Multicast Overview; Multicast Ip Address Ranges; Notation For Multicast Forwarding States - Juniper J2300 User Manual

Figure 95: Multicast Elements in an IP Network
Multicast
Source
(Group A)
Multicast Multicast
Host
Uninterested Uninterested
Host

Multicast IP Address Ranges

Multicast uses the Class D IP address range (
Multicast addresses usually have a prefix length of
lengths are allowed. Multicast addresses represent logical groupings of
receivers and not physical collections of devices, and can appear only as the
destination in an IP packet, never as the source address.

Notation for Multicast Forwarding States

The multicast forwarding state in a router is usually represented by
one of the following notations:
Multicast
Root
Host
Distribution
Tree(s)
Multicast
router
Prune
Multicast Multicast
router
Multicast
Host Host
Interested
Host
Host
(Group A)
(S,G) notation—S refers to the unicast IP address of the source for the multicast
traffic and G refers to the particular multicast group IP address for which S is
the source. All multicast packets sent from this source have S as the source
address and G as the destination address.
(*, G) notation—The asterisk (*) is a wildcard for the address of any multicast
application source sending to group G. For example, if two sources are
originating exactly the same content for multicast group
can use (*,
224.1.1.2
both sources to the group.
Multicast
Multicast
Source
Host
(Group B)
Multicast
router
Upstream
Join
router
Multicast
Host
Interested
Host
(Group B)
224.0.0.0
) to represent the state of a router forwarding traffic from

Multicast Overview

Downstream
Multicast
router
Join
Multicast Multicast
Host Host
Interested Interested
Host Host
(Group B) (Group B)
through
239.255.255.255
, although other prefix
/32
, a router
224.1.1.2
Multicast Architecture
Leafs
).
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