Vyatta Network OS Documentation

Learn how to install, configure and operate the Vyatta NOS, which helps drive our virtual networking & physical platforms portfolio.

Multicast forwarding and PIM

In a multicast network, hosts are responsible for informing routers that they want to receive a particular multicast stream. In IPv4 networks, they do this by using IGMP. In IPv6 networks, they do this by using MLD, which is part of Internet Control Message Protocol for Internet Protocol version 6 (ICMPv6).

Note: For an overview of multicast routing in general, see Ciena Vyatta Network OS Multicast Routing Configuration Guide. For an overview of the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD), see Ciena Vyatta Network OS IGMP and MLD Configuration Guide.

The multicast-capable routers are responsible for replicating messages and forwarding them to the appropriate recipients. To do this replication and forwarding, multicast routers create distribution trees that control the path that IP multicast traffic takes through the network to deliver traffic to all receivers. The vRouter supports the use of Protocol Independent Multicast (PIM) to manage the communication between multicast routers.

Prior to PIM routing protocols, such as DVMRP, included a unicast routing protocol and operated without any dependency on other unicast routing protocols. The independent nature of PIM means that it performs multicast routing independent of a dependency on any specific unicast routing protocol. PIM makes use of whatever unicast routing mechanism (static routing, RIP, OSPF, etc) that is used.