LLDP and CDP are both network discovery protocols, but they have some key differences:

1. Standardization and Vendor-Neutrality:
  • LLDP is an IEEE standard (802.1AB) and is an open standard, meaning it is publicly accessible and can be implemented by any vendor. This makes LLDP highly versatile and suitable for multi-vendor environments.
  • CDP is a proprietary protocol developed by Cisco. It is primarily used in Cisco environments and may not be compatible with devices from other vendors.
2. Information Exchanged:
Both protocols exchange similar types of information, such as device identifiers, port identifiers, capabilities, and network policies. However, CDP may provide more detailed information specific to Cisco devices.
3. Configuration and Management:
  • LLDP can be easier to manage in diverse network environments due to its standardization.
  • CDP might offer more advanced features and integration within Cisco environments, but requires Cisco network infrastructure.
4. Security Aspects:
  • LLDP is considered more flexible in terms of security, as it can be used across various devices.
  • CDP can reveal detailed network infrastructure information, which could be a security risk if not properly managed.
5. Use Cases:
  • LLDP is often used in mixed environments where devices from different vendors need to communicate discovery information.
  • CDP is ideal for Cisco-centric networks for detailed management of Cisco devices.
6. Interoperability:
  • LLDP has a higher degree of interoperability due to its status as an open standard.
  • CDP may have limited interoperability with non-Cisco devices.

In summary, LLDP, as an open standard, is suitable for diverse network environments, while CDP, being proprietary, offers Cisco-specific advantages but may lack the versatility of LLDP in multi-vendor environments.

I want to note that LLDP is not open source. LLDP (Link Layer Discovery Protocol) is an “open standard”. Open standards, like LLDP, are developed and maintained by recognized standards organizations (in this case, IEEE) and are designed to be publicly accessible and implementable by any vendor, promoting interoperability and compatibility across different devices and network environments. This contrasts with proprietary protocols like CDP (Cisco Discovery Protocol), developed and controlled by a single organization (Cisco, in this case) and may not be as widely adopted or compatible with equipment from other vendors.