16.1.1 General
In the Multicast->General->General Multicast menu you can disable or enable the multic-
ast function.
Fig. 100:
Multicast
->
General
->
General
The Multicast->General->Generalmenu consists of the following fields:
Fields in the Basic Settings menu
Field
Description
Multicast Routing
Select whether Multicast Routing should be used.
The function is enabled with
#/
.
The function is disabled by default.
16.2 IGMP
IGMP (Internet Group Management Protocol, see RFC 3376) is used to signal the informa-
tion about group (membership) in a subnet. As a result, only the packets explicitly wanted
by a host enter the subnet.
Special mechanisms ensure that the requirements of the individual clients are taken into
consideration. At the moment there are three versions of IGMP (V1 - V3); most current sys-
tems use V3, and less often V2.
Two packet types play a central role in IGMP: queries and reports.
Queries are only transmitted from a router. If several IGMP routers exist in a network, the
router with the lowest IP address is the "querier". We differentiate here between a general
query (sent to 224.0.0.1), a group-specific query (sent to a group address) and the group-
and-source-specific query (sent to a specific group address). Reports are only sent by
hosts to respond to queries.
Funkwerk Enterprise Communications GmbH
16 Multicast
bintec Rxxx2/RTxxx2
247
