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, for IP version 4 (IPv4) routers.
• Multicast Listener Discovery (MLD), versions 1 and 2—Used to learn whether group members are present, for IP version 6 (IPv6) routers.
• 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:

• IP Multicast Standards
• Multicast Overview
• Multicast Addresses
• Multicast Redundancy
• Replicating Multicast Packets
• Layer 2 Frames and Multicast
• Overview of Multicast Snooping

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