Unit 1: Network Infrastructure
This will allow you to demonstrate your networking skills, knowledge, and abilities, with a focus on enterprise-level switching, routing, and multicast components that support cross-platform (inter)operability and integration with the most recent software-defined technologies.
Cisco’s own protocol, called CDP, is used to get information about neighboring devices that are closely connected, such as their hardware, software, names, and more.
CDP versions
- CDPV1: The first version, which could only gather data from devices connected on the other end.
- CDPV2: – The most current version of the protocol, CDPV2, has smarter device tracking capabilities, such as the ability to detect when two devices’ native VLAN IDs on 802.1Q trunks are different or when their duplex states are different.
Working of CDP
Every Cisco device regularly transmits CDP packets; the time interval value is configurable and defaults to 60 seconds. These packets contain an advertisement for a time-to-live (TTL) value in seconds. This value, which is 180 seconds by default, indicates how long the packet must be kept before it can be discarded.
An interface is activated, CDP packets are transmitted with a nonzero time-to-live value. With a zero time-to-live value just before to an interface failure. This helps in quick state discovery.
CDP packets are sent to all Cisco devices, which handle them and store the information in them. A CDP message is never sent on by a Cisco device. If any data changes since the last packet received, the new data is stored and the old data is thrown away, even if its time-to-live value hasn’t run out yet.
Points to note for CDP 
