C
HAPTER
16
| Multicast Filtering
Layer 2 IGMP (Snooping and Query)
– 425 –
across different subnetworks. Therefore, when PIM routing is enabled for a
subnet on the switch, IGMP is automatically enabled.
Figure 241: IGMP Protocol
L
AYER
2 IGMP
(S
NOOPING
AND
Q
UERY
)
IGMP Snooping and Query – If multicast routing is not supported on other
switches in your network, you can use IGMP Snooping and IGMP Query
(
) to monitor IGMP service requests passing between multicast
clients and servers, and dynamically configure the switch ports which need
to forward multicast traffic. IGMP Snooping conserves bandwidth on
network segments where no node has expressed interest in receiving a
specific multicast service. For switches that do not support multicast
routing, or where multicast routing is already enabled on other switches in
the local network segment, IGMP Snooping is the only service required to
support multicast filtering.
When using IGMPv3 snooping, service requests from IGMP Version 1, 2 or
3 hosts are all forwarded to the upstream router as IGMPv3 reports. The
primary enhancement provided by IGMPv3 snooping is in keeping track of
information about the specific multicast sources which downstream
IGMPv3 hosts have requested or refused. The switch maintains information
about both multicast groups and channels, where a group indicates a
multicast flow for which the hosts have
not
requested a specific source (the
only option for IGMPv1 and v2 hosts unless statically configured on the
switch), and a channel indicates a flow for which the hosts have requested
service from a specific source. For IGMPv1/v2 hosts, the source address of
a channel is always null (indicating that any source is acceptable), but for
IGMPv3 hosts, it may include a specific address when requested.
Only IGMPv3 hosts can request service from a specific multicast source.
When downstream hosts request service from a specific source for a
multicast service, these sources are all placed in the Include list, and traffic
is forwarded to the hosts from each of these sources. IGMPv3 hosts may
also request that service be forwarded from any source except for those
specified. In this case, traffic is filtered from sources in the Exclude list,
and forwarded from all other available sources.
Network core
(multicast routing)
Edge switches
(snooping and query)
Switch to end nodes
(snooping on IGMP clients)
Summary of Contents for DG-GS4826S
Page 2: ...DG GS4826S DG GS4850S E012011 R01 F1 2 2 0 ...
Page 4: ......
Page 6: ...ABOUT THIS GUIDE 6 ...
Page 60: ...SECTION I Getting Started 60 ...
Page 72: ...CHAPTER 1 Introduction System Defaults 72 ...
Page 90: ...CHAPTER 2 Initial Switch Configuration Managing System Files 90 ...
Page 92: ...SECTION II Web Configuration 92 u Unicast Routing on page 539 u Multicast Routing on page 595 ...
Page 138: ...CHAPTER 4 Basic Management Tasks Resetting the System 138 ...
Page 204: ...CHAPTER 6 VLAN Configuration Configuring MAC based VLANs 204 ...
Page 212: ...CHAPTER 7 Address Table Settings Clearing the Dynamic Address Table 212 ...
Page 238: ...CHAPTER 9 Rate Limit Configuration 238 Figure 106 Configuring Rate Limits ...
Page 268: ...CHAPTER 12 Quality of Service Attaching a Policy Map to a Port 268 ...
Page 368: ...CHAPTER 14 Security Measures DHCP Snooping 368 ...
Page 422: ...CHAPTER 15 Basic Administration Protocols Remote Monitoring 422 ...
Page 488: ...CHAPTER 17 IP Configuration Setting the Switch s IP Address IP Version 6 488 ...
Page 538: ...CHAPTER 20 IP Services Forwarding UDP Service Requests 538 ...
Page 594: ...CHAPTER 21 Unicast Routing Configuring the Open Shortest Path First Protocol Version 2 594 ...
Page 624: ...CHAPTER 22 Multicast Routing Configuring PIMv6 for IPv6 624 ...
Page 638: ...CHAPTER 23 Using the Command Line Interface CLI Command Groups 638 ...
Page 712: ...CHAPTER 26 SNMP Commands 712 ...
Page 720: ...CHAPTER 27 Remote Monitoring Commands 720 ...
Page 776: ...CHAPTER 29 Authentication Commands Management IP Filter 776 ...
Page 876: ...CHAPTER 34 Port Mirroring Commands Local Port Mirroring Commands 876 ...
Page 898: ...CHAPTER 37 Address Table Commands 898 ...
Page 998: ...CHAPTER 41 Quality of Service Commands 998 ...
Page 1060: ...CHAPTER 42 Multicast Filtering Commands MLD Proxy Routing 1060 ...
Page 1078: ...CHAPTER 43 LLDP Commands 1078 ...
Page 1088: ...CHAPTER 44 Domain Name Service Commands 1088 ...
Page 1164: ...CHAPTER 47 IP Interface Commands IPv6 to IPv4 Tunnels 1164 ...
Page 1260: ...CHAPTER 48 IP Routing Commands Open Shortest Path First OSPFv3 1260 ...
Page 1304: ...SECTION IV Appendices 1304 ...
Page 1310: ...APPENDIX A Software Specifications Management Information Bases 1310 ...
Page 1343: ...DG GS4826S DG GS4850S E012011 R02 F1 2 2 0 ...
Page 1344: ......