Hirschmann GREYHOUND GRS1020, Справочное руководство

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Operation diagnosis
13.9 Topology discovery
207
UM Config GRS
Release 8.0 09/2019
13.9 Topology discovery
IEEE 802.1AB defines the Link Layer Discovery Protocol (LLDP). LLDP lets the user automatically
detect the LAN network topology.
Devices with LLDP active:

broadcast their connection and management information to neighboring devices on the shared
LAN. When the receiving device has its LLDP function active, evaluation of the devices occur.

receive connection and management information from neighbor devices on the shared LAN,
provided these adjacent devices also have LLDP active.

build a management information database and object definitions for storing information about
adjacent devices with LLDP active.
As the main element, the connection information contains an exact, unique identifier for the
connection end point: MAC (Service Access Point). This is made up of a device identifier which is
unique on the entire network and a unique port identifier for this device.

Chassis identifier (its MAC address)

Port identifier (its port-MAC address)

Description of port

System name

System description

Supported system capabilities

System capabilities currently active

Interface ID of the management address

VLAN-ID of the port

Auto-negotiation status on the port

Medium, half/full duplex setting and port speed setting

Information about the VLANs installed in the device (VLAN-ID and VLAN name, irrespective of
whether the port is a VLAN participant).
A network management station can call up this information from devices with activated LLDP. This
information enables the network management station to map the topology of the network.
Non-LLDP devices normally block the special Multicast LLDP IEEE MAC address used for
information exchange. Non-LLDP devices therefore discard LLDP packets. If you position a non-
LLDP capable device between 2 LLDP capable devices, then the non-LLDP capable device
prohibits information exchanges between the 2 LLDP capable devices.
The Management Information Base (MIB) for a device with LLDP capability holds the LLDP
information in the lldp MIB and in the private HM2-LLDP-EXT-HM-MIB and HM2-LLDP-MIB.
13.9.1 Displaying the Topology discovery results
To show the topology of the network:
When you use a port to connect several devices, for example via a hub, the table contains a line
for each connected device.
Activating Display FDB Entries at the bottom of the table lets you display devices without active
LLDP support in the table. In this case, the device also includes information from its FDB
(forwarding database).

Open the
Diagnostics > LLDP > Topology Discovery
dialog,
LLDP
tab.