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3.3.2. Link Layer Discovery Protocol (LLDP)
LLDP (IEEE 802.1AB) is the vendor-neutral alternative to CDP.
Switch(config)# lldp run ! Enable globally
Switch# show lldp neighbors
Comparison:
| Feature | CDP | LLDP |
|---|---|---|
| Standard | Cisco proprietary | IEEE 802.1AB |
| Default state | Enabled | Disabled |
| Timer | 60 seconds | 30 seconds |
| Holdtime | 180 seconds | 120 seconds |
| Message format | TLVs; the holdtime tells neighbors how long to cache the entry | TLVs; a mandatory TTL TLV does the same |
⚠️ Exam Trap: CDP is a security risk in some environments because it reveals device information. Disable it on ports facing untrusted networks.
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Written byAlvin Varughese
Founder•20 professional certifications