3Com 2928 - Baseline Plus Switch PWR, Руководство пользователя

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Type Description
Manufacturer Name Allows a MED endpoint to advertise its vendor name.
Model Name Allows a MED endpoint to advertise its model name.
Asset ID
Allows a MED endpoint to advertise its asset ID. The typical case is
that the user specifies the asset ID for the endpoint to facilitate
directory management and asset tracking.
Location Identification
Allows a network device to advertise the appropriate location identifier
information for an endpoint to use in the context of location-based
applications.
See the IEEE standard (LLDP) 802.1AB-2005 and the LLDP-MED standard (ANSI/TIA-1057) for more
information about LLDPDU TLVs.
Management address
The management address of a device is used by the network management system to identify and
manage the device for topology maintenance and network management. The management address is
encapsulated in the management address TLV.
Operating Modes of LLDP
LLDP can operate in one of the following modes:
z
TxRx mode. A port in this mode sends and receives LLDPDUs.
z
Tx mode. A port in this mode only sends LLDPDUs.
z
Rx mode. A port in this mode only receives LLDPDUs.
z
Disable mode. A port in this mode does not send or receive LLDPDUs.
Each time the LLDP operating mode of a port changes, its LLDP protocol state machine re-initializes. To
prevent LLDP from being initialized too frequently at times of frequent operating mode change, an
initialization delay, which is user configurable, is introduced. With this delay mechanism, a port must
wait for the specified interval before it can initialize LLDP after the LLDP operating mode changes.
How LLDP Works
Transmitting LLDPDUs
An LLDP-enabled port operating in TxRx mode or Tx mode sends LLDPDUs to its directly connected
devices both periodically and when the local configuration changes. To prevent the network from being
overwhelmed by LLDPDUs at times of frequent local device information change, an interval is
introduced between two successive LLDPDUs.
This interval is shortened to 1 second in either of the following two cases:
z
A new neighbor is discovered, that is, a new LLDPDU is received carrying device information new
to the local device.
z
The LLDP operating mode of the port changes from Disable/Rx to TxRx or Tx.