately.

IEEE 802.1/ IEEE 802.3 Organizationally Specific TLV

This information is not supported by the agent. However, TLV information can be provided statically via custom TLV configuration manually. For example:

  • IEEE 802.1
    lldpcli configure lldp custom-tlv oui 00,80,c2 subtype 1 oui-info 56,78,9,0,90,78,54
  • IEEE 802.3
    `lldpcli configure lldp custom-tlv oui 00,12,0f subtype 1 oui-info 56,78,9,0,90,78,54

TLV Information Values

The following table describes TLV values that LLDPd will advertise in case of default configuration.
The table shows the mandatory TLV information.

TLV name Value description
End of LLDPDU End of TLV information
Chassis ID TLV Mac address of management interface
Port ID TLV Switchdev port MAC address
Time to Live TLV TTL
Optional TLVs information
Port Description TLV Switchdev port name
System Name TLV Hostname (hostname tool)
System Description TLV OS system description in format: <OS release name> <kernel name> <kernel release> <kernel version> <machine hardware name>. Can be obtained via Linux tools like: sed -ne 's/PRETTY_NAME="\(.*\)"/\1/p' /etc/os-release; uname -s; uname -r; uname -v; uname -m
System Capabilities TLV System capabilities such as: bridge, router
Management Address TLV IP of management interface

NOTE: Advertising IEEE 802.1/ IEEE 802.3 Organizationally Specific TLVs is not supported by the agent. This type of advertising can only be done via static custom TLVs.

NOTES

  • LLDP is supported on physical interfaces only, does not matter if port is part of bridge or lag.
  • LLDPd does not support advertising of IEEE 802.3/802.1 TLV information automatically. To advertise the information (static only), apply manual LLDPd custom TLV configuration.

Network Configurations

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