Information About LLDP
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LLDP
The Cisco Discovery Protocol (CDP) is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured devices (routers, bridges, access servers, switches, and controllers). CDP allows network management applications to automatically discover and learn about other Cisco devices connected to the network.
To support non-Cisco devices and to allow for interoperability between other devices, the device supports the IEEE 802.1AB Link Layer Discovery Protocol (LLDP). LLDP is a neighbor discovery protocol that is used for network devices to advertise information about themselves to other devices on the network. This protocol runs over the data-link layer, which allows two systems running different network layer protocols to learn about each other.
LLDP Supported TLVs
LLDP supports a set of attributes that it uses to discover neighbor devices. These attributes contain type, length, and value descriptions and are referred to as TLVs. LLDP supported devices can use TLVs to receive and send information to their neighbors. This protocol can advertise details such as configuration information, device capabilities, and device identity.
The switch supports these basic management TLVs. These are mandatory LLDP TLVs.
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Port description TLV
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System name TLV
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System description TLV
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System capabilities TLV
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Management address TLV
These organizationally specific LLDP TLVs are also advertised to support LLDP-MED.
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Port VLAN ID TLV (IEEE 802.1 organizationally specific TLVs)
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MAC/PHY configuration/status TLV (IEEE 802.3 organizationally specific TLVs)
LLDP TLVs are used by Common Industrial Protocol, (CIP) in industrial automation applications. The switch supports the following CIP Identification TLVs:
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Vendor Id
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Product Type
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Product Code
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Product Major Revision
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Product Minor Revision
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Product CIP Serial Number
For information about CIP, see CIP and MODBUS Configuration Guide, Cisco Catalyst IE3x00 Rugged, IE3400 Heavy Duty, and ESS3300 Series Switches.
The show lldp neighbors detail tlv-dump command displays LLDP TLVs. See Monitoring and Maintaining LLDP for more information about show lldp commands.
Default LLDP Configuration
Feature |
Default Setting |
---|---|
LLDP global state |
Enabled |
LLDP holdtime (before discarding) |
120 seconds |
LLDP timer (packet update frequency) |
30 seconds |
LLDP reinitialization delay |
2 seconds |
LLDP tlv-select |
Enabled to send and receive all TLVs |
LLDP interface state |
Enabled |
LLDP receive |
Enabled |
LLDP transmit |
Enabled |