- [Instructor] Cisco introduced,
the Cisco Discovery Protocol, CDP, in 1994,
to provide a mechanism for the management system,
to automatically learn about devices,
connected to the network.
CDP runs on Cisco devices, routers, switches,
phones and so on, and is also licensed,
to run on some network devices from other vendors.
Using CDP network devices periodically advertise,
their own information to a multicast address on the network,
making it available to any device
or application that wishes to listen and collect it.
Over time, enhancements have been made,
to discovery protocols to provide greater capabilities.
Applications such as voice,
have become dependent on these capabilities,
to operate properly,
leading to interoperability problems between vendors,
therefore to allow inter working between vendor equipment,
it has become necessary,
to have a single standardized discovery protocol.
Cisco has been working with other leaders in the internet
and IEEE community,
to develop a new standardized discovery protocol, 802.1AB,
Station and Media Access Control, Connectivity, Discovery
or Link Layer Discovery Protocol, LLDP.
LLDP, which defines basic discovery capabilities,
was enhanced to specifically address the voice application.
This extension to LLDP is called LLDP-MED
or LLDP for Media Endpoint Devices.
As mentioned previously,
a recommended best practice is to disable CDP,
on any ports facing untrusted or unknown networks,
that do not require CDP.
CDP operates at layer two
and can provide attackers with information.
For example, device types, hardware and software versions,
VLAN, and IP address details and so on.
This is information that you would rather not disclose.
The example here, details the configuration steps necessary,
to disable CDP on a global and per interface basis.
In the same way it is recommended to disable CDP,
it is also a best practice to disable LLDP,
in areas of the network that is not needed.
The example also includes,
the configuration steps necessary to disable LLDP,
on a global basis.