Qtech QSW-3900-48-Т-AC [175/313] Multicast models

Qtech QSW-3900-RAC [175/313] Multicast models
QTECH Software Configuration Manual
12-174
MSDP, an RP in one domain can establish peering relationships with RPs in other domains. Based on these peering
relationships, RPs in different domains are interconnected and multicast source information is exchanged between the
RPs.
In addition to inter-domain propagation of multicast source information, MSDP has a special application for
PIM-SM: anycast RP. Anycast RP refers to such an application that implements load balancing and redundancy
backup between two or more RPs within a PIM-SM domain by configuring the same IP address for, and establishing
MSDP peering relationships between, these RPs.
12.2.6 Multicast Models
Based on how the receivers treat the multicast sources, there are two multicast models:
ASM model: Any-source multicast model. In the ASM model, any sender can
be a multicast source sending multicast information to a multicast group, and
receivers can join a multicast group identified by a group address and obtain
multicast information addressed to that multicast group. In this model, receivers
are not aware of the location of the multicast source in advance. However, they
can join or leave the multicast group at any time.
SSM model: Source-specific multicast model. In actual situations, users may be
interested in the multicast data only from certain specific multicast sources. The
SSM model provides a transmission service that allows users to specify the
multicast sources they are interested in at the client side.
The multicast routing protocols mentioned in the section above are mainly for the ASM model. In ASM,
receivers cannot specify the multicast sources they are interested in; instead, they passively receive multicast streams
from all multicast sources. Unlike the ASM model, The SSM model allows hosts to specify the multicast sources.
In the SSM model, the multicast address range is different from that in the ASM model and dedicated
multicast forwarding paths between receivers and the specified multicast sources are established through PIM-SM. In
SSM, receivers know exactly where a multicast source is located by means of advertisements, consultancy, and so on.
Therefore, no RP is needed, no RPT is required, there is no source registration process, and there is no need of using
MSDP for discovering sources in other PIM-SM domains. Moreover, routers with receivers on the subnet can learn
the multicast source information specified by the receivers when joining a multicast group in the following two ways:
With IGMPv3 running on the receivers, multicast source addresses are
contained in IGMPv3 report messages.
With IGMPv1 or IGMPv2 running on the receivers, no source addresses are
specified in IGMPv1 or IGMPv2 report messages. In such cases, static SSM
mappings must be configured on the router to map the (*, G) information
carried in these reports to the (G, INCLUDE, (S1, S2…)) information.
12.3 GMRP Overview
GMRP (GARP Multicast Registration Protocol), based on GARP, is used for maintaining multicast registration
information of the switch. All GMRP-capable switches can receive multicast registration information from other
switches, dynamically update local multicast registration information, and send their own local multicast registration
information to other switches. This information switching mechanism keeps consistency of the multicast information
maintained by every GMRP-supporting device in the same switching network.
A host sends a GMRP Join message, if it is interested in joining a multicast group. After receiving the message,

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