Siemens RUGGEDCOM ROX II, User Manual

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RUGGEDCOM ROX II
CLI User Guide
Chapter 8
Layer 2
Multicast Filtering Concepts 289
Section 8.4.1
Multicast Filtering Concepts
This section describes some of the concepts important to the implementation of multicast filtering in
RUGGEDCOM ROX II.
CONTENTS
• Section 8.4.1.1, “IGMP”
• Section 8.4.1.2, “GMRP (GARP Multicast Registration Protocol)”
Section 8.4.1.1
IGMP
IGMP is used by IP hosts to report their host group memberships with multicast routers. As hosts join and leave
specific multicast groups, streams of traffic are directed to or withheld from that host.
The IGMP protocol operates between multicast routers and IP hosts. When an unmanaged switch is placed
between multicast routers and their hosts, the multicast streams will be distributed to all ports.This may introduce
significant traffic onto ports that do not require it and receive no benefit from it.
IGMP Snooping, when enabled, will act on IGMP messages sent from the router and the host, restricting traffic
streams to the appropriate LAN segments.
Example: IGMP In Operation
The following network diagram provides a simple example of the use of IGMP.
P1
C3 C4 C1 C2
3
2
3
2
1
4
M2 M1
4 5 4 4
Figure 6: Example – IGMP In Operation
1. Producer 2. Membership Queries 3. Membership Reports 4. Host 5. Mulicast Router