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VS-2400S 24 Ports VDSL2 Managed IP DSLAM with POTS splitter USER
’S MANUAL Ver.A3
92
Sending LLDP PDUs
A LLDP-enabled device operating in the TxRx mode or Tx mode sends LLDP PDUs to its directly connected devices periodically.
It also sends LLDP PDUs when the local configuration changes to inform the neighboring devices of the change timely. In any of
the two cases, an interval exists between two successive operations of sending LLDP PDUs. This prevents the network from being
overwhelmed by LLDP PDUs even if the LLDP operating mode changes frequently.
To enable the neighboring devices to be informed of the existence of a device or an LLDP operating mode change (from the
disable mode to TxRx mode, or from the Rx mode to Tx mode) timely, a device can invoke the fast sending mechanism. In this
case, the interval to send LLDP PDUs changes to one second. After the device sends specific number of LLDP PDUs, the interval
restores to the normal. (A neighbor is discovered when a device receives an LLDPDU and no information about the sender is
locally available.)
Receiving LLDP PDUs
An LLDP-enabled device operating in the TxRx mode or Rx mode validates the TLVs carried in the LLDP PDUs which receive
and store the valid neighboring information. An LLDP PDU also carries a TTL (time to live) setting with it. The information about
a neighboring device maintained locally ages out when the corresponding TTL expires.
The TTL of the information about a neighboring device is determined by the following expression:
TTL = LLDP hold time × LLDP PDU sending interval (hello-time)
You can set the TTL by configuring the LLDP hold-time and hello-time. Note that the TTL can be up to 65535 seconds. TTL
longer than it will be rounded off to 65535 seconds.