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Configuring L2 Multicast Features
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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
in scenarios, such as FCoE/FIP snooping, where it is desirable to flood L2
control plane multicast messages that do not utilize well-known multicast
addresses.
By default, multicast routers are aged out every five minutes. The user can
control whether or not multicast routers age out. If all multicast routers age
out, the switch floods the VLAN with the multicast group.
Summary of Contents for PowerConnect 8024
Page 48: ...48 Contents ...
Page 52: ...52 Introduction ...
Page 86: ...86 Switch Features ...
Page 140: ...140 Setting Basic Network Information ...
Page 178: ...178 Managing a Switch Stack ...
Page 204: ...204 Configuring Authentication Authorization and Accounting ...
Page 272: ...272 Managing General System Settings ...
Page 308: ...308 Configuring SNMP ...
Page 336: ...336 Managing Images and Files ...
Page 354: ...354 Auto Image and Configuration Update ...
Page 468: ...468 Configuring Port Characteristics ...
Page 512: ...512 Configuring Port and System Security ...
Page 550: ...550 Configuring Access Control Lists ...
Page 580: ...580 Configuring VLANs Figure 22 17 GVRP Port Parameters Table ...
Page 586: ...586 Configuring VLANs Figure 22 24 Double VLAN Port Parameter Table ...
Page 618: ...618 Configuring VLANs ...
Page 631: ...Configuring the Spanning Tree Protocol 631 Figure 23 5 Spanning Tree Global Settings ...
Page 637: ...Configuring the Spanning Tree Protocol 637 Figure 23 11 RSTP LAG Settings ...
Page 685: ...Configuring Port Based Traffic Control 685 Figure 25 3 Storm Control 5 Click Apply ...
Page 776: ...776 Snooping and Inspecting Traffic Figure 27 17 DAI Interface Configuration Summary ...
Page 790: ...790 Snooping and Inspecting Traffic ...
Page 797: ...Configuring Link Aggregation 797 To view or edit settings for multiple LAGs click Show All ...
Page 894: ...894 Configuring DHCP Server Settings ...
Page 928: ...928 Configuring L2 and L3 Relay Features Figure 34 3 DHCP Relay Interface Summary ...
Page 955: ...Configuring OSPF and OSPFv3 955 Figure 35 1 OSPF Configuration ...
Page 1030: ...1030 Configuring OSPF and OSPFv3 ...
Page 1068: ...1068 Configuring VRRP ...
Page 1092: ...1092 Configuring IPv6 Routing ...
Page 1119: ...Configuring Differentiated Services 1119 Figure 40 5 DiffServ Class Criteria ...
Page 1126: ...1126 Configuring Differentiated Services Figure 40 14 DiffServ Service Summary ...
Page 1142: ...1142 Configuring Differentiated Services ...
Page 1148: ...1148 Configuring Class of Service Figure 41 1 Mapping Table Configuration CoS 802 1P ...
Page 1160: ...1160 Configuring Class of Service ...
Page 1164: ...1164 Configuring Auto VoIP Figure 42 2 Auto VoIP Interface Configuration ...
Page 1230: ...1230 Managing IPv4 and IPv6 Multicast Figure 43 51 DVMRP Next Hop Summary ...
Page 1256: ...1256 Managing IPv4 and IPv6 Multicast ...
Page 1266: ...1266 Feature Limitations and Platform Constants ...
Page 1274: ...1274 System Process Definitions ...
Page 1294: ...Index 1294 ...