Multicast Address Dynamic Client Allocation Protocol

The Multicast Address Dynamic Client Allocation Protocol (MADCAP) is a communication protocol that allows hosts to request multicast addresses from a server.^[1][2][3]

Overview

The Multicast Address Dynamic Client Allocation Protocol (MADCAP) is designed to allow for automatic dynamic assignment of multicast addresses.^[4]

MADCAP allows for efficient allocation of multicast addresses. This is important for IPv4 which has a small number of multicast addresses available. This is less of a concern with IPv6 multicast. Whereas IPv6 allows for 2¹¹² possible multicast addresses, IPv4 multicast addresses are restricted to only class D Internet addresses (224.0.0.0/4).^[5][6][4]

Port number 2535 is assigned by IANA for use with this protocol.^[7] All protocol messages are encapsulated in UDP datagrams.^[8] The MADCAP protocol has much in common with DHCP, but they are separate protocols with no common dependencies.^[9]

History

MADCAP was originally based on DHCP.^[9] Microsoft included MADCAP as part of the DHCP service in Windows 2000.^[10] RFC 2730 was published as a proposed networking standard by the IETF in December 1999.^[1] Guidelines for the allocation of IPv6 multicast addresses using MADCAP were published in RFC 3307 in August 2002.^[11]