Juniper ACX2000 Configuration Guide

IGMP is also used as the transport for several related multicast protocols (for example,
Distance Vector Multicast Routing Protocol [DVMRP] and Protocol Independent Multicast
version 1 [PIMv1]).
A routing device receives explicit join and prune messages from those neighboring routing
devices that have downstream group members. When PIM is the multicast protocol in
use, IGMP begins the process as follows:
1. To join a multicast group, G, a host conveys its membership information through IGMP.
2. The routing device then forwards data packets addressed to a multicast group G to
only those interfaces on which explicit join messages have been received.
3. A designated router (DR) sends periodic join and prune messages toward a
group-specific rendezvous point (RP) for each group for which it has active members.
One or more routing devices are automatically or statically designated as the RP, and
all routing devices must explicitly join through the RP.
4. Each routing device along the path toward the RP builds a wildcard (any-source)
state for the group and sends join and prune messages toward the RP.
The term route entry is used to refer to the state maintained in a routing device to
represent the distribution tree.
A route entry can include such fields as:
•
source address
•
group address
•
incoming interface from which packets are accepted
•
list of outgoing interfaces to which packets are sent
•
timers
•
flag bits
The wildcard route entry's incoming interface points toward the RP.
The outgoing interfaces point to the neighboring downstream routing devices that
have sent join and prune messages toward the RP as well as the directly connected
hosts that have requested membership to group G.
5. This state creates a shared, RP-centered, distribution tree that reaches all group
members.
IGMP is also used as the transport for several related multicast protocols (for example,
Distance Vector Multicast Routing Protocol [DVMRP] and Protocol Independent Multicast
version 1 [PIMv1]).
Starting in Junos OS Release 15.2, PIMv1 is not supported.
IGMP is an integral part of IP and must be enabled on all routing devices and hosts that
need to receive IP multicast traffic.
Copyright © 2017, Juniper Networks, Inc.446
ACX Series Universal Access Router Configuration Guide

Juniper ACX2000 Specifications

General

Brand	Juniper
Model	ACX2000
Category	Network Router
Language	English