Mandatory TLVs

When an LLDP agent transmits LLDP packets to other agents in the same 802 LAN segments, the following mandatory TLVs are always included:

Chassis ID

Port ID

Time to Live (TTL)

This section describes the above TLVs in detail.

Chassis ID

The Chassis ID identifies the device that sent the LLDP packets.

There are several ways in which a device may be identified. A chassis ID subtype, included in the TLV and shown in the following table, indicates how the device is being referenced in the Chassis ID field.

Chassis ID subtypes

ID subtype	Description
0	Reserved
1	Chassis component
2	Interface alias
3	Port component
4	MAC address
5	Network address
6	Interface name
7	Locally assigned
8 - 255	Reserved

RUCKUS devices use chassis ID subtype 4, the base MAC address of the device. Other third party devices may use a chassis ID subtype other than 4. The chassis ID will appear similar to the following on the remote device, and in the CLI display output on the RUCKUS device (show lldp local-info ).

Chassis ID (MAC address):  0000.0033.e2c0

The chassis ID TLV is always the first TLV in the LLDPDU.

Port ID

The Port ID identifies the port from which LLDP packets were sent.

There are several ways in which a port may be identified, as shown in the following table. A port ID subtype, included in the TLV, indicates how the port is being referenced in the Port ID field.

Port ID subtypes

ID subtype	Description
0	Reserved
1	Interface alias
2	Port component
3	MAC address
4	Network address
5	Interface name
6	Agent circuit ID
7	Locally assigned
8 - 255	Reserved

RUCKUS devices use port ID subtype 3, the permanent MAC address associated with the port. Other third party devices may use a port ID subtype other than 3. The port ID appears similar to the following on the remote device, and in the CLI display output on the RUCKUS device (show lldp local-info).

Port ID (MAC address):  0000.0033.e2d3

The LLDPDU format is shown in LLDP packets.

The Port ID TLV format is shown below.

Port ID TLV packet format

TTL value

The Time to Live (TTL) Value is the length of time the receiving device should maintain the information acquired by LLDP in its MIB.

The TTL value is automatically computed based on the LLDP configuration settings. The TTL value will appear similar to the following on the remote device, and in the CLI display output on the RUCKUS device (show lldp local-info).

Time to live: 40 seconds

If the TTL field has a value other than zero, the receiving LLDP agent is notified to completely replace all information associated with the LLDP agent/port with the information in the received LLDPDU.

If the TTL field value is zero, the receiving LLDP agent is notified that all system information associated with the LLDP agent/port is to be deleted. This TLV may be used, for example, to signal that the sending port has initiated a port shutdown procedure.