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C
H A P T E R
20
IGMP
This chapter describes the
IGMP
screens.
20.1 IGMP
Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 sender to 1
recipient) or Broadcast (1 sender to everybody on the network). Multicast delivers IP packets
to just a group of hosts on the network.
IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to establish
membership in a multicast group - it is not used to carry user data. See RFC 1112 and RFC
2236 for information on IGMP versions 1 and 2, respectively.
20.2 IP Multicast Addresses
In IPv4, a multicast address allows a device to send packets to a specific group of hosts
(multicast group) in a different sub-network. A multicast IP address represents a traffic
receiving group, not individual receiving devices. IP addresses in the Class D range (224.0.0.0
to 239.255.255.255) are used for IP multicasting. Certain IP multicast numbers are reserved by
IANA for special purposes (see the IANA web site for more information).
20.2.1 IGMP Snooping
A layer-2 switch can passively snoop on IGMP Query, Report and Leave (IGMP version 2)
packets transferred between IP multicast routers/switches and IP multicast hosts to learn the IP
multicast group membership. It checks IGMP packets passing through it, picks out the group
registration information, and configures multicasting accordingly. IGMP snooping allows the
IES-1248 to learn multicast groups without you having to manually configure them.
The IES-1248 forwards multicast traffic destined for multicast groups (that it has learned from
IGMP snooping or that you have manually configured) to ports that are members of that
group. The IES-1248 discards multicast traffic destined for multicast groups that it does not
know. IGMP snooping generates no additional network traffic, allowing you to significantly
reduce multicast traffic passing through your device.
20.2.2 IGMP Proxy
To allow better network performance, you can use IGMP proxy instead of a multicast routing
protocol in a simple tree network topology.
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Страница 38: ...List of Tables IES 1248 71 73 User s Guide 38 ...
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Страница 51: ...Chapter 2 Hardware Installation IES 1248 71 73 User s Guide 51 Figure 6 IES 1248 Frame Ground Frame Ground ...
Страница 52: ...Chapter 2 Hardware Installation IES 1248 71 73 User s Guide 52 ...
Страница 60: ...Chapter 3 Front Panel Connections IES 1248 71 73 User s Guide 60 ...
Страница 68: ...Chapter 4 MDF Connections IES 1248 71 73 User s Guide 68 ...
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Страница 81: ...Chapter 7 Introducing the Web Configurator IES 1248 71 73 User s Guide 81 Figure 30 Logout ...
Страница 82: ...Chapter 7 Introducing the Web Configurator IES 1248 71 73 User s Guide 82 ...
Страница 110: ...Chapter 12 User Account IES 1248 71 73 User s Guide 110 ...
Страница 116: ...Chapter 13 Switch Setup IES 1248 71 73 User s Guide 116 ...
Страница 118: ...Chapter 14 IP Setup IES 1248 71 73 User s Guide 118 ...
Страница 150: ...Chapter 17 xDSL Profiles Setup IES 1248 71 73 User s Guide 150 ...
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Страница 166: ...Chapter 19 VLAN IES 1248 71 73 User s Guide 166 ...
Страница 184: ...Chapter 22 Multicast VLAN IES 1248 71 73 User s Guide 184 ...
Страница 216: ...Chapter 30 2684 Routed Mode IES 1248 71 73 User s Guide 216 ...
Страница 222: ...Chapter 31 PPPoA to PPPoE IES 1248 71 73 User s Guide 222 ...
Страница 226: ...Chapter 32 DSCP IES 1248 71 73 User s Guide 226 ...
Страница 240: ...Chapter 36 Syslog IES 1248 71 73 User s Guide 240 ...
Страница 248: ...Chapter 37 Access Control IES 1248 71 73 User s Guide 248 ...
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Страница 259: ...Chapter 39 Alarm IES 1248 71 73 User s Guide 259 ...
Страница 260: ...Chapter 39 Alarm IES 1248 71 73 User s Guide 260 ...
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Страница 296: ...Chapter 44 Commands IES 1248 71 73 User s Guide 296 ...
Страница 304: ...Chapter 45 Command Examples IES 1248 71 73 User s Guide 304 ...
Страница 320: ...Chapter 47 DHCP Commands IES 1248 71 73 User s Guide 320 ...
Страница 328: ...Chapter 48 IEEE 802 1Q Tagged VLAN Commands IES 1248 71 73 User s Guide 328 ...
Страница 334: ...Chapter 49 MAC Commands IES 1248 71 73 User s Guide 334 ...
Страница 348: ...Chapter 50 IGMP Commands IES 1248 71 73 User s Guide 348 ...
Страница 352: ...Chapter 51 Packet Filter Commands IES 1248 71 73 User s Guide 352 ...
Страница 362: ...Chapter 53 Firmware and Configuration File Maintenance IES 1248 71 73 User s Guide 362 ...
Страница 394: ...Chapter 55 ADSL Commands IES 1248 71 73 User s Guide 394 ...
Страница 418: ...Chapter 56 Virtual Channel Management IES 1248 71 73 User s Guide 418 ...
Страница 424: ...Chapter 57 ACL Commands IES 1248 71 73 User s Guide 424 ...
Страница 436: ...Chapter 58 Troubleshooting IES 1248 71 73 User s Guide 436 ...
Страница 437: ...437 PART VI Appendices and Index Product Specifications 439 Legal Information 449 Index 457 ...
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Страница 448: ...Appendix B Removing and Installing a Fuse IES 1248 71 73 User s Guide 448 ...
Страница 452: ...Appendix C Legal Information IES 1248 71 73 User s Guide 452 ...
Страница 464: ...Index IES 1248 71 73 User s Guide 464 ...