Summary:
Virtual Trunking Protocol (VTP) is used for communication within VLANs. VLANs, short for Virtual LANs, are used in place for traditional LANs for ease of maintenance, and security. The article discusses different VTP protocols.

Body: Communicating within VLANs: There are different protocols available for communicating between VLANs. These encapsulation schemes are also known as VLAN trunking protocols. These protocols are based on Layer 2 of the OSI model.
These are:
1. Inter-Switch Link Protocol (ISL)
2. IEEE 802.10 Protocol
3. IEEE 802.1Q Protocol
4. ATM LANE Protocol