CCNA 2.8.b: Link Layer Discovery Protocol (LLDP)


Link Layer Discovery Protocol LLDP is similar to CDP in that it supports non-Cisco devices


Study Notes:

Link Layer Discovery Protocol (LLDP):

  • Link Layer Discovery Protocol (LLDP) is a device discovery protocol that runs over Layer 2 (the data link layer) on many devices (routers, bridges, access servers, and switches)
  • LLDP allows network management applications to automatically discover and learn about other LLDP enabled devices on the network
  • IEEE 802.1AB LLDP protocol is used to allow for interoperability between non-Cisco devices
  • 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 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
  • Details such as configuration information, device capabilities, and device identity can be advertised using this protocol
  • The switch supports the following basic management TLVs, which are optional:
    • Port description TLV
    • System name TLV
    • System description TLV
    • System capabilities TLV
    • Management address TLV
  • These organizationally specific LLDP TLVs are also advertised to support LLDP-MED
    • Port VLAN ID TLV ((IEEE 802.1 organizationally specific TLVs)
    • MAC/PHY configuration/status TLV(IEEE 802.3 organizationally specific TLVs)
  • Optional LLDP settings include
    • holdtime - amount of time receiving device holds my info before discarding (default 120)
    • reinit - delay time in seconds for LLDP to initialize on any interface (default 2)
    • timer - transmission frequency of LLDP updates in seconds (default 30)
    • tlv-select - specifies the LLDP TLVs to send or receive
    • med-tlv-select - specifies the LLDP-MED TLVs to send or receive


PacketTracer Lab: CCNA-2.8.b-How-to-configure-Link-Layer-Discovery-Protocol-LLDP.pkt

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