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Difficulty: EasyLayer 2 Discovery Protocols (CDP and LLDP)

Network administrators use Layer 2 discovery protocols to discover adjacent network hardware and verify topology details. Match each Layer 2 discovery protocol attribute on the left with its corresponding protocol characteristic or default value on the right.

  • IEEE 802.1ABOpen vendor-neutral standard for Link Layer Discovery Protocol (LLDP)
  • Cisco Proprietary Discovery ProtocolCisco Discovery Protocol (CDP)
  • Default CDP Holdtime180 seconds
  • Default LLDP Holdtime120 seconds

Answer

IEEE 802.1AB matches Open vendor-neutral standard for Link Layer Discovery Protocol (LLDP); Cisco Proprietary Discovery Protocol matches Cisco Discovery Protocol (CDP); Default CDP Holdtime matches 180 seconds; Default LLDP Holdtime matches 120 seconds.
IEEE 802.1AB is the formal standard specification for LLDP. CDP is Cisco's proprietary discovery protocol. CDP defaults to an update timer of 60 seconds and a holdtime of 180 seconds, while LLDP defaults to a transmit timer of 30 seconds and a holdtime of 120 seconds.

Step-by-Step Solution

1
Identify the standard governing LLDP.
LLDP is defined under IEEE 802.1AB.
IEEE 802.1AB provides an open standard for neighbor discovery across multi-vendor equipment.
2
Identify the ownership model of CDP.
CDP is Cisco proprietary.
CDP was created by Cisco to allow Cisco switches, routers, and devices to discover each other.
3
Calculate or recall the default CDP holdtime.
The CDP holdtime defaults to 180 seconds.
CDP transmits messages every 60 seconds, and the default holdtime is set to 3 update intervals (180 seconds).
4
Calculate or recall the default LLDP holdtime.
The LLDP holdtime defaults to 120 seconds.
LLDP uses a default transmit timer of 30 seconds with a default holdtime multiplier of 4, producing a 120-second holdtime.

Key Concept

Distinguishing characteristics, standards, and default timers of CDP and LLDP.
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Topics

Layer 2 Discovery Protocols (CDP and LLDP)

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