LLDP¶

LLDP (Link Layer Discovery Protocol, IEEE 802.1AB) lets neighboring devices tell each other who they are. The switch announces its name, its port and its management address on every port, and learns the same from the switches, routers, access points and phones connected to it. This answers "what is plugged into lan5?" without following the cable, and lets network management tools draw the topology.

LLDP is on by factory default, on all ports. The switch sends an LLDP frame on each port every 30 seconds, and neighbors keep its information for four times that (120 seconds). LLDP frames never leave the link they are sent on, so a neighbor is always directly connected.

What the switch announces:

Information	Value
Chassis ID	The switch's MAC address
Port ID and port description	The port's name, for example `lan5`
System name	The host name, unless a system name is configured
System description	The firmware name and version, for example `Ethernet Switch OS 1.0`, unless a description is configured. SNMP's `sysDescr` says the same.
Capabilities	Bridge, and router while the switch routes IP
Management address	The switch's IPv4 address on its routed VLAN interface, and an IPv6 address (usually the link-local one)

What neighbors learn

Every device on a port with LLDP learns the switch's name, firmware version and management address. Turn LLDP off on ports that face networks you do not trust, or leave out the management address (see below).

Settings¶

Setting	Default	Allowed
`enabled`	`true`	`false` turns LLDP off on all ports.
`hello-timer`	30	1 … 3600 seconds between two LLDP frames. Neighbors keep the information for four times this.
`system-name`	the host name	One line, up to 255 characters.
`system-description`	the firmware name and version	One line, up to 255 characters.
`suppress-tlv-advertisement`	none	`oc-lldp-types:MANAGEMENT_ADDRESS` leaves out the management address, `oc-lldp-types:SYSTEM_CAPABILITIES` the capabilities.
per port: `enabled`	`true`	`false` turns LLDP off on the port: the switch neither announces itself there nor learns the neighbor.

The switch checks these rules when you commit:

Rule	Error when broken
`hello-timer` is 1 … 3600	`lldp: hello-timer 0 is out of range 1..3600`
Only the management address and the capabilities can be left out: chassis ID, port ID and TTL are mandatory, and the switch always sends port description, system name and system description	`lldp: suppress-tlv-advertisement PORT_ID is not supported, only SYSTEM_CAPABILITIES and MANAGEMENT_ADDRESS`
A port setting names a switch port	`lldp: interfaces: interface vlan1 is not a configured switch port`
Name and description are one line	`lldp: system-name must be one line without control characters`

Status¶

For the switch:

Field	Meaning
`enabled`, `hello-timer`, `suppress-tlv-advertisement`	The settings in use
`system-name`, `system-description`	What the switch announces
`chassis-id`, `chassis-id-type`	The switch's chassis ID (`MAC_ADDRESS`)
`counters`	LLDP frames of all ports: `frame-in` received, `frame-out` sent, `frame-discard` received but invalid, `tlv-unknown` parts not understood, `entries-aged-out` neighbors forgotten because they stopped sending

Per port, enabled and the same counters (without entries-aged-out), and one entry per neighbor:

Field	Meaning
`id`	A number the switch gives the neighbor
`system-name`, `system-description`	The neighbor's name and description
`chassis-id`, `chassis-id-type`	The neighbor's identity, usually its MAC address (`MAC_ADDRESS`)
`port-id`, `port-id-type`, `port-description`	The neighbor's port the switch is connected to: its name (`INTERFACE_NAME`), MAC address (`MAC_ADDRESS`) or a local name (`LOCAL`)
`management-address`, `management-address-type`	Where the neighbor can be managed. Type `1` is IPv4, `2` IPv6. With several addresses, the first IPv4 address is shown.
`capabilities`	What the neighbor is (`MAC_BRIDGE`, `ROUTER`, `WLAN_ACCESS_POINT`, `TELEPHONE`, `STATION_ONLY`, …), each with `enabled` true if that function is active
`ttl`	How many seconds the neighbor asked to be remembered
`age`	Seconds since the neighbor's information last changed

A neighbor that stops sending is forgotten once its ttl has passed. A port can have more than one neighbor, for example behind an unmanaged switch.

Web UI¶

The LLDP card of the status page shows whether LLDP is on, the interval, and the system name and chassis ID the switch announces. Below, one row per port with whether LLDP is on there, and its neighbor: name (the description shows when you hover over it), the neighbor's port, chassis ID, management address and capabilities. A port with several neighbors has a row for each.

Edit on the card turns LLDP on or off, and sets the interval, the system name and description, and whether the management address and the capabilities are announced.
Edit on a port turns LLDP on or off for that port.

Remember Save configuration to keep the changes after a reboot.

CLI¶

Turn LLDP off and on¶

switch> set lldp config enabled false
switch> commit
switch> save

set lldp config enabled true, or delete lldp config enabled, turns it on again.

Turn LLDP off on one port¶

switch> set lldp interfaces interface lan8 config name lan8
switch> set lldp interfaces interface lan8 config enabled false
switch> commit
switch> save

Change the interval¶

switch> set lldp config hello-timer 10
switch> commit

Name and description¶

By default the switch announces its host name and its firmware. To announce something else:

switch> set lldp config system-name core-1
switch> set lldp config system-description "Rack 4, top"
switch> commit

delete lldp config system-name goes back to the host name.

Leave out the management address¶

switch> set lldp config suppress-tlv-advertisement oc-lldp-types:MANAGEMENT_ADDRESS
switch> commit

Neighbors¶

show lldp shows the settings, the counters, and the neighbors of each port:

switch> show lldp
openconfig-lldp:lldp {
   state {
      enabled true;
      hello-timer 30;
      system-name switch;
      system-description "Ethernet Switch OS 1.0";
      chassis-id 02:00:5e:10:00:01;
      chassis-id-type MAC_ADDRESS;
      ...
   }
   interfaces {
      ...
      interface lan8 {
         state {
            name lan8;
            enabled true;
            ...
         }
         neighbors {
            neighbor 1 {
               state {
                  system-name office-switch;
                  system-description "Example switch 2.1";
                  chassis-id c2:03:75:2a:2b:71;
                  chassis-id-type MAC_ADDRESS;
                  id 1;
                  age 3;
                  ttl 120;
                  port-id port3;
                  port-id-type INTERFACE_NAME;
                  port-description port3;
                  management-address 10.99.0.1;
                  management-address-type 1;
               }
               capabilities {
                  capability oc-lldp-types:MAC_BRIDGE {
                     state {
                        name oc-lldp-types:MAC_BRIDGE;
                        enabled true;
                     }
                  }
                  ...
               }
            }
         }
      }
   }
}

RESTCONF¶

LLDP is configured under:

/restconf/data/openconfig-lldp:lldp

RESTCONF spells identities out in full, for example openconfig-lldp-types:MANAGEMENT_ADDRESS.

Turn LLDP off:

curl -k -u ops -X PATCH -H 'Content-Type: application/yang-data+json' \
    -d '{"openconfig-lldp:config":{"enabled":false}}' \
    https://192.168.1.1/restconf/data/openconfig-lldp:lldp/config

Send every 10 seconds, with a name of its own, without the management address, and not on lan8 (/lldp may not exist yet, so the PATCH goes to the datastore):

curl -k -u ops -X PATCH -H 'Content-Type: application/yang-data+json' \
    -d '{"ietf-restconf:data":{"openconfig-lldp:lldp":{
          "config":{"hello-timer":10,"system-name":"core-1",
                    "suppress-tlv-advertisement":["openconfig-lldp-types:MANAGEMENT_ADDRESS"]},
          "interfaces":{"interface":[{"name":"lan8","config":{"name":"lan8","enabled":false}}]}}}}' \
    https://192.168.1.1/restconf/data

Back to the factory settings:

curl -k -u ops -X DELETE https://192.168.1.1/restconf/data/openconfig-lldp:lldp

The neighbors of lan5:

curl -k -u ops -H 'Accept: application/yang-data+json' \
    https://192.168.1.1/restconf/data/openconfig-lldp:lldp/interfaces/interface=lan5/neighbors

SNMP¶

While the SNMP agent is on, it also answers LLDP-MIB (IEEE 802.1AB): what the switch announces, and the neighbors of each port. LLDP-MIB lives below 1.0.8802.1.1.2, outside 1.3.6.1, so the SNMP view has to include 1.0.8802 (see Users, groups and views).

Not supported¶

Rejected when you commit:

setting the chassis ID (chassis-id, chassis-id-type): it is always the switch's MAC address
leaving out other parts than the management address and the capabilities

Not available at all: CDP, EDP, FDP and SONMP (the switch neither sends nor understands them), LLDP-MED (the extensions for IP phones), custom TLVs, setting the TTL other than through the interval, and LLDP traps.