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Configuring L2 Multicast Features
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This approach works well for broadcast packets that are intended to be seen or
processed by all connected nodes. In the case of multicast packets, however,
this approach could lead to less efficient use of network bandwidth,
particularly when the packet is intended for only a small number of nodes.
Packets will be flooded into network segments where no node has any interest
in receiving the packet.
What Is IGMP Snooping?
IGMP snooping allows the switch to snoop on IGMP exchanges between
hosts and multicast routers. The IGMP snooping feature complies with RFC
4541. When a switch “sees” an IGMP report from a host for a given multicast
address, the switch adds the host's interface/VLAN to the L2 multicast group
forwarding table and floods the report to all ports in the VLAN. When the
switch sees a leave message for the group, it removes the host interface/VLAN
from the L2 multicast group forwarding table.
IGMP snooping learns about multicast routers by listening for the following
messages:
• IGMP Membership queries
• PIMv1 hellos
• PIMv2 hellos
• DVMRP probes
Group addresses that fall into the range 224.0.0.x are never pruned by IGMP
snooping—they are always flooded to all ports in the VLAN. Note that this
flooding is based on the IP address, not the corresponding 01-00-5e-00-00-xx
MAC address.
When a multicast router is discovered, its interface is added to the interface
distribution list for all multicast groups in the VLAN. If a switch is connected
to a multicast source and no client, the switch filters the traffic from that
group to all interfaces in the VLAN. If the switch sees an IGMP join from a
host in the same VLAN, then it forwards the traffic to the host. Likewise, if
the switch sees a multicast router in the VLAN, it forwards the group to the
multicast router and does not flood in the VLAN. There is a user option to
cause the switch to flood multicast sources in the VLAN if no multicast
clients are present. This option should be enabled when deploying the switch
Summary of Contents for PowerConnect M6220
Page 52: ...52 Introduction ...
Page 86: ...86 Switch Features ...
Page 100: ...100 Hardware Overview ...
Page 116: ...116 Using the Command Line Interface ...
Page 121: ...Default Settings 121 ...
Page 122: ...122 Default Settings ...
Page 142: ...142 Setting Basic Network Information ...
Page 206: ...206 Configuring Authentication Authorization and Accounting ...
Page 292: ...292 Managing General System Settings Figure 11 31 Verify MOTD ...
Page 296: ...296 Managing General System Settings ...
Page 332: ...332 Configuring SNMP ...
Page 408: ...408 Monitoring Switch Traffic ...
Page 560: ...560 Configuring Access Control Lists ...
Page 591: ...Configuring VLANs 591 Figure 21 17 GVRP Port Parameters Table ...
Page 597: ...Configuring VLANs 597 Figure 21 24 Double VLAN Port Parameter Table ...
Page 693: ...Configuring Port Based Traffic Control 693 Figure 24 3 Storm Control 5 Click Apply ...
Page 780: ...780 Configuring Connectivity Fault Management ...
Page 804: ...804 Snooping and Inspecting Traffic Figure 27 17 DAI Interface Configuration Summary ...
Page 818: ...818 Snooping and Inspecting Traffic ...
Page 836: ...836 Configuring Link Aggregation ...
Page 860: ...860 Configuring Data Center Bridging Features ...
Page 906: ...906 Configuring DHCP Server Settings ...
Page 940: ...940 Configuring L2 and L3 Relay Features Figure 34 3 DHCP Relay Interface Summary ...
Page 1080: ...1080 Configuring VRRP ...
Page 1104: ...1104 Configuring IPv6 Routing ...
Page 1131: ...Configuring Differentiated Services 1131 Figure 40 5 DiffServ Class Criteria ...
Page 1158: ...1158 Configuring Class of Service Figure 41 1 Mapping Table Configuration CoS 802 1P ...
Page 1174: ...1174 Configuring Auto VoIP Figure 42 2 Auto VoIP Interface Configuration ...
Page 1240: ...1240 Managing IPv4 and IPv6 Multicast Figure 43 51 DVMRP Next Hop Summary ...
Page 1266: ...1266 Managing IPv4 and IPv6 Multicast ...
Page 1274: ...1274 System Process Definitions ...
Page 1294: ...1294 Index ...