LLDP

The interval between the LLDP messages of a normal transmission period is configurable from 1 to 3600 seconds and defaults to 30 seconds. It also determines the Time To Live of the transmitted messages, which is the interval multiplied by the hold multiplier of 4. A shortened interval takes effect at once, without waiting out the transmission that is already scheduled.

IPATCH request message:

The global configuration is retrieved as shown below.

FETCH request message:

FETCH response message:

Rx and Tx of LLDP messages can be enabled per port, using DMAC 01-80-C2-00-00-0E.

IPATCH request message:

The configuration of the first port is retrieved as shown below.

FETCH request message:

FETCH response message:

An Organizationally Specific TLV carries information defined by an organization rather than by IEEE 802.1AB, identified by the Organizationally Unique Identifier (OUI) of that organization and by a subtype it chooses. Each port has a list of these, keyed by OUI and subtype, and one TLV is transmitted for each entry in every LLDPDU sent on the port. An entry is transmitted by virtue of existing, so transmission is stopped by deleting the entry.

The number of entries a port takes, and the maximum size of the information field of each, are declared by the board configuration using lldp_custom_tlv_count (default 1) and lldp_custom_tlv_size (default 8).

The first port is set up to transmit a TLV with OUI 0x010203, subtype 0x04 and the two information octets 0x05 and 0x06 as shown below. The OUI is a 24 bit number, so 0x010203 is written as 66051, and the information field is a binary leaf, so it is written in base64, where 0x0506 is 'BQY='.

IPATCH request message:

The TLV is retrieved by its keys as shown below. Leaving the keys out of the request would retrieve every custom TLV of the port instead.

FETCH request message:

FETCH response message:

Remote data received on the port is retrieved as shown below.

FETCH request message:

FETCH response message:

When Tx is enabled on a port, LLDP messages including the TLVs listed above are sent every 30 seconds. If the IP address is changed, a number of transmissions are done every second.

LLDP counters for a port are retrieved as shown below.

FETCH response message:

Frame preemption is negotiated via LLDP organizationally specific TLVs. The negotiation is done for each data direction on the switch port:

Frame preemption may be enabled per Tx queue on a port. By default, all queues are set up for express operation, disabling frame preemption. A number of queues, starting with queue 0 (low priority) may be set up as preemptable.

The first queue on the port is set up as preemptable as shown below.

IPATCH request message:

The frame preemption configuration is retrieved as shown below.

FETCH request message:

FETCH response message: