IP Multicast Overview

The JUNOS software implements the following protocols to support IP multicast routing:

• Internet Group Management Protocol (IGMP), Versions 1 and 2--Used to learn whether group members are present.
• Distance Vector Multicast Routing Protocol (DVMRP)--Dense-mode multicast routing protocol.
• Protocol-Independent Multicast (PIM)--Multicast routing protocol that routes to multicast groups that might span wide-area and interdomain internetworks. Both dense mode and sparse mode are supported.
• Multicast Source Discovery Protocol (MSDP)--Multicast routing protocol that discovers active sources of multicast messages. PIM sparse mode uses these sources.
• Session Announcement Protocol (SAP) and Session Description Protocol (SDP)--Handle conference session announcements.

This chapter discusses the following topics that provide background information about IP Multicast:

• IP Multicast Standards
• Multicast Overview
• Multicast Addresses